Facile Synthesis of Gram-Scale Mesoporous Ag/TiO2 Photocatalysts for Pharmaceutical Water Pollutant Removal and Green Hydrogen GenerationClick to copy article linkArticle link copied!
- Yassine CherifYassine CherifLaboratoire de Catalyse et Synthèse en Chimie Organique, Université de Tlemcen, BP 119, Tlemcen13000, AlgeriaMore by Yassine Cherif
- Hajer Azzi*Hajer Azzi*Email: [email protected]Laboratoire de Catalyse et Synthèse en Chimie Organique, Université de Tlemcen, BP 119, Tlemcen13000, AlgeriaInstitut des Sciences et de la Technologie, Université d’Ain Témouchent, BP 284, 46000Ain Témouchent, AlgeriaMore by Hajer Azzi
- Kishore SridharanKishore SridharanDepartment of Nanoscience and Technology, School of Physical Sciences, University of Calicut, P. O. Thenhipalam673635, IndiaMore by Kishore Sridharan
- Seulgi JiSeulgi JiTheoretical Materials & Chemistry Group, Institute of Inorganic Chemistry, University of Cologne, Greinstr. 6, 50939Cologne, GermanyMore by Seulgi Ji
- Heechae ChoiHeechae ChoiTheoretical Materials & Chemistry Group, Institute of Inorganic Chemistry, University of Cologne, Greinstr. 6, 50939Cologne, GermanyMore by Heechae Choi
- Michael G. AllanMichael G. AllanDepartment of Chemistry, Swansea University, Singleton Park, SwanseaSA2 8PP, United KingdomMore by Michael G. Allan
- Sihem BenaissaSihem BenaissaInstitut des Sciences et de la Technologie, Université d’Ain Témouchent, BP 284, 46000Ain Témouchent, AlgeriaMore by Sihem Benaissa
- Karima Saidi-BendahouKarima Saidi-BendahouLaboratoire de Catalyse et Synthèse en Chimie Organique, Université de Tlemcen, BP 119, Tlemcen13000, AlgeriaMore by Karima Saidi-Bendahou
- Lois DampteyLois DampteySchool of Engineering & Innovation, The Open University, Walton Hall, Milton KeynesMK7 6AA, United KingdomMore by Lois Damptey
- Camila Silva RibeiroCamila Silva RibeiroSchool of Engineering & Innovation, The Open University, Walton Hall, Milton KeynesMK7 6AA, United KingdomMore by Camila Silva Ribeiro
- Satheesh KrishnamurthySatheesh KrishnamurthySchool of Engineering & Innovation, The Open University, Walton Hall, Milton KeynesMK7 6AA, United KingdomMore by Satheesh Krishnamurthy
- Sanjay NagarajanSanjay NagarajanDepartment of Chemical Engineering, University of Bath, BathBA2 7AY, United KingdomMore by Sanjay Nagarajan
- M. Mercedes Maroto-ValerM. Mercedes Maroto-ValerResearch Centre for Carbon Solutions, Institute of Mechanical and Processing Engineering, School of Engineering & Physical Science, Heriot-Watt University, EdinburghEH14 4AS, United KingdomMore by M. Mercedes Maroto-Valer
- Moritz F. KuehnelMoritz F. KuehnelDepartment of Chemistry, Swansea University, Singleton Park, SwanseaSA2 8PP, United KingdomFraunhofer Institute for Wind Energy Systems IWES, Am Haupttor 4310, 06237Leuna, GermanyMore by Moritz F. Kuehnel
- Sudhagar Pitchaimuthu*Sudhagar Pitchaimuthu*Email: [email protected]Research Centre for Carbon Solutions, Institute of Mechanical and Processing Engineering, School of Engineering & Physical Science, Heriot-Watt University, EdinburghEH14 4AS, United KingdomMore by Sudhagar Pitchaimuthu
Abstract
This work demonstrates a two-step gram-scale synthesis of presynthesized silver (Ag) nanoparticles impregnated with mesoporous TiO2 and evaluates their feasibility for wastewater treatment and hydrogen gas generation under natural sunlight. Paracetamol was chosen as the model pharmaceutical pollutant for evaluating photocatalytic performance. A systematic material analysis (morphology, chemical environment, optical bandgap energy) of the Ag/TiO2 photocatalyst powder was carried out, and the influence of material properties on the performance is discussed in detail. The experimental results showed that the decoration of anatase TiO2 nanoparticles (size between 80 and 100 nm) with 5 nm Ag nanoparticles (1 wt %) induced visible-light absorption and enhanced charge carrier separation. As a result, 0.01 g/L Ag/TiO2 effectively removed 99% of 0.01 g/L paracetamol in 120 min and exhibited 60% higher photocatalytic removal than pristine TiO2. Alongside paracetamol degradation, Ag/TiO2 led to the generation of 1729 μmol H2 g–1 h–1. This proof-of-concept approach for tandem pollutant degradation and hydrogen generation was further evaluated with rare earth metal (lanthanum)- and nonmetal (nitrogen)-doped TiO2, which also showed a positive response. Using a combination of ab initio calculations and our new theory model, we revealed that the enhanced photocatalytic performance of Ag/TiO2 was due to the surface Fermi-level change of TiO2 and lowered surface reaction energy barrier for water pollutant oxidation. This work opens new opportunities for exploiting tandem photocatalytic routes beyond water splitting and understanding the simultaneous reactions in metal-doped metal oxide photocatalyst systems under natural sunlight.
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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Introduction
Experimental Section
Chemicals
Preparation of Bare and Ag-Doped Mesoporous TiO2
Preparation of N- and La-Doped Mesoporous TiO2
Catalyst Characterization
Photocatalytic Paracetamol Degradation
Photocatalytic H2 Evolution: Sample Preparation
Sample Analysis by Gas Chromatography
Computational Modeling
Results and Discussion
Figure 1
Figure 1. X-ray diffraction analysis of pristine and Ag nanoparticle-coated TiO2 powders.
Figure 2
Figure 2. HRTEM images of the Ag (1 wt %) nanoparticle-coated TiO2 powder at different magnification scales (a) 200 nm, (b) 20 nm, and (c) 2 nm.
Figure 3
Figure 3. XPS core spectra of (a) Ti 2p, (b) O 1s, and (c) Ag 3d. The results of panels (a and b) are compared with those of the commercial P25 powder.
Figure 4
Figure 4. Plots of the Kubelka–Munk function versus the energy of the absorbed light for pure and Ag nanoparticle-coated mesoporous TiO2.
Figure 5
Figure 5. Adsorption–desorption isotherms of nitrogen on pristine and Ag nanoparticle-coated mesoporous TiO2 at 77 K.
Figure 6
Figure 6. (a) UV–Visible absorption spectra of paracetamol photodegradation using 1 wt %Ag/TiO2 and (b) paracetamol photocatalytic degradation over pristine and Ag nanoparticles-coated mesoporous TiO2 under natural solar light irradiation. The results were compared with N- and La-doped TiO2 powder samples. (c) Recycling photocatalytic degradation of paracetamol over 1 wt % Ag/TiO2 under natural solar light irradiation.
Figure 7
Figure 7. Photocatalytic H2 production using different photocatalysts measured at 1 sun irradiation. Note that the electrolyte contains paracetamol (10 ppm) and TEOA, a sacrificial agent.
Figure 8
Figure 8. Gibbs free energy graph as a function of the Fermi level of anatase TiO2 (101) for OER at pH 7 under (a) dark and (b) light irradiation conditions.
Figure 9
Figure 9. Gibbs free energy diagrams of (a) TiO2 and (b) Ag@TiO2 under UV light irradiation.
Figure 10
Figure 10. Schematic illustration of (a) energy band diagrams of pristine anatase TiO2 and Ag@TiO2 and (b) the photocatalytic degradation of paracetamol and hydrogen gas evolution on Ag/TiO2 photocatalysts.
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.2c06657.
Photography of TiO2 and Ag/TiO2 photocatalysts, TEM images, Raman spectra, optical bandgap results, BET results, and UPS results (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Acknowledgments
The authors Y.C. and H.J. would like to thank the Algerian DGRST-MESRS and the University of Tlemcen for financial support. SP thanks Heriot-Watt University for the Seed Grant support. S.J. and H.C. thank the University of Cologne and the Excellence Cluster “Quantum Matter and Materials” for the infrastructural support. S.K. acknowledges the Royal Academy of Engineering Newton Fund and European Commission project id: 958491─Smart innovative system for recycling wastewater and creating closed loops in textile manufacturing industrial processes.
BID | barrier-discharge ionization detector |
CBM | conduction band maximum |
DFT | density functional theory |
GC | gas chromatography |
GGA | generalized gradient approximation |
HRTEM | high-resolution transmission electron microscopy |
JCPDS | joint committee on powder diffraction standards |
LSPR | localized surface plasmon resonance |
OER | oxygen evolution reaction |
Ov | oxygen vacancies |
PAW | projector-augmented wave method |
PBE | Perdew–Burke–Ernzerhof |
PPCP | pharmaceutical and personal care products |
TEOA | triethanolamine |
TOC | total organic carbon |
UPS | ultraviolet photoelectron spectroscopy |
VASP | Vienna ab initio simulation package |
VBM | valence band maximum |
XPS | X-ray photoelectron spectroscopy |
XRD | X-ray diffraction |
References
This article references 91 other publications.
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- 3Jiao, Z.; Zhang, Y.; Ouyang, S.; Yu, H.; Lu, G.; Ye, J.; Bi, Y. BiAg alloy nanospheres: a new photocatalyst for H2 evolution from water splitting. ACS Appl. Mater. Interfaces 2014, 6, 19488– 19493, DOI: 10.1021/am506030pGoogle Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVyhu7nJ&md5=30b5cb58fb5201e709254b8918f6c8f9BiAg Alloy Nanospheres: A New Photocatalyst for H2 Evolution from Water SplittingJiao, Zhengbo; Zhang, Yan; Ouyang, Shuxin; Yu, Hongchao; Lu, Gongxuan; Ye, Jinhua; Bi, YingpuACS Applied Materials & Interfaces (2014), 6 (22), 19488-19493CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)We demonstrate for the first time that Bi and BiAg alloy nanospheres, fabricated with a facile hydrothermal method, display evident photocatalytic H2 prodn. activities. Element Bi can serve as an active photocatalyst for both water splitting and photoelectrochem. applications. More interestingly, these activities of Bi can be greatly enhanced by introducing Ag to form BiAg alloy nanoparticles, which may be ascribed to the improved charge sepn. and enlarged carrier concn. The constituent of the BiAg alloy can be rationally tuned by varying the amt. of Ag nanowires, and it is found that Bi0.7Ag0.3 exhibits the highest photoelectrochem. property.
- 4Chaker, H.; Chérif-Aouali, L.; Khaoulani, S.; Bengueddach, A.; Fourmentin, S. Photocatalytic degradation of methyl orange and real wastewater by silver doped mesoporous TiO2 catalysts. J. Photochem. Photobiol., A 2016, 318, 142– 149, DOI: 10.1016/j.jphotochem.2015.11.025Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFKit7vP&md5=f7e02cdbe42062d84949aa6d202d8a23Photocatalytic degradation of methyl orange and real wastewater by silver doped mesoporous TiO2 catalystsChaker, H.; Cherif-Aouali, L.; Khaoulani, S.; Bengueddach, A.; Fourmentin, S.Journal of Photochemistry and Photobiology, A: Chemistry (2016), 318 (), 142-149CODEN: JPPCEJ; ISSN:1010-6030. (Elsevier B.V.)The photocatalytic activity of silver doped mesoporous TiO2 catalysts was evaluated for water treatment. Doped catalysts were prepd by impregnation-redn with citrate using various Ag loadings (0.5 wt%, 1.5 wt% and 3 wt%) and characterized by X-Ray powder diffraction (XRD), BET and diffuse reflectance UV-vis spectroscopy (DR/UV-vis). Silver doped TiO2 catalysts retain the phys properties of mesoporous TiO2 and its hexagonal order. The degrdn of methyl orange (MO) as a model org pollutant and of a real wastewater effluent was carried out under UVC, UVB, UVA and simulated solar light irradn. Mesoporous TiO2 showed a better activity than P25 TiO2 and photocatalytic performance of silver doped mesoporous TiO2 was enhanced compare to undoped. The mineralization of the org pollutant was investigated by total org carbon (TOC) measurements. The 0.5 wt%Ag/TiO2 exhibited the highest TOC abatement both for the mineralization of MO and of real wastewater under UV and simulated solar light. Moreover, the catalyst was stable and could be used repeatedly. Therefore, this catalyst is promising for photocatalytic wastewater treatment under solar irradn., leading to a cheap technol for developing countries.
- 5Ahmad, K.; Ghatak, H. R.; Ahuja, S. A review on photocatalytic remediation of environmental pollutants and H2 production through water splitting: A sustainable approach. Environ. Technol. Innovation 2020, 19, 100893 DOI: 10.1016/j.eti.2020.100893Google ScholarThere is no corresponding record for this reference.
- 6Zhang, J.; Li, L.; Xiao, Z.; Liu, D.; Wang, S.; Zhang, J.; Hao, Y.; Zhang, W. Hollow sphere TiO2–ZrO2 prepared by self-assembly with polystyrene colloidal template for both photocatalytic degradation and H2 evolution from water splitting. ACS Sustainable Chem. Eng. 2016, 4, 2037– 2046, DOI: 10.1021/acssuschemeng.5b01359Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XivFOms7k%253D&md5=cfe6532d00b14c497b33d43079bd74a3Hollow Sphere TiO2-ZrO2 Prepared by Self-Assembly with Polystyrene Colloidal Template for Both Photocatalytic Degradation and H2 Evolution from Water SplittingZhang, Jianqi; Li, Li; Xiao, Zhixin; Liu, Di; Wang, Shuang; Zhang, Jingjing; Hao, Yuting; Zhang, WenzhiACS Sustainable Chemistry & Engineering (2016), 4 (4), 2037-2046CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)On the basis of a self-assembly technique with polystyrene (PS) spheres as colloidal template, the composite TiO2-ZrO2 hollow spheres are synthesized by combining a water bath with a calcining postprocessing method. XRD, UV-vis/DRS, XPS, SEM-EDS, TEM, HR-TEM, and N2 adsorption-desorption measurements are employed to characterize the compn., structure, and morphol. of TiO2-ZrO2 hollow spheres. The results show that TiO2-ZrO2 hollow spheres are mainly TiO2 anatase and retain well the spherical structure of the PS crystal template, whose shell is closely packed by TiO2-ZrO2 nanoparticles, with thickness of ca. 24 nm. The combination of TiO2 and ZrO2 and the special hollow structure are beneficial to improve the photocatalytic activity. TiO2-ZrO2 hollow spheres have remarkable photocatalytic properties under UV light, simulated sunlight, and microwave-assisted three different modes, which can also degrade org. pollutants of different structures. The H2 evolution quantity in 8 h, which is produced by the photolysis of water, is 23.7 μmol, indicating that TiO2-ZrO2 hollow spheres have a certain hydrogen prodn. performance. The results of the trapping expt. indicate that the active radicals •O2-, h+, and •OH- are responsible for the photocatalytic reaction, and the possible reaction mechanism of TiO2-ZrO2 hollow spheres in both photocatalytic degrdn. and photocatalytic H2 evolution from splitting water is also proposed.
- 7Varma, K. S.; Tayade, R. J.; Shah, K. J.; Joshi, P. A.; Shukla, A. D.; Gandhi, V. G. Photocatalytic degradation of pharmaceutical and pesticide compounds (PPCs) using doped TiO2 nanomaterials: A review. Water-Energy Nexus 2020, 3, 46– 61, DOI: 10.1016/j.wen.2020.03.008Google ScholarThere is no corresponding record for this reference.
- 8Bhatia, V.; Dhir, A. Transition metal doped TiO2 mediated photocatalytic degradation of anti-inflammatory drug under solar irradiations. J. Environ. Chem. Eng. 2016, 4, 1267– 1273, DOI: 10.1016/j.jece.2016.01.032Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitlCntrg%253D&md5=e4089fa10c0a229ca971d78134108ddeTransition metal doped TiO2 mediated photocatalytic degradation of anti-inflammatory drug under solar irradiationsBhatia, Vibhu; Dhir, AmitJournal of Environmental Chemical Engineering (2016), 4 (1), 1267-1273CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)Bismuth (Bi) and Nickel (Ni) Doped Titanium Dioxide (TiO2) nanoparticles were synthesized by sol-gel method and the prepd. nanoparticles were characterized by X-Ray Diffraction, Scanning Electron Microscope, UV-vis reflectance spectroscopy and Brunauer-Emmett-Teller (BET) anal. The concn. of dopant in synthesized catalysts was varied from 0.25 to 1.0 wt%. Maximum BET surface area of 47.8 and 45.7 m2/g was obsd. with 0.25 wt% Bi-TiO2 and 0.5 wt% Ni-TiO2, resp. EDX anal. has established the presence of 0.21% Bi ions and 0.36% Ni ions in 0.25 wt% Bi doped TiO2 and 0.5 wt% Ni doped TiO2, resp. Band gap of Bi-TiO2 (0.25 wt%) and Ni-TiO2 (0.5 wt%) was obtained to be 2.99 eV, which is found to be min. among the various synthesized catalysts. The photocatalytic activity of synthesized catalysts were tested and compared with Degussa TiO2 for degrdn. of Ibuprofen (IBP) as a model compd. Bi-TiO2 nanoparticles revealed higher photocatalytic activity when compared to Ni-TiO2 or Degussa TiO2 under solar irradn., which may be attributed to increase in sp. surface area, and decrease in the crystallite size. Maximum of 89% degrdn. was achieved with 0.25% Bi-TiO2 photocatalyst under 6 h of illuminations with a solar light, whereas, 78% degrdn. has been achieved under similar exptl. condition with Ni doped TiO2. The kinetics of the degrdn. of IBP has been explained in terms of the Langmuir-Hinshelwood model and was found to follow first order kinetics with k value of 0.0064 and 0.0046 min-1 with Bi and Ni doped TiO2, resp.
- 9Mathew, S.; Ganguly, P.; Kumaravel, V.; Bartlett, J.; Pillai, S. C. Solar Light-induced Photocatalytic Degradation of Pharmaceuticals in Wastewater Treatment. In Nano-Materials as Photocatalysts for Degradation of Environmental Pollutants, Singh, P.; Borthakur, A.; Mishra, P. K.; Tiwary, D., Eds.; Elsevier, 2020; Chapter 4, pp 65– 78.Google ScholarThere is no corresponding record for this reference.
- 10Tayade, R. J.; Kulkarni, R. G.; Jasra, R. V. Transition Metal Ion Impregnated Mesoporous TiO2 for Photocatalytic Degradation of Organic Contaminants in Water. Ind. Eng. Chem. Res. 2006, 45, 5231– 5238, DOI: 10.1021/ie051362oGoogle Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsFens70%253D&md5=e9723256e17f812875b6ff0dacc6bce0Transition Metal Ion Impregnated Mesoporous TiO2 for Photocatalytic Degradation of Organic Contaminants in WaterTayade, Rajesh J.; Kulkarni, Ramchandra G.; Jasra, Raksh. V.Industrial & Engineering Chemistry Research (2006), 45 (15), 5231-5238CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Mesoporous nanocryst. TiO2 was prepd. by hydrolysis of titanium isopropoxide, and the band gap of the TiO2 was modified with the transition metal ions Ag, Co, Cu, Fe, and Ni, having different work functions, by the wet impregnation method. X-ray diffraction (XRD), x-ray photoelectron spectrophotometry, diffuse reflectance spectrophotometry (DRS), SEM, and BET techniques were used for the characterization of the catalysts. By using the DRS technique, the highest red shift of 11 nm and lowest of 1.5 nm were obsd. for Ni- and Fe ion-impregnated catalysts, resp. The investigations were carried out to demonstrate the effect of ionic radius and work function of metal ions on photocatalytic activity of mesoporous nanocryst. TiO2 for degrdn. of acetophenone and nitrobenzene in aq. medium under UV light irradn.
- 11Xiong, Z.; Ma, J.; Ng, W. J.; Waite, T. D.; Zhao, X. S. Silver-modified mesoporous TiO2 photocatalyst for water purification. Water Res. 2011, 45, 2095– 2103, DOI: 10.1016/j.watres.2010.12.019Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXitFaqurg%253D&md5=1337639a5250674d4251a2cb8f8d7b9eSilver-modified mesoporous TiO2 photocatalyst for water purificationXiong, Zhigang; Ma, Jizhen; Ng, Wun Jern; Waite, T. David; Zhao, X. S.Water Research (2011), 45 (5), 2095-2103CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)Mesoporous anatase (TiO2) was modified with silver (Ag) nanoparticles using a photoredn. method. Performance of the resulting TiO2-Ag nanocomposites for water purifn. was evaluated using degrdn. of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli) under UV irradn. The composites with different Ag loadings were characterized using phys. adsorption of nitrogen, X-ray diffraction, XPS and UV-Visible diffuse reflectance spectroscopic techniques. The results showed that metallic Ag nanoparticles were firmly immobilized on the TiO2 surface, which improved electron-hole sepn. by forming the Schottky barrier at the TiO2-Ag interface. Photocatalytic degrdn. of RhB and inactivation of E. coli effectively occurred in an analogical trend. The deposited Ag slightly decreased adsorption of target pollutants, but greatly increased adsorption of mol. oxygen with the latter enhancing prodn. of reactive oxygen species (ROSs) with concomitant increase in contaminant photodegrdn. The optimal Ag loadings for RhB degrdn. and E. coli disinfection were 0.25 wt% and 2.0 wt%, resp. The composite photocatalysts were stable and could be used repeatedly under UV irradn.
- 12Lin, C. J.; Yang, W.-T.; Chou, C.-Y.; Liou, S. Y. H. Hollow mesoporous TiO2 microspheres for enhanced photocatalytic degradation of acetaminophen in water. Chemosphere 2016, 152, 490– 495, DOI: 10.1016/j.chemosphere.2016.03.017Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XkslKhsbo%253D&md5=cd22c50ed44b097189adf5f701a70ef4Hollow mesoporous TiO2 microspheres for enhanced photocatalytic degradation of acetaminophen in waterLin, Chin Jung; Yang, Wen-Ta; Chou, Chen-Yi; Liou, Sofia Ya HsuanChemosphere (2016), 152 (), 490-495CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)Hollow core-shell mesoporous TiO2 microspheres were synthesized by a template-free solvothermal route for efficient photocatalytic degrdn. of acetaminophen. X-ray diffraction, SEM, transmission electron microscopy, and Barrett-Joyner-Halenda data revealed a micrometer-sized mesoporous anatase TiO2 hollow sphere with large surface area and efficient light harvesting. For the photocatalytic degrdn. of acetaminophen in 60 min, the conversion fraction of the drug increased from 88% over com. Degussa P25 TiO2 to 94% over hollow spheres with about 25% increase in the initial reaction rate. Even after 10 repeated runs, the recycled hollow spheres showed good photodegrdn. activity. The intermediates generated in the photocatalytic reactions were eventually converted into mols. that are easier to handle. The simple fabrication route would facilitate the development of photocatalysts for the decompn. of environmental contaminants.
- 13Alvarez-Corena, J. R.; Bergendahl, J. A.; Hart, F. L. Advanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identification. J. Environ. Manage. 2016, 181, 544– 551, DOI: 10.1016/j.jenvman.2016.07.015Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1ShsbzN&md5=fcda1324df71478d953b5cd395f5408aAdvanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identificationAlvarez-Corena, Jose R.; Bergendahl, John A.; Hart, Fred L.Journal of Environmental Management (2016), 181 (), 544-551CODEN: JEVMAW; ISSN:0301-4797. (Elsevier Ltd.)The extent and kinetics of degrdn. of 1,4 dioxane, n-nitrosodimethylamine (NDMA), tris-2-chloroethyl phosphate (TCEP), gemfibrozil, and 17β estradiol in a prepd. aq. matrix by means of UV/TiO2 (UV light/titanium dioxide) oxidn. was evaluated. Degussa P25 TiO2 was employed as a photocatalyst excited by UV light in a 1 L water-jacketed batch photoreactor. The rate of degrdn. was modeled using a pseudo-first order rate model and the Langmuir-Hinshelwood rate model with a high correlation. Degrdn. rate consts. were found to be max. at pH 5.0 and 1.5 g L-1 TiO2 dose. For these conditions first order rate consts., values were as follows: 0.29 min-1 for 1,4 dioxane, 0.50 min-1 for NDMA, 0.12 min-1 for TCEP, 0.61 min-1 for gemfibrozil, and 0.53 min-1 for 17β estradiol. While for the Langmuir-Hinshelwood rate model, the following consts. were found: 0.11 Lmg-1 and 2.81 mgL-1 min-1 for 1,4 dioxane, 0.12 Lmg-1 and 4.35 mgL-1 min-1 for NDMA, 0.06 Lmg-1 and 1.79 mgL-1 min-1 for TCEP, 0.21 Lmg-1 and 3.27 mgL-1 min-1 for gemfibrozil, and 0.15 Lmg-1 and 3.43 mgL-1 min-1 for 17β estradiol. In addn., specific byproducts of degrdn. were identified using GC/MS anal. The results obtained from the kinetics anal. showed that UV/TiO2 oxidn. is a promising process for treating trace org. contaminants in water, but further research is needed to better understand how to incorporate these findings into pilot and full-scale designs. The toxicity of oxidn. byproducts, and their potential for interacting with other compds. should be considered in the treatment of contaminated waters using the UV/TiO2 oxidn. process.
- 14Jin-hui, Z. Research on UV/TiO2 Photocatalytic Oxidation of Organic Matter in Drinking Water and Its Influencing Factors. Procedia Environ. Sci. 2012, 12, 445– 452, DOI: 10.1016/j.proenv.2012.01.302Google ScholarThere is no corresponding record for this reference.
- 15Wu, Q.; Zhao, J.; Qin, G.; Wang, C.; Tong, X.; Xue, S. Photocatalytic reduction of Cr(VI) with TiO2 film under visible light. Appl. Catal., B 2013, 142–143, 142– 148, DOI: 10.1016/j.apcatb.2013.04.056Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1eks7nI&md5=22e1357544670e2f773cf21679246dd3Photocatalytic reduction of Cr(VI) with TiO2 film under visible lightWu, Quanping; Zhao, Jun; Qin, Guohui; Wang, Chengyang; Tong, Xinli; Xue, SongApplied Catalysis, B: Environmental (2013), 142-143 (), 142-148CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)The performance of photocatalytic redn. of chromium (VI) via a new TiO2 film and a platinum anode was systematically evaluated. The as-prepd. TiO2 film is composed of a dye-sensitized zone and a catalysis zone. Charge sepn. was accomplished with electron transferring to the catalysis zone and pos. charge transforming to an anode. A powerful redn. ability of the reaction system was achieved in the absence of any orgs. under visible light irradn. Several parameters including pH, dissolved O2, the primary active species, the durability of the as-synthesized film and so on were investigated.
- 16Sudhagar, P.; Devadoss, A.; Nakata, K.; Terashima, C.; Fujishima, A. Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2 Nanostructures through Amplifying Light Reception and Surface States Passivation. J. Electrochem. Soc. 2015, 162, H108– H114, DOI: 10.1149/2.0161503jesGoogle Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFClsrk%253D&md5=9226e2c49b92226a6a725f7e8081fb85Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2 Nanostructures through Amplifying Light Reception and Surface States PassivationSudhagar, P.; Devadoss, Anitha; Nakata, K.; Terashima, C.; Fujishima, A.Journal of the Electrochemical Society (2015), 162 (3), H108-H114CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)The effect of rare earth gadolinium (Gd3+) ion doping on optical and photoelectrochem. properties of TiO2 is studied. The hierarchical clump-type TiO2 nanostructure was fabricated using polyvinyl acetate as soft-template. The optical absorbance quantity of TiO2 was strikingly promoted at bandgap energy region (380 nm) by Gd3+ doping, as well as it extend a wide absorbance in visible wavelength region (400-800 nm) elucidating the sub-bandgap formation. As a result, Gd3+:TiO2 exhibits high photocurrent d. than undoped TiO2 in photoelectrocatalytic expts. Another plausible reason for enhancing the photocurrent d. at Gd3+:TiO2 was analyzed through electrochem. impedance spectroscopy. The underlying mechanism of surface states controlled charge transfer at TiO2/electrolyte interfaces affected the photoelectrocatalytic hydrogen fuel generation, and compete with Gd3+ ion doping through bottlenecking of photoelectrons trapping at surface states. The improved charge sepn. (e-/h+) at Gd3+:TiO2 result effective photoelectron collection and thus yield 180 % higher hydrogen gas (∼ 2.34 mL.h-1.cm-2 ) generation compare to pristine TiO2 (1.28 mL.h-1.cm-2) under UV light irradn. The improved optical and charge transfer characteristics of hierarchical TiO2 by Gd3+ ions can be implemented to wide range of other metal oxide based photocatalytic fuel generation.
- 17Naldoni, A.; Altomare, M.; Zoppellaro, G.; Liu, N.; Kment, Š.; Zbořil, R.; Schmuki, P. Photocatalysis with Reduced TiO2: From Black TiO2 to Cocatalyst-Free Hydrogen Production. ACS Catal. 2019, 9, 345– 364, DOI: 10.1021/acscatal.8b04068Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitlylsLzL&md5=a70417c49844b431e2055bbaa2874c37Photocatalysis with Reduced TiO2: From Black TiO2 to Cocatalyst-Free Hydrogen ProductionNaldoni, Alberto; Altomare, Marco; Zoppellaro, Giorgio; Liu, Ning; Kment, Stepan; Zboril, Radek; Schmuki, PatrikACS Catalysis (2019), 9 (1), 345-364CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. Black TiO2 nanomaterials have recently emerged as promising candidates for solar-driven photocatalytic hydrogen prodn. Despite the great efforts to synthesize highly reduced TiO2, it is apparent that intermediate degree of redn. (namely, gray titania) brings about the formation of peculiar defective catalytic sites enabling cocatalyst-free hydrogen generation. A precise understanding of the structural and electronic nature of these catalytically active sites is still elusive, as well as the fundamental structure-activity relationships that govern formation of crystal defects, increased light absorption, charge sepn., and photocatalytic activity. In this Review, we discuss the basic concepts that underlie an effective design of reduced TiO2 photocatalysts for hydrogen prodn. such as (i) defects formation in reduced TiO2, (ii) anal. of structure deformation and presence of unpaired electrons through ESR spectroscopy, (iii) insights from surface science on electronic singularities due to defects, and (iv) the key differences between black and gray titania, i.e., photocatalysts that require Pt-modification and cocatalyst-free photocatalytic hydrogen generation. Finally, future directions to improve the performance of reduced TiO2 photocatalysts are outlined.
- 18Do, H. H.; Nguyen, D. L. T.; Nguyen, X. C.; Le, T.-H.; Nguyen, T. P.; Trinh, Q. T.; Ahn, S. H.; Vo, D.-V. N.; Kim, S. Y.; Le, Q. V. Recent progress in TiO2-based photocatalysts for hydrogen evolution reaction: A review. Arabian J. Chem. 2020, 13, 3653– 3671, DOI: 10.1016/j.arabjc.2019.12.012Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXnvVKktQ%253D%253D&md5=563ba32f3b82b214b734932f228c552dRecent progress in TiO2-based photocatalysts for hydrogen evolution reaction: A reviewDo, Ha Huu; Nguyen, Dang Le Tri; Nguyen, Xuan Cuong; Le, Thu-Ha; Nguyen, Thang Phan; Trinh, Quang Thang; Ahn, Sang Hyun; Vo, Dai-Viet N.; Kim, Soo Young; Le, Quyet VanArabian Journal of Chemistry (2020), 13 (2), 3653-3671CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)A review. TiO2 has gained tremendous attention as a cutting-edge material for application in photocatalysis. The performance of TiO2 as a photocatalyst depends on various parameters including morphol., surface area, and crystallinity. Although TiO2 has shown good catalytic activity in various catalysis systems, the performance of TiO2 as a photocatalyst is generally limited due to its low cond. and a wide optical bandgap. Numerous different studies have been devoted to overcome these problems, showing significant improvement in photocatalytic performance. In this study, we summarize the recent progress in the utilization of TiO2 for the photocatalytic hydrogen evolution reaction (HER). Strategies for modulating the properties toward the high photocatalytic activity of TiO2 for HER including structural engineering, compositional engineering, and doping are highlighted and discussed. The advantages and limitations of each modification approach are reviewed. Finally, the remaining obstacles and perspective for the development of TiO2 as photocatalysts toward high efficient HER in the near future are also provided.
- 19Yang, S.; Tang, W.; Ishikawa, Y.; Feng, Q. Synthesis of titanium dioxide with oxygen vacancy and its visible-light sensitive photocatalytic activity. Mater. Res. Bull. 2011, 46, 531– 537, DOI: 10.1016/j.materresbull.2011.01.004Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXisFeis70%253D&md5=17c7e1b4610591a54f9f90921c13407eSynthesis of titanium dioxide with oxygen vacancy and its visible-light sensitive photocatalytic activityYang, Si-Tao; Tang, Wei-Ping; Ishikawa, Yoshie; Feng, QiMaterials Research Bulletin (2011), 46 (4), 531-537CODEN: MRBUAC; ISSN:0025-5408. (Elsevier Ltd.)A novel active carbon reducing process was developed for the synthesis of titania with oxygen vacancy. In this process a nanocomposite of hydrolyzed titanium(IV) tetra-isopropoxide and the active carbon was annealed in air. The formation reaction, visible-light absorption, and visible-light sensitive photocatalytic activity of the titania with oxygen vacancy samples were investigated using XRD, TG-DTA analyses, FE-SEM, EDS, and measurements of elec. cond., BET sp. surface area and photocatalytic activity. The nonstoichiometric titania with oxygen vacancy sample has a rutile structure and its chem. formula can be written as Ti(IV)1-xTi(III)xO(2-x/2).box.x/2, where .box. is oxygen vacancy. The oxygen vacancy was introduced into the rutile structure by reducing reaction of the active carbon in a phase transformation process from anatase to rutile. The samples showed visible-light absorption with an absorption edge around 570 nm and high surface visible-light sensitive photocatalytic activity.
- 20Hirakawa, H.; Hashimoto, M.; Shiraishi, Y.; Hirai, T. Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface Oxygen Vacancies of Titanium Dioxide. J. Am. Chem. Soc. 2017, 139, 10929– 10936, DOI: 10.1021/jacs.7b06634Google Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFOmtrbL&md5=241bee5e6568ff455e289e7f23d6e585Photocatalytic conversion of nitrogen to ammonia with water on surface oxygen vacancies of titanium dioxideHirakawa, Hiroaki; Hashimoto, Masaki; Shiraishi, Yasuhiro; Hirai, TakayukiJournal of the American Chemical Society (2017), 139 (31), 10929-10936CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Ammonia (NH3) is an essential chem. in modern society. It is currently manufd. by the Haber-Bosch process using H2 and N2 under extremely high-pressure (>200 bar) and high-temp. (>673 K) conditions. Photocatalytic NH3 prodn. from water and N2 at atm. pressure and room temp. is ideal. Several semiconductor photocatalysts have been proposed, but all suffer from low efficiency. Here we report that a com. available TiO2 with a large no. of surface oxygen vacancies, when photoirradiated by UV light in pure water with N2, successfully produces NH3. The active sites for N2 redn. are the Ti3+ species on the oxygen vacancies. These species act as adsorption sites for N2 and trapping sites for the photoformed conduction band electrons. These properties therefore promote efficient redn. of N2 to NH3. The solar-to-chem. energy conversion efficiency is 0.02%, which is the highest efficiency among the early reported photocatalytic systems. This noble-metal-free TiO2 system therefore shows a potential as a new artificial photosynthesis for green NH3 prodn.
- 21Hao, Y.-n.; Chen, T.; Zhang, X.; Zhou, H.; Ma, Y. Ti-Ti σ bond at oxygen vacancy inducing the deep defect level in anatase TiO2 (101) surface. J. Chem. Phys. 2019, 150, 224702 DOI: 10.1063/1.5108595Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtFOktrrN&md5=f3c6106ad675a4a4ec21d28ac7864a5aTi-Ti σ bond at oxygen vacancy inducing the deep defect level in anatase TiO2 (101) surfaceHao, Ya-nan; Chen, Tingwei; Zhang, Xiao; Zhou, He; Ma, YuchenJournal of Chemical Physics (2019), 150 (22), 224702/1-224702/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the deep defect state in this surface obsd. exptl., which is 1 eV below the Fermi level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the d. functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi level of anatase near the conduction band bottom. Our GW calcns. can explain satisfactorily the coexistence of shallow and deep defect states in anatase as obsd. in expts. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calcd. bandgap of the reduced anatase agree well with the expts. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U. (c) 2019 American Institute of Physics.
- 22Wang, Y.; Zhang, M.; Lv, S.; Li, X.; Wang, D.; Song, C. Photogenerated Oxygen Vacancies in Hierarchical Ag/TiO2 Nanoflowers for Enhanced Photocatalytic Reactions. ACS Omega 2020, 5, 13994– 14005, DOI: 10.1021/acsomega.0c01390Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVGhurfL&md5=6344654ba9d168684220f8e359272c76Photogenerated Oxygen Vacancies in Hierarchical Ag/TiO2 Nanoflowers for Enhanced Photocatalytic ReactionsWang, Ying; Zhang, Miaomiao; Lv, Shuhua; Li, Xiaoqian; Wang, Debao; Song, CaixiaACS Omega (2020), 5 (23), 13994-14005CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)Oxygen vacancy (Vo) creation and morphol. controlling make significant contributions to the electronic and structural regulation of metal oxide semiconductors, yet an investigation about convenient approaches for fabricating hierarchical catalyst with abundant oxygen vacancies still has significant challenges. Here, we report a unique method to create abundant oxygen vacancies in hierarchical Ag/TiO2 nanoflowers during photocatalytic reaction, which is accompanied by light absorption variation and surface plasmon resonance (SPR) enhancement. Its high efficiency of photocatalytic H2 evolution (the highest apparent quantum yield reaches 3.2% at 365 nm) and rhodamine B degrdn. can be considered as benefits from the synergistic effects of the well-arranged hierarchical structure, the photogenerated oxygen vacancies, and the SPR of cocatalyst Ag. This work proposes an effective strategy to optimize the synthesis of regular hierarchical structures and enriches the research on the vital function of oxygen vacancies in photocatalytic reactions.
- 23Bi, X.; Du, G.; Kalam, A.; Sun, D.; Yu, Y.; Su, Q.; Xu, B.; Al-Sehemi, A. G. Tuning oxygen vacancy content in TiO2 nanoparticles to enhance the photocatalytic performance. Chem. Eng. Sci. 2021, 234, 116440 DOI: 10.1016/j.ces.2021.116440Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvF2rtb0%253D&md5=2e7c550c82189a682dba4c9c342a23d3Tuning oxygen vacancy content in TiO2 nanoparticles to enhance the photocatalytic performanceBi, Xiang; Du, Gaohui; Kalam, Abul; Sun, Dongfeng; Yu, Yuan; Su, Qingmei; Xu, Bingshe; Al-Sehemi, Abdullah G.Chemical Engineering Science (2021), 234 (), 116440CODEN: CESCAC; ISSN:0009-2509. (Elsevier Ltd.)White TiO2 (W-TiO2), gray TiO2 (G-TiO2) and black TiO2 (B-TiO2) have been prepd. through simple annealing process in different atmospheres. The oxygen vacancy content in the TiO2 samples and the relationship between oxygen vacancy and photocatalytic performance have been studied by comprehensive analyses. The XRD peaks slightly move to a low angle and the Raman strongest peak shifts pos. owing to oxygen vacancy and Ti3+. The energy bandgap of G-TiO2 and B-TiO2 is tuned from 3.10 to 3.02 and 1.99 eV. The content of oxygen vacancy is 1%, 4.8% and 7.8% for W-TiO2, G-TiO2 and B-TiO2, resp. The efficiency of NO removal is stable at 34%, 38% and 45%, and the decompn. rate of Rhodamine B under visible light is 75%, 83% and 89% for W-TiO2, G-TiO2 and B-TiO2, resp. The results are significant for the design of high-performance photocatalytic materials in the field of solar energy conversion.
- 24Pedroza-Herrera, G.; Medina-Ramírez, I. E.; Lozano-Álvarez, J. A.; Rodil, S. E. Evaluation of the Photocatalytic Activity of Copper Doped TiO2 nanoparticles for the Purification and/or Disinfection of Industrial Effluents. Catal. Today 2020, 341, 37– 48, DOI: 10.1016/j.cattod.2018.09.017Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXis1WhsLvF&md5=4733d301098017b7bb742a5c4c1180d0Evaluation of the Photocatalytic Activity of Copper Doped TiO2 nanoparticles for the Purification and/or Disinfection of Industrial EffluentsPedroza-Herrera, Gladis; Medina-Ramirez, Iliana E.; Lozano-Alvarez, Juan Antonio; Rodil, Sandra E.Catalysis Today (2020), 341 (), 37-48CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)In this article, visible light active, copper doped TiO2 nanoparticles are discussed as potential candidates for the tertiary treatment of industrial effluents. Our aim was to develop sustainable photocatalytic materials that exhibit excellent activity and biocompatibility. The photocatalysts were prepd. using a two-step procedure: sol-gel synthesis followed by microwave hydrothermal treatment. Copper (Cu) was chosen as doping agent because it has been previously reported that Cu is a good doping element that improves the photocatalytic performance of TiO2. The incorporation of Cu into the TiO2 matrix was demonstrated by X ray photoelectron spectroscopy and a bandgap redn. down to 2.86 eV was achieved at relatively low doping levels (nominal 2.0%). A moderate photocatalytic activity was obsd. for the degrdn. of diclofenac and for the removal of dissolved org. matter contained in an industrial effluent. The removal efficiency of the nanoparticles increased linearly with the amt. of copper doping. For instance after 7 h of illumination, diclofenac degrdn. efficiencies of 21.41, 28.95 and 33.26% were obsd. for TiO2-Cu (1.0, 1.5 and 2.0%) resp. Meanwhile, disinfection of the effluents was attained within five hours of treatment under visible light, in our irradn. conditions. Hydrogen peroxide improved the photocatalytic activity of the nanoparticles since the release of Cu2+ ions give rise to a combined degrdn. mechanism: photocatalysis + photo-Fenton. The lixiviation of Cu2+ ions was demonstrated by at. absorption spectroscopy. Moreover, The Cu doped TiO2 nanostructures exhibited excellent antibacterial properties against both gram neg. and pos. bacteria and do not exert any cytotoxicity to human blood cells. The biocompatibility of the Cu doped TiO2 nanoparticles combined with their photocatalytic activity under room light illumination suits them as excellent candidates for the development of sustainable environmental remediation technologies.
- 25Armaković, S. J.; Grujić-Brojčin, M.; Šćepanović, M.; Armaković, S.; Golubović, A.; Babić, B.; Abramović, B. F. Efficiency of La-doped TiO2 calcined at different temperatures in photocatalytic degradation of β-blockers. Arabian J. Chem. 2019, 12, 5355– 5369, DOI: 10.1016/j.arabjc.2017.01.001Google Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1Witb4%253D&md5=a883a27ce202ab6998ad4232a3fb8bb8Efficiency of La-doped TiO2 calcined at different temperatures in photocatalytic degradation of β-blockersArmakovic, Sanja J.; Grujic-Brojcin, Mirjana; Scepanovic, Maja; Armakovic, Stevan; Golubovic, Aleksandar; Babic, Biljana; Abramovic, Biljana F.Arabian Journal of Chemistry (2019), 12 (8), 5355-5369CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)Photocatalytic activity of titania-based photocatalysts doped with 1% La has been tested in UVA radiation-induced degrdn. of two β-blockers - metoprolol tartrate (MET) and propranolol hydrochloride (PRO). Photocatalysts have been synthesized by sol-gel process followed by calcination at various temps. in the range of 450-750°C. The great impact of calcination temp. on the structural, compositional and morphol. properties of prepd. catalysts has been revealed by XRPD, SEM, BET and Raman scattering measurements. Doped catalysts calcined at 450-650°C, with dominant anatase phase and developed mesoporous structure, have displayed higher photocatalytic performance than much less porous samples calcined at 700-750°C, with sodium hexatitanate as dominant phase. Also, La-doped anatase sample has shown higher efficiency in degrdn. of MET and PRO in comparison with the efficiency of undoped TiO2 nanopowders calcined at same temps. The quenching effects of various scavengers suggest that the major role in degrdn. of MET may be attributed to reactive radicals, whereas photogenerated holes are mainly responsible for degrdn. of PRO. Applying d. functional theory (DFT) calcns., we analyzed fundamental structural and electronic properties (total and polar surface areas, frontier MOs, optoelectronic properties and av. local ionization energy surfaces) of MET and PRO mols., which are of significance for the understanding of more effective degrdn. of PRO in comparison with MET.
- 26Zhu, X.; Pei, L.; Zhu, R.; Jiao, Y.; Tang, R.; Feng, W. Preparation and characterization of Sn/La co-doped TiO2 nanomaterials and their phase transformation and photocatalytic activity. Sci. Rep. 2018, 8, 12387 DOI: 10.1038/s41598-018-30050-3Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3c7ptlGitQ%253D%253D&md5=4257f8f3cd53222dad4e7dfa4904752aPreparation and characterization of Sn/La co-doped TiO2 nanomaterials and their phase transformation and photocatalytic activityZhu Xiaodong; Pei Lingxiu; Zhu Ranran; Feng Wei; Zhu Xiaodong; Jiao Yu; Zhu Xiaodong; Feng Wei; Jiao Yu; Tang RenyongScientific reports (2018), 8 (1), 12387 ISSN:.The pure, tin (Sn)-doped, lanthanum (La)-doped and Sn/La co-doped titanium dioxide (TiO2) nanomaterials were synthesized using sol-gel method followed by calcination at the temperature of 360 °C, 450 °C and 600 °C, respectively. The structures of the nanomaterials were characterized by X-ray diffraction (XRD), Thermogravimetric (TG), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrum (EDS), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectrum (XPS), Diffuse Reflectance Spectrum (DRS), Photoluminescence Spectrum (PL), Brunauer-Emmett-Teller Measurements (BET), respectively. The photocatalytic property of the photocatalysts under UV light was evaluated through the degradation of Rhodamine B (RhB). The results show that the anatase-rutile phase transition is promoted by Sn-doping while La-doping retards the phase transition. However, La doping plays a major role in the process of phase transformation. The photocatalytic activity of pure TiO2 is affected by annealing temperature remarkably and the optimal annealing temperature is 450 °C. The photocatalytic activity of TiO2 is enhanced significantly by Sn and La doping at three different temperatures. Sn/La-TiO2 exhibits the highest degradation rates and the fastest reaction rates probably owing to the synergistic effect of Sn(4+) and La(3+) ions in inhibiting the recombination of photogenerated electron-hole pairs. The formation of extra surface hydroxyl groups and additional surface area are also beneficial for the photocatalytic activity.
- 27Kumar, A.; Choudhary, P.; Kumar, A.; Camargo, P. H. C.; Krishnan, V. Recent Advances in Plasmonic Photocatalysis Based on TiO2 and Noble Metal Nanoparticles for Energy Conversion, Environmental Remediation, and Organic Synthesis. Small 2022, 18, 2101638 DOI: 10.1002/smll.202101638Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsl2ku7vO&md5=ee5ff8b3e43f24b24b8799923e01f898Recent advances in plasmonic photocatalysis based on TiO2 and noble metal nanoparticles for energy conversion, environmental remediation, and organic synthesisKumar, Ajay; Choudhary, Priyanka; Kumar, Ashish; Camargo, Pedro H. C.; Krishnan, VenkataSmall (2022), 18 (1), 2101638CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Plasmonic photocatalysis has emerged as a prominent and growing field. It enables the efficient use of sunlight as an abundant and renewable energy source to drive a myriad of chem. reactions. For instance, plasmonic photocatalysis in materials comprising TiO2 and plasmonic nanoparticles (NPs) enables effective charge carrier sepn. and the tuning of optical response to longer wavelength regions (visible and near IR). In fact, TiO2-based materials and plasmonic effects are at the forefront of heterogeneous photocatalysis, having applications in energy conversion, prodn. of liq. fuels, wastewater treatment, nitrogen fixation, and org. synthesis. This review aims to comprehensively summarize the fundamentals and to provide the guidelines for future work in the field of TiO2-based plasmonic photocatalysis comprising the above-mentioned applications. The concepts and state-of-the-art description of important parameters including the formation of Schottky junctions, hot electron generation and transfer, near field electromagnetic enhancement, plasmon resonance energy transfer, scattering, and photothermal heating effects have been covered in this review. Synthetic approaches and the effect of various physicochem. parameters in plasmon-mediated TiO2-based materials on performances are discussed. It is envisioned that this review may inspire and provide insights into the rational development of the next generation of TiO2-based plasmonic photocatalysts with target performances and enhanced selectivities.
- 28Kumar, A.; Choudhary, P.; Krishnan, V. Selective and efficient aerobic oxidation of benzyl alcohols using plasmonic Au-TiO2: Influence of phase transformation on photocatalytic activity. Appl. Surf. Sci. 2022, 578, 151953 DOI: 10.1016/j.apsusc.2021.151953Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1KisbjO&md5=79444127df3002d4db5b175e710f0568Selective and efficient aerobic oxidation of benzyl alcohols using plasmonic Au-TiO2: Influence of phase transformation on photocatalytic activityKumar, Ajay; Choudhary, Priyanka; Krishnan, VenkataApplied Surface Science (2022), 578 (), 151953CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Chem. processes using heterogeneous photocatalytic systems are widely used for the synthesis of valuable fine chems. To improve these chem. processes both environmental and energy aspects must be kept in mind for favorable reaction conditions, such as optimum temp. and atm. pressure. In this study, plasmonic Au nanoparticles (Au NP) dispersed over TiO2 photocatalyst with different phases of TiO2 (amorphous, anatase and rutile) have been synthesized by using a facile sol-gel method followed by calcination for the photocatalytic oxidn. of benzyl alc. (BnOH) to benzaldehyde (BzH) under visible light irradn. at ambient conditions. The best photocatalyst exhibits high surface area and excellent catalytic conversion efficiency (96%) for the oxidn. of BnOH to BzH in less reaction time using a green solvent, acetonitrile at room temp. The detailed optimization of reaction parameters was performed for alc. conversion. In addn. the corresponding green metrics parameters were also calcd. The photocatalyst also shows excellent stability and reusability for multiple cycles. This work suggests that the Au-TiO2 catalyst provides a novel green and sustainable approach for the selective and efficient aerobic oxidn. of BnOH to BzH under visible light irradn. Furthermore, the impact of different phases of TiO2 on the photocatalytic activity has also been discussed.
- 29Kumar, A.; Shankar, K. R.; Kumar, A.; Harith, G.; Krishnan, V. Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteins. J. Environ. Chem. Eng. 2021, 9, 105147 DOI: 10.1016/j.jece.2021.105147Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjvFKru78%253D&md5=88230008129d52575c8a2ced0f6fe2b6Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteinsKumar, Ajay; Shankar, Konathala Ravi; Kumar, Ashish; Harith, Gurunarayanan; Krishnan, VenkataJournal of Environmental Chemical Engineering (2021), 9 (2), 105147CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)In this work, the interaction of different proteins with two dimensional (2D) graphitic carbon nitride (GCN) nanosheets decorated with gold nanoparticles (Au NP) is reported along with their influence in controlling the visible-light-induced photocatalytic activity. The decoration of Au NP on 2D GCN nanosheets improves the photocatalytic activity as Au NP plays an important role in trapping and storing the conduction band electrons of GCN nanosheets. The structural, morphol. and optical properties of Au-GCN (AGCN) nanocomposite have been investigated using scattering and spectroscopic techniques. Methylene blue (MB) dye was chosen as a representative system for the studying of visible-light-induced photocatalytic activity of AGCN nanocomposite in the presence of different proteins. Bovine serum albumin (BSA), trypsin and cytochrome C having different chain lengths and physicochem. properties were used to control the kinetics of the photocatalytic activity of GCN and AGCN nanocomposites. Due to the simultaneous competitive adsorption of MB and proteins, the photocatalytic activity of the nanocomposites got enhanced in the presence of BSA, while it got inhibited or slowed down in the presence of trypsin and cytochrome C, resp. The obsd. photocatalytic activity could be correlated with the surface charges present on the proteins and the mechanistic understanding developed in this study can be beneficial in controlling the kinetics of the photocatalytic activity of semiconductor-based photocatalysts using proteins as activators or inhibitors.
- 30Kumar, A.; Singla, Y.; Sharma, M.; Bhardwaj, A.; Krishnan, V. Two dimensional S-scheme Bi2WO6–TiO2–Ti3C2 nanocomposites for efficient degradation of organic pollutants under natural sunlight. Chemosphere 2022, 308, 136212 DOI: 10.1016/j.chemosphere.2022.136212Google Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XisFGms73O&md5=e2c5ed0e14cc5d5b0272a0c6e569c4c3Two dimensional S-scheme Bi2WO6-TiO2-Ti3C2 nanocomposites for efficient degradation of organic pollutants under natural sunlightKumar, Ashish; Singla, Yash; Sharma, Manisha; Bhardwaj, Akhil; Krishnan, VenkataChemosphere (2022), 308 (Part_1), 136212CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)Two-dimensional (2D) materials have fascinated the researchers to exploit their properties including large surface area, ability to act as a support and to form face-to-face interfacial contact with other 2D materials for fabricating efficient photocatalytic materials. In this work, Bi2WO6, TiO2 and Ti3C2 nanosheets have been used synthesizing different series of binary Bi2WO6-TiO2 and ternary Bi2WO6-TiO2-Ti3C2 2D nanocomposites by an electrostatic self-assembly synthesis route. The as-prepd. pristine materials and binary and ternary nanocomposites were characterized by different structural, morphol. and compositional characterization techniques to confirm their successful synthesis and 2D morphol. It was found that the optimized Bi2WO6-TiO2 (20 wt%) and Bi2WO6-TiO2 (20 wt%)-Ti3C2 (5 wt%) nanocomposites showed 97.0% and 98.5% degrdn. of methyl green in 80 min and 40 min, resp., which was higher than their pristine counterparts. The enhanced activity was credited to the large surface area offered by 2D nanocomposites, pollutant adsorption and enhanced photogenerated charge sepn. and transfer facilitated by S-scheme mechanism and face-to-face interfacial contact of different components of these nanocomposites. This work delivers an example of highly efficient 2D nanocomposites and discusses the role of Ti3C2 as an electron acceptor in S-scheme photocatalytic system.
- 31Zhang, W.; Ma, Y.; Zhu, X.; Liu, S.; An, T.; Bao, J.; Hu, X.; Tian, H. Fabrication of Ag decorated g-C3N4/LaFeO3 Z-scheme heterojunction as highly efficient visible-light photocatalyst for degradation of methylene blue and tetracycline hydrochloride. J. Alloys Compd. 2021, 864, 158914 DOI: 10.1016/j.jallcom.2021.158914Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjtV2rsL0%253D&md5=5978533798cacd07740f0c9d78cae12dFabrication of Ag decorated g-C3N4/LaFeO3 Z-scheme heterojunction as highly efficient visible-light photocatalyst for degradation of methylene blue and tetracycline hydrochlorideZhang, Weijin; Ma, Yongxiang; Zhu, Xiuhua; Liu, Shujie; An, Tao; Bao, Jinyu; Hu, Xiaoying; Tian, HongweiJournal of Alloys and Compounds (2021), 864 (), 158914CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)The discharge of industrial wastewater poses serious concerns to the environment and human health. Therefore, urgent development of simple and efficient catalysts for removal of pollutants is required. In this study, a novel ternary nanocomposite Ag/g-C3N4/LaFeO3 (A/CN/LFO) was synthesized for the degrdn. of dye and pharmaceutical wastewater. The catalyst was prepd. by decorating Ag nanoparticles (NPs) on g-C3N4/LaFeO3 (CN/LFO) Z-scheme heterojunction and formation of Schottky junctions with LaFeO3 (LFO) and g-C3N4 (CN). The formed hybrid structure between metal and Z-scheme heterojunction induced directional transfer of electrons or holes from the Z-scheme heterojunction to metal, providing max. sepn. between electrons and holes for more efficient redox reactions. Consequently, the ternary nanocomposite displayed optimized efficiencies toward the photocatalytic degrdn. of methylene blue (MB) and tetracycline hydrochloride (TC) under visible-light irradn., estd. to 98.97% (90 min) and 94.93% (120 min), resp. These values were almost 4.81 times and 3.88 times higher than those of pristine LaFeO3, resp. The charge transfer mechanism and pollutant degrdn. pathway were also studied. The data revealed that Ag decorated Z-scheme heterojunction showed efficient light absorption and sepn. of photogenerated carriers, which might be useful for large-scale practical applications related to wastewater treatment and pollution control.
- 32Tian, H.; Wan, C.; Xue, X.; Hu, X.; Wang, X. Effective Electron Transfer Pathway of the Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity under Visible Light. Catalysts 2017, 7, 156, DOI: 10.3390/catal7050156Google Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFymtbfI&md5=4d51f7aea907265a4c08f8a19521765fEffective electron transfer pathway of the ternary TiO2/RGO/Ag nanocomposite with enhanced photocatalytic activity under visible lightTian, Hongwei; Wan, Chenxing; Xue, Xin; Hu, Xiaoying; Wang, XiaoyiCatalysts (2017), 7 (5), 156/1-156/15CODEN: CATACJ; ISSN:2073-4344. (MDPI AG)Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous TiO2/RGO/Ag (MTGA) nanocomposite exhibited superior photocatalytic performance for the degrdn. of methylene blue (MB) under visible light, and the degrdn. rate reached 0.017 min-1, which was 3.4-times higher than that of MTG. What is more, the degrdn. rate of MTGA nanocomposite after three cycle times is 91.2%, and the compn. is unchanged. In addn., we found that the OH·, h+ and esp. O2·- contribute to the high photocatalytic activity of MTGA for MB degrdn. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR) to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the sepn. efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance.
- 33Tian, H.; Shen, K.; Hu, X.; Qiao, L.; Zheng, W. N, S co-doped graphene quantum dots-graphene-TiO2 nanotubes composite with enhanced photocatalytic activity. J. Alloys Compd. 2017, 691, 369– 377, DOI: 10.1016/j.jallcom.2016.08.261Google Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsV2is7zI&md5=65cf4cf9e5551f25527360df4484ac1bN, S co-doped graphene quantum dots-graphene-TiO2 nanotubes composite with enhanced photocatalytic activityTian, Hongwei; Shen, Kai; Hu, Xiaoying; Qiao, Liang; Zheng, WeitaoJournal of Alloys and Compounds (2017), 691 (), 369-377CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)N, S co-doped graphene quantum dots (N, S-GQDs) -reduced graphene oxide- (rGO) -TiO2 nanotubes (TiO2NT) composites were prepd. by a facile alk. hydrothermal reaction and phys. stirring process. The apparent rate const. of the N, S-GQDs + 10%rGO + TiO2NT composite, exhibiting the highest photodegrdn. efficiency, is 1.8 times and 16.3 times higher than those of 10% rGO + TiO2NT and pure TiO2NT, resp., for the degrdn. of methyl orange (MO) under visible light irradn. (λ > 400 nm). Our work could provide new insights into the fabrication of GQDs-semiconductor composites as high performance photocatalysts and broaden the range of doped GQDs widely used for environmental protection.
- 34Meng, Z.; Zhou, B.; Xu, J.; Li, Y.; Hu, X.; Tian, H. Heterostructured Nitrogen and Sulfur co-doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic Activity. Chem. Res. Chin. Univ. 2020, 36, 1045– 1052, DOI: 10.1007/s40242-020-0175-2Google Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFCht7rN&md5=13d04a8d4aa20c8a3f6dd7b744508dd2Heterostructured Nitrogen and Sulfur Co-doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic ActivityMeng, Zeshuo; Zhou, Bo; Xu, Jian; Li, Yaxin; Hu, Xiaoying; Tian, HongweiChemical Research in Chinese Universities (2020), 36 (6), 1045-1052CODEN: CRCUED; ISSN:1005-9040. (Jilin University)Conventional titanium dioxide(TiO2) photocatalyst could absorb only UV light due to its wide bandgap. In this paper, black TiO2 with narrow bandgap was prepd. by introducing oxygen vacancies. Meanwhile, nitrogen(N) and sulfur(S) elements were doped to further broaden the visible light response range of TiO2(NS-BT), and then heterostructured N,S-doped black TiO2/g-C3N4(CN/NS-BT) was successfully constructed by easily accessible route. The formation of CN/NS-BT heterojunction structure increased the generation and sepn. efficiency of photogenerated electron-hole pairs, as well as accelerated the transfer rate of the carriers. The as-prepd. CN/NS-BT exhibited excellent photocatalytic performance towards the degrdn. of Rhodamine B(RhB) under visible light irradn. with satisfactory stability. The apparent reaction rate const. of CN/NS-BT(0.0079) was 15.8-fold higher than that of com. P25(0.0005). The structure, morphol., chem. compn. and optical properties of the as-prepd. CN/NS-BT were characterized by various anal. methods, and possible photocatalytic enhancement mechanism was proposed. Overall, CN/NS-BT composites look promising as photocatalytic material for future environmental treatment.
- 35Santos, L. M.; Machado, W. A.; França, M. D.; Borges, K. A.; Paniago, R. M.; Patrocinio, A. O. T.; Machado, A. E. H. Structural characterization of Ag-doped TiO2 with enhanced photocatalytic activity. RSC Adv. 2015, 5, 103752– 103759, DOI: 10.1039/C5RA22647CGoogle Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvVygtrrK&md5=7ed281e717d9fa2f0761a9499588077fStructural characterization of Ag-doped TiO2 with enhanced photocatalytic activitySantos, Lidiaine M.; Machado, Werick A.; Franca, Marcela D.; Borges, Karen A.; Paniago, Roberto M.; Patrocinio, Antonio O. T.; Machado, Antonio E. H.RSC Advances (2015), 5 (125), 103752-103759CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)As the amt. of silver is increased, the resulting TiO2 nanoparticles exhibit smaller particle size (from 27 nm for bare TiO2 to 12 nm for TiO2-Ag 5.0%) and larger surface area. XPS confirms that during the sintering step of the resultant powder at 400°C for 5 h, ca. 34% of the silver content is converted to Ag0via thermal decompn. of Ag2O. The data also indicates the presence of highly oxidized silver species, such as Ag2+ and Ag3+. X-ray diffractograms and Raman spectroscopy confirm that the cryst. structure of the TiO2 matrix corresponds to the anatase polymorph; however, the presence of the dopant leads to an increase in the system disorder due to a higher concn. of oxygen vacancies, as also confirmed by XPS. TiO2-Ag 5.0% exhibited the highest photocatalytic activity towards mineralization of the E102 tartrazine azo-dye, being 78% faster than bare TiO2 at optimum pH conditions (pH = 6.9). Upon light excitation, the oxidized silver cations are reduced to Ag0, leading to an improvement in visible light absorption due to the surface plasmon resonance effect. The recycling of the photocatalyst showed that the enhanced photocatalytic activity is maintained, which can be assocd. with the redn. of charge recombination at the oxide surface and the enhanced visible light harvesting.
- 36Chakhtouna, H.; Benzeid, H.; Zari, N.; Qaiss, A. e. k.; Bouhfid, R. Recent progress on Ag/TiO2 photocatalysts: photocatalytic and bactericidal behaviors. Environ. Sci. Pollut. Res. 2021, 28, 44638– 44666, DOI: 10.1007/s11356-021-14996-yGoogle Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFegtrbO&md5=b1099342b50cac034c852c8e03fd3dceRecent progress on Ag/TiO2 photocatalysts: photocatalytic and bactericidal behaviorsChakhtouna, Hanane; Benzeid, Hanane; Zari, Nadia; Qaiss, Abou el kacem; Bouhfid, RachidEnvironmental Science and Pollution Research (2021), 28 (33), 44638-44666CODEN: ESPLEC; ISSN:0944-1344. (Springer)A review. Abstr.: For many decades, titanium dioxide (TiO2) semiconductor has been extensively applied in several environmental applications due to its higher photocatalytic performances toward different org. pollutants, pharmaceutical compds., and bacteria. However, its shortfall response to visible light, and the expeditious recombination rate of the photogenerated electron-hole pairs, hampers its utilization. Doping TiO2 semiconductor with silver nanoparticles is a sound strategy to (1) extend its photocatalytic activity to visible light, (2) prevent the electron/holes pairs recombination due to the formation of the Schottky barrier at the interfaces with TiO2 that act as an electron-trapping center, and (3) enhance its bactericide performances. This focuses on the recent progress on silver-doped titanium dioxide (Ag/TiO2)-based photocatalysts. It addresses a wide range of Ag/TiO2 synthesis techniques, their physicochem. properties and discusses thoroughly the important role of silver (Ag) nanoparticles in enhancing the removal capacity and antibacterial performances of the Ag/TiO2 photocatalysts.
- 37Gogoi, D.; Namdeo, A.; Golder, A. K.; Peela, N. R. Ag-doped TiO2 photocatalysts with effective charge transfer for highly efficient hydrogen production through water splitting. Int. J. Hydrogen Energy 2020, 45, 2729– 2744, DOI: 10.1016/j.ijhydene.2019.11.127Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitlajtbbO&md5=65ca3a673eead3fcb79bb9f1138ac1afAg-doped TiO2 photocatalysts with effective charge transfer for highly efficient hydrogen production through water splittingGogoi, Devipriya; Namdeo, Ashutosh; Golder, Animes Kumar; Peela, Nageswara RaoInternational Journal of Hydrogen Energy (2020), 45 (4), 2729-2744CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)The development of efficient metal doped semiconductors for solar energy harvesting to produce hydrogen has attracted significant attention. Herein, the H2 generation over Ag-doped TiO2 photocatalyst, synthesized using a simple and cost-effective method based on chem. redn., was reported. The Ag/TiO2 exhibited an absorption peak in the visible region and the redn. of the bandgap to 2.5 eV due to surface plasmonic resonance (SPR). XPS revealed the presence of oxygen vacancies and 11% of Ag in Ti-Ag-O phase. The effect of reaction time and photocatalyst loading in the absence and presence of sacrificial reagents (alcs. and sulfur) on water splitting was studied and compared the activity of Ag/TiO2 with that of bare TiO2. The H2 prodn. rate of 23.5 mmol g-1 h-1 (with an apparent quantum yield of 19%), over 1.5Ag/TiO2, was the highest ever reported so far. The obsd. higher activity could mainly be attributed to the existence of oxygen vacancies and the Ti-Ag-O phase. The photocatalyst was stable for three consecutive cycles in both the presence and absence of sacrificial reagents. This study offers new insights into the rational design of metal-support hybrid structures for hydrogen prodn. through photocatalytic water splitting.
- 38Varma, R. S.; Thorat, N.; Fernandes, R.; Kothari, D. C.; Patel, N.; Miotello, A. Dependence of photocatalysis on charge carrier separation in Ag-doped and decorated TiO2 nanocomposites. Catal. Sci. Technol. 2016, 6, 8428– 8440, DOI: 10.1039/C6CY01605GGoogle Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1ygur%252FL&md5=86ed397216f3e28651795bde0dd65ad4Dependence of photocatalysis on charge carrier separation in Ag-doped and decorated TiO2 nanocompositesVarma, Ranjana S.; Thorat, Nirmala; Fernandes, R.; Kothari, D. C.; Patel, N.; Miotello, A.Catalysis Science & Technology (2016), 6 (24), 8428-8440CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)Two model Ag-TiO2 nanocomposite systems have been investigated with the aim of understanding the relationship between the photocatalytic efficiency and the contributions of various structures resulting in charge carrier sepn., charge transfer and extension of light absorption to the visible range. The first model system is based on a composite scheme consisting of TiO2 decorated with Ag nanoparticles (NPs). The second composite scheme consists of TiO2 simultaneously doped and decorated with Ag NPs. Ag-TiO2 nanocomposites contg. various concns. (0.5 to 6 at%) of Ag nanoparticles were prepd., and the photocatalytic degrdn. of p-nitrophenol (PNP) and methylene blue (MB) were investigated. Compared to the Ag-decorated samples, the Ag-doped and decorated samples show enhanced activity due to the synergistic effects of the Schottky barrier, doping and the anatase + brookite mixed phase. It was obsd. from PL and fluorescence lifetime studies that the charge carrier lifetime correlates with the relative photonic efficiency of the photocatalytic activity. An optimum Ag concn. is required to obtain the max. lifetime of the photo-generated charges. The photocatalytic activity does not show any correlation to the amt. of visible light absorption, to plasmonic effects, or to band-gap redn. Decorating with silver nanoparticles aids electron transfer and creates electron traps in the form of oxygen vacancies on the surface of TiO2. For the Ag-TiO2 system, the photocatalytic activity is directly proportional to the lifetime of the photogenerated charge carrier.
- 39Zhao, Z.-J.; Hwang, S. H.; Jeon, S.; Hwang, B.; Jung, J.-Y.; Lee, J.; Park, S.-H.; Jeong, J.-H. Three-dimensional plasmonic Ag/TiO2 nanocomposite architectures on flexible substrates for visible-light photocatalytic activity. Sci. Rep. 2017, 7, 8915 DOI: 10.1038/s41598-017-09401-zGoogle Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cbgtlWgug%253D%253D&md5=27318cb0ca29efb36078d50430cffa31Three-dimensional plasmonic Ag/TiO2 nanocomposite architectures on flexible substrates for visible-light photocatalytic activityZhao Zhi-Jun; Park Sang-Hu; Zhao Zhi-Jun; Hwang Soon Hyoung; Jeon Sohee; Hwang Boyeon; Jung Joo-Yun; Lee Jihye; Jeong Jun-Ho; Hwang Soon Hyoung; Hwang BoyeonScientific reports (2017), 7 (1), 8915 ISSN:.In this study, a periodic three-dimensional (3D) Ag/TiO2 nanocomposite architecture of nanowires was fabricated on a flexible substrate to enhance the plasmonic photocatalytic activity of the composite. Layer-by-layer nanofabrication based on nanoimprint lithography, vertical e-beam evaporation, nanotransfer, and nanowelding was applied in a new method to create different 3D Ag/TiO2 nanocomposite architectures. The fabricated samples were characterized by scanning electron microscopy, transmission electron microscopy, focused ion-beam imaging, X-ray photoelectron spectrometry, and UV-visible spectroscopy. The experiment indicated that the 3D nanocomposite architectures could effectively enhance photocatalytic activity in the degradation of methylene blue solution under visible light irradiation. We believe that our method is efficient and stable, which could be applied to various fields, including photocatalysis, solar energy conversion, and biotechnology.
- 40Zhang, S.; Wang, L.; Liu, C.; Luo, J.; Crittenden, J.; Liu, X.; Cai, T.; Yuan, J.; Pei, Y.; Liu, Y. Photocatalytic wastewater purification with simultaneous hydrogen production using MoS2 QD-decorated hierarchical assembly of ZnIn2S4 on reduced graphene oxide photocatalyst. Water Res. 2017, 121, 11– 19, DOI: 10.1016/j.watres.2017.05.013Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXnslOnu7o%253D&md5=edb6f2d5262c75df2d620cdebb71e0d9Photocatalytic wastewater purification with simultaneous hydrogen production using MoS2 QD-decorated hierarchical assembly of ZnIn2S4 on reduced graphene oxide photocatalystZhang, Shuqu; Wang, Longlu; Liu, Chengbin; Luo, Jinming; Crittenden, John; Liu, Xia; Cai, Tao; Yuan, Jili; Pei, Yong; Liu, YutangWater Research (2017), 121 (), 11-19CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)It is attractive to photocatalytically purify wastewater and simultaneously convert solar energy into clean hydrogen energy. However, it is still a challenge owing to the relatively low photocatalytic efficiency of photocatalysts. In this study, we synthesized a molybdenum disulfide (MoS2) quantum dot-decorated 3D nanoarchitecture (MoS2QDs) of indium zinc sulfide (ZnIn2S4) and reduced grapheme oxide (MoS2QDs@ZnIn2S4@RGO) photocatalyst using a simple solvothermal method. The RGO promotes the electron transfer, and the highly dispersed MoS2QDs provides numerous catalytic sites. The photocatalytic purifn. of rhodamine B (RhB), eosin Y (EY), fulvic acid (FA), methylene blue (MB) and p-nitrophenol (PNP) in simulated wastewaters were further tested. The degrdn. efficiencies and TOC removal were 91% and 75% for PNP, 92.2% and 72% for FA, 98.5% and 80% for MB, 98.6% and 84% for EY, and 98.8% and 88% for RhB, resp. (Corganics = 20 mg/L, Ccatalyst = 1.25 g/L, t = 12 h, Ilight = 3.36 × 10-5 E L-1 s-1). Among these tests, the highest hydrogen prodn. was achieved (45 μmol) during RhB degrdn. Both exptl. and calculational results prove that lower LUMO (lowest unoccupied mol. orbit) level of org. mols. was available for transferring electrons to catalysts, resulting in more efficient hydrogen prodn. Significantly, the removal efficiencies of natural org. substances in actual river water reached 76.3-98.4%, and COD reduced from 32 to 16 mg/L with 13.8 μmol H2 prodn. after 12 h.
- 41Hippargi, G.; Anjankar, S.; Krupadam, R. J.; Rayalu, S. S. Simultaneous wastewater treatment and generation of blended fuel methane and hydrogen using Au-Pt/TiO2 photo-reforming catalytic material. Fuel 2021, 291, 120113 DOI: 10.1016/j.fuel.2020.120113Google Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvVejt7g%253D&md5=2f5229cbf1d286b70ef68ed6db6f0405Simultaneous wastewater treatment and generation of blended fuel methane and hydrogen using Au-Pt/TiO2 photo-reforming catalytic materialHippargi, Girivyankatesh; Anjankar, Swapna; Krupadam, Reddithota J.; Rayalu, Sadhana S.Fuel (2021), 291 (), 120113CODEN: FUELAC; ISSN:0016-2361. (Elsevier Ltd.)In this work, we report the generation of blended fuel of hydrogen and methane by using simultaneous photocatalysis and photoreforming reactions. A photocatalyst Au-Pt/TiO2 has been designed rationally and synthesized for the efficient electron transfer from Au to Pt and surface ensemble effects which improved the yield of hydrogen and methane. The distribution of Au and Pt nanoparticles were detd. by using electron microscope investigations. The nanocatalyst was further studied for structural elucidation by using X-ray diffraction and optical spectroscopy. It was obsd. that the nanoparticles of Au and Pt dispersed on the TiO2 responsible for facilitation of electron transfer in UV and visible region. This mechanism easily excites TiO2 for catalytic transformation of carboxylic acid to hydrogen and methane. Under UV-Visible light (400 W) the newly developed catalyst reports effective prodn. of hydrogen and methane at the rate of 9386 and 2208μmol/h (14725 and 62579μmol/h/g), resp. from acetic acid with apparent quantum yield of 3.85% at the bandgap of 3.2 eV. This catalytic prodn. of hydrogen and methane (hythane gas) was examd. using acetic acid enriched wastewater. The blended fuel obtained can be used in automobiles as the fuel with lower emissions compared with methane alone as the fuel.
- 42Jeon, T. H.; Koo, M. S.; Kim, H.; Choi, W. Dual-Functional Photocatalytic and Photoelectrocatalytic Systems for Energy- and Resource-Recovering Water Treatment. ACS Catal. 2018, 8, 11542– 11563, DOI: 10.1021/acscatal.8b03521Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVWrtb%252FF&md5=98081e22770561c5605c2a4b7c28d187Dual-Functional Photocatalytic and Photoelectrocatalytic Systems for Energy- and Resource-Recovering Water TreatmentJeon, Tae Hwa; Koo, Min Seok; Kim, Hyejin; Choi, WonyongACS Catalysis (2018), 8 (12), 11542-11563CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. The solar-driven photo(electro)catalytic process is a key technol. for utilization of solar energy. It is being intensively investigated for application to environmental remediation and solar fuel prodn. Although both environmental and energy applications operate on the basis of the same principle of photoinduced interfacial charge transfer, most previous studies have focused on either the environmental or energy process only since these two processes require very different catalyst properties and reaction conditions. This Perspective describes a dual-functional photo(electro)catalytic process that enables water treatment along with the simultaneous recovery of energy (e.g., H2 and H2O2) or resources (e.g., metal ions) and discusses the status and perspectives of this emerging technol. The essential feature of the process is to utilize the hole oxidn. power for the degrdn. of water pollutants and the electron redn. power for the recovery of energy and resources from wastewaters at the same time. Various PC, PEC, and photovoltaic-driven electrochem. (PV-EC) processes with different dual-functional purposes (e.g., pollutant removal combined with H2 or H2O2 prodn., heavy-metal recovery, denitrification, fuel cell) are introduced and discussed. The reviewed technol. should offer chances for the development of next-generation water treatment processes based on the water-solar energy nexus.
- 43Pitchaimuthu, S.; Sridharan, K.; Nagarajan, S.; Ananthraj, S.; Robertson, P.; Kuehnel, M. F.; Irabien, Á.; Maroto-Valer, M. Solar Hydrogen Fuel Generation from Wastewater─Beyond Photoelectrochemical Water Splitting: A Perspective. Energies 2022, 15, 7399, DOI: 10.3390/en15197399Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xis1Khs7nN&md5=48bac680bd059fb285817d22979f387dSolar Hydrogen Fuel Generation from Wastewater-Beyond Photoelectrochemical Water Splitting: A PerspectivePitchaimuthu, Sudhagar; Sridharan, Kishore; Nagarajan, Sanjay; Ananthraj, Sengeni; Robertson, Peter; Kuehnel, Moritz F.; Irabien, Angel; Maroto-Valer, MercedesEnergies (Basel, Switzerland) (2022), 15 (19), 7399CODEN: ENERGA; ISSN:1996-1073. (MDPI AG)A review. Green hydrogen-a carbon-free renewable fuel-has the capability to decarbonise a variety of sectors. The generation of green hydrogen is currently restricted to water electrolyzers. The use of freshwater resources and crit. raw materials, however, limits their use. Alternative water splitting methods for green hydrogen generation via photocatalysis and photoelectrocatalysis (PEC) have been explored in the past few decades; however, their com. potential still remains unexploited due to the high hydrogen generation costs. Novel PEC-based simultaneous generation of green hydrogen and wastewater treatment/high-value product prodn. is therefore seen as an alternative to conventional water splitting. Interestingly, the org./inorg. pollutants in wastewater and biomass favorably act as electron donors and facilitate the dual-functional process of recovering green hydrogen while oxidising the org. matter. The generation of green hydrogen through the dual-functional PEC process opens up opportunities for a circular economy. It further enables the end-of-life commodities to be reused, recycled and resourced for a better life-cycle design while being economically viable for commercialisation. This review brings together and critically analyses the recent trends towards simultaneous wastewater treatment/biomass reforming while generating hydrogen gas by employing the PEC technol. We have briefly discussed the tech. challenges assocd. with the tandem PEC process, new avenues, techno-economic feasibility and future directions towards achieving net neutrality.
- 44Liu, J.; An, T.; Li, G.; Bao, N.; Sheng, G.; Fu, J. Preparation and characterization of highly active mesoporous TiO2 photocatalysts by hydrothermal synthesis under weak acid conditions. Microporous Mesoporous Mater. 2009, 124, 197– 203, DOI: 10.1016/j.micromeso.2009.05.009Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXnvVCnurk%253D&md5=720f13589938f283bb9a5c5f63bcf17dPreparation and characterization of highly active mesoporous TiO2 photocatalysts by hydrothermal synthesis under weak acid conditionsLiu, Jikai; An, Taicheng; Li, Guiying; Bao, Ningzhong; Sheng, Guoying; Fu, JiamoMicroporous and Mesoporous Materials (2009), 124 (1-3), 197-203CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier Inc.)Mesoporous TiO2 photocatalysts have been synthesized in acetic acid aq. solns. by using the amphiphilic triblock copolymer (Pluronic P123) template. The prepd. photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption/desorption anal. The phase and structural qualities of the obtained mesoporous TiO2 have been improved by using hydrothermal treatment. The hydrolysis reaction of titanium sources has been controlled by using a low concd. acetic acid aq. soln. used as both hydrolytic retardants and acid catalysts because of the strong chelating effect and acidity of acetic acid. The obtained mesoporous TiO2 exhibits uniform mesoporous structure with different mean pore sizes of up to 9.0 nm. The photocatalytic activity of the obtained photocatalysts was investigated, using di-Me phthalate as a modal pollutant. Over 90% of di-Me phthalate can be photocatalytically degraded within 2 h under UV irradn. in the presence of the obtained photocatalysts with a concn. of 2 g/L. The calcination temp. is the most remarkable factor that can affect the ultimate photocatalytic activity of the prepd. photocatalysts.
- 45Naik, B.; Desai, V.; Kowshik, M.; Prasad, V. S.; Fernando, G. F.; Ghosh, N. N. Synthesis of Ag/AgCl–mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coli. Particuology 2011, 9, 243– 247, DOI: 10.1016/j.partic.2010.12.001Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXotVGntbw%253D&md5=4998f07bb3de2377f751f98677a1921bSynthesis of Ag/AgCl-mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coliNaik, Bhanudas; Desai, Vilas; Kowshik, Meenal; Prasad, Vadakkethonippurathu Sivankutty; Fernando, Gerard Franklyn; Ghosh, Narendra NathParticuology (2011), 9 (3), 243-247CODEN: PARTC5; ISSN:1674-2001. (Elsevier B.V.)Simple aq. soln.-based chem. methods have been developed for the synthesis of Ag/AgCl nanoparticle-mesoporous silica nanocomposites. Ag loading in the mesoporous silica was accomplished using a wet-impregnation method. The AgCl-mesoporous silica nanocomposite material (AgCl-mSi) was synthesized by using a one pot' method. Synthesized materials were characterized using X-ray diffraction, N2 adsorption-desorption anal. and high-resoln. transmission electron microscopy. Antibacterial activity of the synthesized materials was investigated against Escherichia coli (E. coli) using the conventional plate-count method. All the materials showed high antibacterial activity even when the percentage loading of Ag in the nanocomposite was as low as 10 wt%.
- 46Yuan, J.; Chen, M.; Shi, J.; Shangguan, W. Preparations and photocatalytic hydrogen evolution of N-doped TiO2 from urea and titanium tetrachloride. Int. J. Hydrogen Energy 2006, 31, 1326– 1331, DOI: 10.1016/j.ijhydene.2005.11.016Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsFKqsrY%253D&md5=62ee803ccc7fbe514746b87cd6d8c604Preparations and photocatalytic hydrogen evolution of N-doped TiO2 from urea and titanium tetrachlorideYuan, Jian; Chen, Mingxia; Shi, Jianwei; Shangguan, WenfengInternational Journal of Hydrogen Energy (2006), 31 (10), 1326-1331CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)Nitrogen (N)-doped TiO2 samples with high sp. surface areas were directly prepd. by heating the mixt. of urea and TiO2, where the TiO2 was obtained with titanium tetrachloride as precursor. The absorption spectrum of the N-doped TiO2 shifted to wavelength up to 600 nm with increasing urea contents. X-ray photoelectron spectroscopic measurements showed that the N presented in TiO2 was in the state of both molecularly chemisorbed N2 and substituted N. While both of them contribute to the response to visible light, the latter gave the prepd. samples with hydrogen evolution under visible light. The apparent photocatalytic activity of water splitting demonstrated as high amt. of H2 evolution was partly due to the phase transformation from anatase to rutile for the N-doped TiO2.
- 47Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B: Condens. Matter Mater. Phys. 1999, 59, 1758– 1775, DOI: 10.1103/PhysRevB.59.1758Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXkt12nug%253D%253D&md5=78a73e92a93f995982fc481715729b14From ultrasoft pseudopotentials to the projector augmented-wave methodKresse, G.; Joubert, D.Physical Review B: Condensed Matter and Materials Physics (1999), 59 (3), 1758-1775CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived. The total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addn., crit. tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed-core all-electron methods. These tests include small mols. (H2, H2O, Li2, N2, F2, BF3, SiF4) and several bulk systems (diamond, Si, V, Li, Ca, CaF2, Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.
- 48Kresse, G.; Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 1996, 6, 15– 50, DOI: 10.1016/0927-0256(96)00008-0Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XmtFWgsrk%253D&md5=779b9a71bbd32904f968e39f39946190Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis setKresse, G.; Furthmuller, J.Computational Materials Science (1996), 6 (1), 15-50CODEN: CMMSEM; ISSN:0927-0256. (Elsevier)The authors present a detailed description and comparison of algorithms for performing ab-initio quantum-mech. calcns. using pseudopotentials and a plane-wave basis set. The authors will discuss: (a) partial occupancies within the framework of the linear tetrahedron method and the finite temp. d.-functional theory, (b) iterative methods for the diagonalization of the Kohn-Sham Hamiltonian and a discussion of an efficient iterative method based on the ideas of Pulay's residual minimization, which is close to an order N2atoms scaling even for relatively large systems, (c) efficient Broyden-like and Pulay-like mixing methods for the charge d. including a new special preconditioning optimized for a plane-wave basis set, (d) conjugate gradient methods for minimizing the electronic free energy with respect to all degrees of freedom simultaneously. The authors have implemented these algorithms within a powerful package called VAMP (Vienna ab-initio mol.-dynamics package). The program and the techniques have been used successfully for a large no. of different systems (liq. and amorphous semiconductors, liq. simple and transition metals, metallic and semi-conducting surfaces, phonons in simple metals, transition metals and semiconductors) and turned out to be very reliable.
- 49Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B: Condens. Matter Mater. Phys. 1996, 54, 11169– 11186, DOI: 10.1103/PhysRevB.54.11169Google Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xms1Whu7Y%253D&md5=9c8f6f298fe5ffe37c2589d3f970a697Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis setKresse, G.; Furthmueller, J.Physical Review B: Condensed Matter (1996), 54 (16), 11169-11186CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)The authors present an efficient scheme for calcg. the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrixes will be discussed. This approach is stable, reliable, and minimizes the no. of order Natoms3 operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special "metric" and a special "preconditioning" optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calcns. It will be shown that the no. of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order Natoms2 scaling is found for systems contg. up to 1000 electrons. If we take into account that the no. of k points can be decreased linearly with the system size, the overall scaling can approach Natoms. They have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large no. of different systems (liq. and amorphous semiconductors, liq. simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable.
- 50Perdew, J. P.; Chevary, J. A.; Vosko, S. H.; Jackson, K. A.; Pederson, M. R.; Singh, D. J.; Fiolhais, C. Atoms, molecules, solids, and surfaces: Applications of the generalized gradient approximation for exchange and correlation. Phys. Rev. B: Condens. Matter Mater. Phys. 1992, 46, 6671– 6687, DOI: 10.1103/PhysRevB.46.6671Google Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XlvFyks7c%253D&md5=e52b617f523b1a8c545707544ce01d05Atoms, molecules, solids, and surfaces: applications of the generalized gradient approximation for exchange and correlationPerdew, John P.; Chevary, J. A.; Vosko, S. H.; Jackson, Koblar A.; Pederson, Mark R.; Singh, D. J.; Fiolhais, CarlosPhysical Review B: Condensed Matter and Materials Physics (1992), 46 (11), 6671-87CODEN: PRBMDO; ISSN:0163-1829.Generalized gradient approxns. (GGA's) seek to improve upon the accuracy of the local-spin-d. (LSD) approxn. in electronic-structure calcns. Perdew and Wang have developed a GGA based on real-space cutoff of the spurious long-range components of the second-order gradient expansion for the exchange-correlation hole. Authors have found that this d. functional performs well in numerical tests for a variety of systems: Total energies of 30 atoms are highly accurate. Ionization energies and electron affinities are improved in a statistical sense, although significant interconfigurational and interterm errors remain. Accurate atomization energies are found for seven hydrocarbon mols., with a rms error per bond of 0.1 eV, compared with 0.7 eV for the LSD approxn. and 2.4 eV for the Hartree-Fock approxn. For atoms and mols., there is a cancellation of error between d. functionals for exchange and correlation, which is most striking whenever the Hartree-Fock result is furthest from expt. The surprising LSD underestimation of the lattice consts. of Li and Na by 3-4% is cor., and the magnetic ground state of solid Fe is restored. The work function, surface energy (neglecting the long-range contribution), and curvature energy of a metallic surface are all slightly reduced in comparison with LSD. Taking account of the pos. long-range contribution, authors find surface and curvature energies in good agreement with exptl. or exact values. Finally, a way is found to visualize and understand the nonlocality of exchange and correlation, its origins, and its phys. effects.
- 51Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865– 3868, DOI: 10.1103/PhysRevLett.77.3865Google Scholar51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XmsVCgsbs%253D&md5=55943538406ee74f93aabdf882cd4630Generalized gradient approximation made simplePerdew, John P.; Burke, Kieron; Ernzerhof, MatthiasPhysical Review Letters (1996), 77 (18), 3865-3868CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)Generalized gradient approxns. (GGA's) for the exchange-correlation energy improve upon the local spin d. (LSD) description of atoms, mols., and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental consts. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential.
- 52Monkhorst, H. J.; Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B: Condens. Matter Mater. Phys. 1976, 13, 5188– 5192, DOI: 10.1103/PhysRevB.13.5188Google ScholarThere is no corresponding record for this reference.
- 53Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P. Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study. Phys. Rev. B: Condens. Matter Mater. Phys. 1998, 57, 1505– 1509, DOI: 10.1103/PhysRevB.57.1505Google Scholar53https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXlsVarsQ%253D%253D&md5=9b4f0473346679cb1a8dce0ad7583153Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U studyDudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P.Physical Review B: Condensed Matter and Materials Physics (1998), 57 (3), 1505-1509CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)By taking better account of electron correlations in the 3d shell of metal ions in Ni oxide it is possible to improve the description of both electron energy loss spectra and parameters characterizing the structural stability of the material compared with local spin d. functional theory.
- 54Kim, S.; Ji, S.; Kim, K. H.; Roh, S. H.; Cho, Y.; Lee, C.-L.; Lee, K.-S.; Choi, D.-G.; Choi, H.; Kim, J. K.; Park, J. H. Revisiting surface chemistry in TiO2: A critical role of ionic passivation for pH-independent and anti-corrosive photoelectrochemical water oxidation. Chem. Eng. J. 2021, 407, 126929 DOI: 10.1016/j.cej.2020.126929Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFChtLbL&md5=a490d8920415f980cb22171f63590f0dRevisiting surface chemistry in TiO2: A critical role of ionic passivation for pH-independent and anti-corrosive photoelectrochemical water oxidationKim, Sungsoon; Ji, Seulgi; Kim, Kwang Hee; Roh, Seung Hun; Cho, Yoonjun; Lee, Chang-Lyoul; Lee, Kug-Seung; Choi, Dae-Geun; Choi, Heechae; Kim, Jung Kyu; Park, Jong HyeokChemical Engineering Journal (Amsterdam, Netherlands) (2021), 407 (), 126929CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)TiO2 photoanodes suffer from low catalytic activity and poor stability under acidic media for water oxidn. Here, pH-independent high-efficiency photoelectrochem. (PEC) water oxidn. and prolonged stability via simple ionic passivation of rutile TiO2 (rTiO2) surface are reported. The controlled surface passivation by hydroxide ions (OH-) onto the rTiO2 surface (OH-rTiO2) enables extraordinarily high PEC performance and long-term durability independent of the pH value of electrolyte. The OH-rTiO2 photoanode shows a charge transfer efficiency of ∼ 100% at 1.23 V vs. RHE over the entire pH range (pH 0 ∼ pH 14) without incorporation of any co-catalysts, hole scavengers, or over-layers, which implies that the mol. surface passivation by hydroxide ions successfully promotes the water oxidn. reaction pathway. According to the d. functional theory (DFT) calcns., the OH-rTiO2 surface can possess increased hydroxide ion coverage, faster decay of the pos. surface charge in acidic environments, and weakened H+ adsorption for pH > 7, which enable enhanced water oxidn. performance independent of the pH value of the electrolyte. Thus, the report proves that the ionic passivation by hydroxide ions can affect PEC performances and durability of photoanode materials for pH-universal photoelectrochem. water oxidn.
- 55Sanjinés, R.; Tang, H.; Berger, H.; Gozzo, F.; Margaritondo, G.; Levy, F. Electronic structure of anatase TiO2 oxide. J. Appl. Phys. 1994, 75, 2945– 2951, DOI: 10.1063/1.356190Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXit1Ontrg%253D&md5=853970b4a902d9558bc0c2906fc8d0ebElectronic structure of anatase TiO2 oxideSanjines, R.; Tang, H.; Berger, H.; Gozzo, F.; Margaritondo, G.; Levy, F.Journal of Applied Physics (1994), 75 (6), 2945-51CODEN: JAPIAU; ISSN:0021-8979.Photoemission spectroscopy was used to investigate the electronic structure of TiO2 anatase single crystals and polycryst. thin films. The stoichiometry and the degree of oxidn. of as-grown crystals, as-deposited films, as well as of thermally annealed samples in different atmospheres, were analyzed, based on the Ti 2p and O 1s core levels, with an energy resoln. of 0.4 eV. The exptl. d. of states (DOS) was found to be in agreement with the theor. DOS reported in the literature for anatase crystals, and shows some characteristics similar to the exptl. DOS reported for rutile crystals. In reduced samples, the exptl. DOS is characterized by intense emission in the region of O 2p bonding orbitals, and does not exhibit an appreciable d. of states in the band gap. As-grown crystals exhibit small band gap emission (a few percent of the valence band VB signal) at about 0.8 eV, which is attributed to Ti3+ (3d) defect states. Annealing the crystals at high temps. in O2 or subsequent thermal redn. in an Ar-H2 mixt. (95%-5%) produces nearly stoichiometric surfaces with smaller or undetectable d. of Ti3+ states. In addn., some redistribution of the spectral wt. is obsd. in the VB spectra.
- 56Bharti, B.; Kumar, S.; Lee, H.-N.; Kumar, R. Formation of oxygen vacancies and Ti 3+ state in TiO 2 thin film and enhanced optical properties by air plasma treatment. Sci. Rep. 2016, 6, 32355 DOI: 10.1038/srep32355Google Scholar56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsVChu73N&md5=335afc5714d6ad61382647447ae2ab26Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatmentBharti, Bandna; Kumar, Santosh; Lee, Heung-No; Kumar, RajeshScientific Reports (2016), 6 (), 32355CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+, Ti4+, O2-, oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 s. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was obsd. in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.
- 57Jaiswal, R.; Patel, N.; Kothari, D.; Miotello, A. Improved visible light photocatalytic activity of TiO2 co-doped with Vanadium and Nitrogen. Appl. Catal., B 2012, 126, 47– 54, DOI: 10.1016/j.apcatb.2012.06.030Google Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhtlaiur7N&md5=ef5570f8e64bfb6c63cec489470dff48Improved visible light photocatalytic activity of TiO2 co-doped with Vanadium and NitrogenJaiswal, R.; Patel, N.; Kothari, D. C.; Miotello, A.Applied Catalysis, B: Environmental (2012), 126 (), 47-54CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)V- and N-codoped TiO2 photo-catalyst is synthesized by sol-gel method to sensitize TiO2 to visible light. The concns. of V and N were varied and optimized to enhance photo-catalytic activity. To increase the active surface area, the cryst. powder was ball milled to obtain nanosized particles. The photo-catalysts were characterized by Micro-Raman, TEM, XPS and UV-visible (in diffused reflectance mode) techniques. The co-doped TiO2 photocatalyst displayed narrower band gap (2.3 eV) compared to singly doped TiO2 catalyst, V (2 at.%)-doped (2.42 eV), N (4 at.%)-doped (2.95 eV), and undoped TiO2 (3.13 eV). The photocatalytic activity for the degrdn. of Rhodamine B (an org. dye) under visible light irradn. obtained with co-doped TiO2 photo-catalyst is significantly better as compared to the undoped, V-doped, and N-doped TiO2. The incorporation of V and N in TiO2 lattice induces isolated energy levels near the conduction and valence bands, resp., causing an effective narrowing of the band gap. Due to the low dopants concns., these energy levels can also act as traps for photoexcited holes or electrons thus reducing the recombination between photo-generated charges. Both these effects, band narrowing and enhanced charge sepn. produce synergistic effects to increase the photocatalytic activity of V-N-codoped TiO2.
- 58Wint, T. H. M.; Smith, M. F.; Chanlek, N.; Chen, F.; Oo, T. Z.; Songsiriritthigul, P. Physical origin of diminishing photocatalytic efficiency for recycled TiO2 nanotubes and Ag-loaded TiO2 nanotubes in organic aqueous solution. Catalysts 2020, 10, 737, DOI: 10.3390/catal10070737Google Scholar58https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVShsL%252FJ&md5=5579289a4554a6ac8f9a2ff6994854e3Physical origin of diminishing photocatalytic efficiency for recycled TiO2 Nanotubes and Ag-Loaded TiO2 Nanotubes in organic aqueous solutionWint, Theint Hay Mar; Smith, Michael F.; Chanlek, Narong; Chen, Fuming; Oo, Than Zaw; Songsiriritthigul, PrayoonCatalysts (2020), 10 (7), 737CODEN: CATACJ; ISSN:2073-4344. (MDPI AG)Arrays of titania nanotubes (TiO2NTs) were developed by electrochem. anodization and doped with silver on their surface by photodeposition to achieve TiO2NTs/Ag. It is found that only anatase TiO2NTs were formed, with the preferential growth direction perpendicular to the titanium substrate, and with the length and diam. of ∼2μm and 90-120 nm, resp. The presence of Ag on the surface of TiO2NTs was also confirmed. The TiO2NTs and TiO2NTs/Ag were used as photocatalysts to decolorize the methylene blue (MB) aq. soln. The photodegrdn. efficiency (PDE) is as high as 83% for TiO2NTs and 98% for TiO2NTs/Ag photocatalysts. This work focused on the investigation of the stability and recyclability of these photocatalysts in terms of efficiency and its phys. origin by surface anal. using XPS. It is found that PDE diminishes from 83% to 76% in TiO2NTs upon eight recycling runs and from 98% to 80% in TiO2NTs/Ag upon six recycling runs. The XPS anal. revealed that the phys. origin of diminishing efficiency is the carbon contamination on the surface of recycled TiO2NTs and a combination of carbon contamination and Ag leaching in recycled TiO2NTs/Ag.
- 59Thiel, J.; Pakstis, L.; Buzby, S.; Raffi, M.; Ni, C.; Pochan, D. e. J.; Shah, S. I. Antibacterial properties of silver-doped titania. Small 2007, 3, 799– 803, DOI: 10.1002/smll.200600481Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXls1Wqurk%253D&md5=ca507d96435f1663b384f3279d87807eAntibacterial properties of silver-doped titaniaThiel, J.; Pakstis, L.; Buzby, S.; Raffi, M.; Ni, C.; Pochan, D. J.; Shah, S. IsmatSmall (2007), 3 (5), 799-803CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Silver-doped titania nanoparticles (see image) in specific concns. show a higher efficacy than pure silver nanoparticles towards the inhibition and annihilation of E. coli bacteria. The doped titania particles are synthesized via a sol-gel method. Antibacterial studies of the silver-doped titania particles in both a liq.-nutrient growth medium and on agar plates are shown; this approach may offer a simple low-cost method for fabricating antibacterial surfaces.
- 60Wagner, C.; Riggs, W.; Davis, L.; Moulder, J. Handbook of X-ray Photoelectron Spectroscopy, Muilenberg, G. E., Ed.; Perkin-Elmer Corporation: Eden Prairie, Minnesota, 1979; p 38.Google ScholarThere is no corresponding record for this reference.
- 61Vasil’kov, A. Y.; Dovnar, R. I.; Smotryn, S. M.; Iaskevich, N. N.; Naumkin, A. V. Plasmon resonance of silver nanoparticles as a method of increasing their antibacterial action. Antibiotics 2018, 7, 80, DOI: 10.3390/antibiotics7030080Google Scholar61https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVWqsbvN&md5=9623598270f25b5bb503a8996cefefd1Plasmon resonance of silver nanoparticles as a method of increasing their antibacterial actionVasil'kov, Alexander Yu.; Dovnar, Ruslan I.; Smotryn, Siarhei M.; Iaskevich, Nikolai N.; Naumkin, Alexander V.Antibiotics (Basel, Switzerland) (2018), 7 (3), 80CODEN: ABSNC4; ISSN:2079-6382. (MDPI AG)In this article, a series of silver-contg. dressings are prepd. by metal-vapor synthesis (MVS), and their antibacterial properties are investigated. The antibacterial activity of the dressings contg. silver nanoparticles (AgNPs) against some Gram-pos., and Gram-neg. microorganisms (Staphylococcus aureus, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Moraxella spp.) has been detd. Based on the plasmon resonance frequency of these nanoparticles, the frequency of laser irradn. of the dressing was chosen. The gauze bandage examd. showed pronounced antibacterial properties, esp. to Staphylococcus aureus strain. When 470 nm laser radiation, with a power of 5 mW, was applied for 5 min, 4 h after inoculating the Petri dish, and placing a bandage contg. silver nanoparticles on it, the antibacterial effect of the latter significantly increased-both against Gram-pos. and Gram-neg. microorganisms. The structure and chem. compn. of the silver-contg. nanocomposite were studied by transmission electron microscopy (TEM), XPS and extended X-ray absorption fine structure (EXAFS). The synthesized AgNPs demonstrate narrow and monomodal particle size distribution with an av. size of 1.75 nm. Atoms of metal in Ag/bandage system are mainly in Ag0 state, and the oxidized atoms are in the form of Ag-Ag-O groups.
- 62Guan, W.; Ji, F.; Xie, Z.; Li, R.; Mei, N. Preparation and photocatalytic performance of nano-TiO2 codoped with iron III and lanthanum III. J. Nanomater. 2015, 2015, 1– 13, DOI: 10.1155/2015/869821Google ScholarThere is no corresponding record for this reference.
- 63Dal’Toé, A. T.; Colpani, G. L.; Padoin, N.; Fiori, M. A.; Soares, C. Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV–visible light. Appl. Surf. Sci. 2018, 441, 1057– 1071, DOI: 10.1016/j.apsusc.2018.01.291Google Scholar63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtlagurw%253D&md5=1b994d85c6486f96b23b8abb52cb547bLanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible lightDal'Toe, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Marcio Antonio; Soares, CintiaApplied Surface Science (2018), 441 (), 1057-1071CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepd. using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization anal. revealed that La doping slightly changed the cryst. phase of TiO2, increased the amt. of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plasmon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amt. of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addn., Ag-La possibly decreased the semiconductor surface energy, which acted pos. in the redn. of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradn. compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradn. was proposed.
- 64Guo, J.; Cai, X.; Li, Y.; Zhai, R.; Zhou, S.; Na, P. The preparation and characterization of a three-dimensional titanium dioxide nanostructure with high surface hydroxyl group density and high performance in water treatment. Chem. Eng. J. 2013, 221, 342– 352, DOI: 10.1016/j.cej.2013.02.005Google Scholar64https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXlsFCjsLk%253D&md5=3d28f1bf8a6daf778c6e3b904f04e14dThe preparation and characterization of a three-dimensional titanium dioxide nanostructure with high surface hydroxyl group density and high performance in water treatmentGuo, Jingwei; Cai, Xiaojiao; Li, Yuan; Zhai, Ruiguo; Zhou, Shimin; Na, PingChemical Engineering Journal (Amsterdam, Netherlands) (2013), 221 (), 342-352CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)A 3D TiO2 nanostructure consisting of a nanoparticle core and needle-like surface was fabricated. The effects of Ti4+ concn., stirring methods and stirring time for TiO2 prepn. were discussed with results from transmission and SEM; meanwhile, the TiO2 growth mechanism was illustrated by morphol. evolution and crystn. of TiO2 spheres. The spherical diam. could be easily controlled by altering the concn. of precursor using a mech. stirring method. XPS, Fourier transform IR spectrometry and thermogravimetric anal. were used to confirm the compn. of TiO2 spheres rich with hydroxyl groups. The product showed excellent ability for As(V) and Cr(VI) removal and could be sepd. using sedimentation. Most of the ions could be removed in less than 1 h, and TiO2 had max. adsorption capacities of 59.7 mg g-1 for As(V) and 21.92 mg g-1 for Cr(VI). The high performance of self-assembled 3D TiO2 in water treatment was due to (1) its large hydroxyl group d. and high sp. surface area and (2) its 3D nanostructure consisting of a nanoparticle core and needle-like surface.
- 65Wang, B.; Zhang, G.; Sun, Z.; Zheng, S.; Frost, R. L. A comparative study about the influence of metal ions (Ce, La and V) doping on the solar-light-induced photodegradation toward rhodamine B. J. Environ. Chem. Eng. 2015, 3, 1444– 1451, DOI: 10.1016/j.jece.2015.05.007Google Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXos1emu7w%253D&md5=b29546f65ab78a7e7740c81ecce1513cA comparative study about the influence of metal ions (Ce, La and V) doping on the solar-light-induced photodegradation toward rhodamine BWang, Bin; Zhang, Guangxin; Sun, Zhiming; Zheng, Shuilin; Frost, Ray L.Journal of Environmental Chemical Engineering (2015), 3 (3), 1444-1451CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)Water contamination by the textile dye effluents has become a serious environmental issue, which are threatening to the human health and biol. diversity. The TiO2 photocatalysis has been proven to be used to remove textile dyes in water. In order to improve its solar-light activity, three metal ions, including cerium (Ce), lanthanum (La) and vanadium (V), were selected as dopants to prep. metal ions doped TiO2 particles by sol-gel method. The synthesized particles were characterized by X-ray diffraction, field SEM, UV-vis diffuse reflectance spectroscopy and XPS. Through the physicochem. properties of the resulting metal ions doped TiO2 particles, we found that characteristics of dopants could strongly affect the cryst. phase and crystallite size, the optical absorption spectrum and the bandgap energy of the modified TiO2 catalysts, and consequently influence the photocatalytic ability. We investigated the link between dopant's characteristics and photoactivity of the doped catalysts, and deduced that the existence of dopant in the modified catalysts is crucial. In the case of Ce or La doping, the dopants homogeneously dispersed on the surface of TiO2 particles as oxides and interacted with TiO2 particles via RE-O-Ti bond. Nevertheless, the V species successfully entered the TiO2 lattice and substituted for Ti4+ due to its similar ionic radius with Ti. The photocatalytic activities of Ce-, La-, or V-doped TiO2 photocatalysts were evaluated by the degrdn. of rhodamine B under simulated solar-light illumination. In our case, only the doping of Ce or V could drive efficient solar-light activity. The bandgap energy of 1.0%-Ce-TiO2 was narrowed to 2.70 eV and the removal ratio for dye could raise up to 83% with a relatively high calcination temp.
- 66Lei, X.; Chen, C.; Li, X.; Xue, X.; Yang, H. Characterization and photocatalytic performance of La and C co-doped anatase TiO2 for photocatalytic reduction of Cr (VI). Sep. Purif. Technol. 2016, 161, 8– 15, DOI: 10.1016/j.seppur.2016.01.030Google Scholar66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1Oisb0%253D&md5=051bc6c9e66db5fcd51b6c6d2e98e1c9Characterization and photocatalytic performance of La and C co-doped anatase TiO2 for photocatalytic reduction of Cr(VI)Lei, X. F.; Chen, C.; Li, X.; Xue, X. X.; Yang, H.Separation and Purification Technology (2016), 161 (), 8-15CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)The La and C co-doped anatase TiO2 nano-materials were synthesized by a hydrothermal method. The structures of La and C co-doped TiO2 were characterized by XRD, FT-IR, XPS, DRS, SEM and nitrogen adsorption-desorption isotherms. The results indicated that pH values have a greater effect on the cryst. phase, crystal size and crystallinity degree of TiO2. The La and C co-doping could inhibit the phase transformation and crystallite growth of TiO2. The photocatalytic activities of La and C co-doped TiO2 for photocatalytic redn. of Cr(VI) under visible light irradn. using different La contents were also studied. The La and C co-doped TiO2 nano-materials with La:Ti wt. ratio of 0.3 exhibits the highest photocatalytic activity for Cr(VI) photocatalytic redn. under visible light irradn., which can be attributed to the synergic effect of the higher BET surface area, surface hydroxyl content and optimum La contents.
- 67Sing, K. S. W. Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure Appl. Chem. 1985, 57, 603– 619, DOI: 10.1351/pac198557040603Google Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXhvFWrtb4%253D&md5=4fbbea83b3a13b5f22e6d26e5d0ab20cReporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984)Sing, K. S. W.; Everett, D. H.; Haul, R. A. W.; Moscou, L.; Pierotti, R. A.; Rouquerol, J.; Siemieniewska, T.Pure and Applied Chemistry (1985), 57 (4), 603-19CODEN: PACHAS; ISSN:0033-4545.Problems and ambiguities in reporting data are discussed. Procedures and terminol. for reporting data re recommended.
- 68Raj, K. J. S.; Viswanathan, B. Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutile. Indian J. Chem., Sect. A: Inorg., Phys., Theor. Anal. 2009, 48, 1378– 1382Google Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFWhtL%252FJ&md5=a0d2e7bf56e9b60ccd4cf75000cc5820Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutileRaj, K. Joseph Antony; Viswanathan, B.Indian Journal of Chemistry, Section A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical Chemistry (2009), 48A (10), 1378-1382CODEN: ICACEC; ISSN:0376-4710. (National Institute of Science Communication and Information Resources)The effect of calcination on P25 TiO2 at different temps. was studied by XRD, N adsorption-desorption isotherm, BET-surface area, pore vol., pore size, particle size and crystallite size to understand the conversion of anatase phase to rutile phase. The fraction of anatase and rutile was detd. using XRD. Although the crystallinity remains the same, the phase change of anatase to rutile is inevitable with temp. The isotherms show the nonporous characteristics of the P25 samples. In addn., nitrogen adsorption by the samples decreased appreciably with crystallinity. The pore vol. and BET surface area show a large decrease at 900°. The particle size, crystallite size, and pore size show an increasing trend with increase in temp. Anal. of the phys. characteristics indicates that P25 titania samples can be used for catalytic applications at <500°.
- 69Deiana, C.; Fois, E.; Coluccia, S.; Martra, G. Surface Structure of TiO2 P25 Nanoparticles: Infrared Study of Hydroxy Groups on Coordinative Defect Sites. J. Phys. Chem. C 2010, 114, 21531– 21538, DOI: 10.1021/jp107671kGoogle Scholar69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsVGksLbO&md5=3d10104e2f98bf7d9f1abe6745cea0d3Surface Structure of TiO2 P25 Nanoparticles: Infrared Study of Hydroxy Groups on Coordinative Defect SitesDeiana, Chiara; Fois, Ettore; Coluccia, Salvatore; Martra, GianmarioJournal of Physical Chemistry C (2010), 114 (49), 21531-21538CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Surface hydroxy groups are known to play a significant role in the photocatalytic behavior of TiO2. The mol. or dissociative character of H2O adsorption on titania is strongly affected by the local surface structure, but dissocn., producing -OH, should prevail on surface sites with a high degree of coordinative unsatn. Here we report an IR investigation of hydroxy groups on low coordination sites of TiO2 P25 (Degussa), a com. titania powder considered a staple in the field of heterogeneous photocatalysis. The presence of coordinatively defective surface terminations well agrees with the roughness of the border of TiO2 particles obsd. by high resoln. transmission electron microscopy. Furthermore, IR spectra of adsorbed CO were used to probe the Lewis acidity of surface Ti4+ ions exposed after the removal of water mols. and hydroxy groups. Evidence for two addnl. types of surface cationic sites with respect those reported in the literature was found.
- 70Bendahou, K.; Cherif, L.; Siffert, S.; Tidahy, H.; Benaissa, H.; Aboukais, A. The effect of the use of lanthanum-doped mesoporous SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts for total oxidation of toluene. Appl. Catal., A 2008, 351, 82– 87, DOI: 10.1016/j.apcata.2008.09.001Google Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlWkur%252FK&md5=ad48d3824a0055cc5149306e89fa2e3bThe effect of the use of lanthanum-doped mesoporous SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts for total oxidation of tolueneBendahou, K.; Cherif, L.; Siffert, S.; Tidahy, H. L.; Benaissa, H.; Aboukais, A.Applied Catalysis, A: General (2008), 351 (1), 82-87CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Platinum and palladium were supported on a mesoporous SBA-15 for total oxidn. of toluene. The effects of the use of lanthanum-doped SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts and on the total oxidn. of toluene were evaluated. Lanthanum-substituted mesoporous SBA-15 mol. sieve was prepd. by direct synthesis and post-synthesis procedures using lanthanum nitrate as source. By post-synthesis procedure, La was ion-exchanged on calcined silica. Characterizations by at. absorption, x-ray diffraction, nitrogen adsorption, 29Si MAS NMR and FT-IR spectroscopy were carried out to evaluate the efficiency of the incorporation of lanthanum by these procedures. Lanthanum was well incorporated into the SBA-15 structure only by post-synthesis procedure. Structural and textural evolutions of LaSBA-PS (post-synthesis) material were studied according to the Si/La ratio. These LaSBA-15 mesoporous mol. sieves retain the hexagonal order and phys. properties of siliceous SBA-15 material. After removing the surfactant mols. by calcinations, 1% of platinum or 0.5% of palladium was impregnated on SBA-15 or LaSBA-PS (Si/La = 20) via incipient wetness technique using resp. hexachloroplatinic acid and palladium nitrate as the Pt and Pd sources. The activity for toluene total oxidn. of the pre-reduced samples follows this order: 0.5% Pd/SBA-15 > 1% Pt/SBA-15 > 0.5% Pd/LaSBA-PS > 1% Pt/LaSBA-PS. 0.5% Pd/SBA-15 was a interesting catalyst for VOC oxidn. However, the lower activity of the lanthanum catalysts could be explained by patches of LaOX residing on the surface of the metal particles (particularly on Pd) and/or to the interaction between the metal and LaSBA-PS which modifies the electron d. of the metal. For the Pt-based catalyst the obsd. higher dispersion of platinum species for Pt/LaSBA-PS and thus to the increase of the Pt-O bond strength with the decrease of the Pt crystallite size could also inhibit the reaction.
- 71Dai, K.; Peng, T.; Chen, H.; Liu, J.; Zan, L. Photocatalytic degradation of commercial phoxim over La-doped TiO2 nanoparticles in aqueous suspension. Environ. Sci. Technol. 2009, 43, 1540– 1545, DOI: 10.1021/es802724qGoogle Scholar71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsl2mug%253D%253D&md5=dfa465b53e9c4f6a4b829475c311c440Photocatalytic degradation of commercial phoxim over lanthanum-doped titanium oxide nanoparticles in aqueous suspensionDai, Ke; Peng, Tianyou; Chen, Hao; Liu, Juan; Zan, LinEnvironmental Science & Technology (2009), 43 (5), 1540-1545CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Photocatalytic degrdn. of com. phoxim emulsion in aq. suspension was investigated by using La-doped mesoporous TiO2 nanoparticles (m-TiO2) as the photocatalyst under UV irradn. Effects of La-doping level, calcination temp., and addnl. amt. of the photocatalyst on the photocatalytic degrdn. efficiency were investigated in detail. Exptl. results indicate that 20 mg L-1 phoxim in 0.5 g L-1 La/m-TiO2 suspension (the initial pH 4.43) can be decompd. as prolonging the irradn. time. Almost 100 % phoxim was decompd. after 4 h irradn. according to the spectrophotometric analyses, whereas the mineralization rate of phoxim just reached ca. 80 % as checked by ion chromatog. (IC) analyses. The elimination of the org. solvent in the phoxim emulsion as well as the formation and decompn. of some degrdn. intermediates were obsd. by high-performance liq. chromatog.-mass spectroscopy (HPLC-MS). On the basis of the anal. results on the photocatalytic degrdn. intermediates, two possible photocatalytic degrdn. pathways are proposed under the present exptl. conditions, which reveal that both the hydrolysis and adsorption of phoxim under UV light irradn. play important roles during the photocatalytic degrdn. of phoxim.
- 72Shi, Z.-l.; Lai, H.; Yao, S.-h.; Wang, S.-f. Preparation, characterization and photocatalytic activity of lanthanum doped mesoporous titanium dioxide. Chin. J. Chem. Phys. 2012, 25, 96, DOI: 10.1088/1674-0068/25/01/96-102Google Scholar72https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XltFSjtrw%253D&md5=ce645aebd6da53264cc757bf17c056cfPreparation, characterization and photocatalytic activity of lanthanum doped mesoporous titanium dioxideShi, Zhong-liang; Lai, Hong; Yao, Shu-hua; Wang, Shao-fengChinese Journal of Chemical Physics (2012), 25 (1), 96-102CODEN: CJCPA6; ISSN:1674-0068. (Chinese Physical Society)La doped mesoporous TiO2 photocatalysts with different La content were synthesized by template method using tetra-Bu titanate (Ti(OBu)4) as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric DTA, N2 adsorption-desorption measurements, x-ray diffraction, and UV-visible absorption spectroscopy. The effect of La3+ doping concn. from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was studied. The characterizations indicated that the photocatalysts possessed a homogeneous pore diam. of ∼10 nm with high surface area of 165 m2/g. XPS measurements indicated the presence of C in the doped samples in addn. to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecompn. showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradn.
- 73Wang, J.; Tafen, D. N.; Lewis, J. P.; Hong, Z.; Manivannan, A.; Zhi, M.; Li, M.; Wu, N. Origin of photocatalytic activity of nitrogen-doped TiO2 nanobelts. J. Am. Chem. Soc. 2009, 131, 12290– 12297, DOI: 10.1021/ja903781hGoogle Scholar73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsFyis7w%253D&md5=f508306db56e92c53ae6d77de52eb089Origin of Photocatalytic Activity of Nitrogen-Doped TiO2 NanobeltsWang, Jin; Tafen, De Nyago; Lewis, James P.; Hong, Zhanglian; Manivannan, Ayyakkannu; Zhi, Mingjia; Li, Ming; Wu, NianqiangJournal of the American Chemical Society (2009), 131 (34), 12290-12297CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Expts. combined with the d. functional theory (DFT) calcn. have been performed to understand the underlying photocatalysis mechanism of the nitrogen-doped titania nanobelts. Nitrogen-doped anatase titania nanobelts are prepd. via hydrothermal processing and subsequent heat treatment in NH3. Both the nitrogen content and the oxygen vacancy concn. increase with increasing the NH3 treatment temp. Nitrogen doping leads to an add-on shoulder on the edge of the valence band, the localized N 2p levels above the valence band max., and the 3d states of Ti3+ below the conduction band, which is confirmed by DFT calcn. and XPS measurement. Extension of the light absorption from the UV region to the visible-light region arises from the N 2p levels near the valence band and from the color centers induced by the oxygen vacancies and the Ti3+ species. Nitrogen doping allows visible-light-responsive photocatalytic activity but lowers UV-light-responsive photocatalytic activity. The visible-light photocatalytic activity originates from the N 2p levels near the valence band. The oxygen vacancies and the assocd. Ti3+ species act as the recombination centers for the photoinduced electrons and holes. They reduce the photocatalytic activity although they contribute to the visible light absorbance.
- 74Kumar, M. P.; Jagannathan, R.; Ravichandran, S. Photoelectrochemical system for unassisted high-efficiency water-splitting reactions using N-doped TiO2 nanotubes. Energy Fuels 2020, 34, 9030– 9036, DOI: 10.1021/acs.energyfuels.0c00634Google Scholar74https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVWisrfP&md5=99d4ee35bf9320db5dffabac09eeb71ePhotoelectrochemical System for Unassisted High-Efficiency Water-Splitting Reactions Using N-Doped TiO2 NanotubesKumar, M. Praveen; Jagannathan, R.; Ravichandran, S.Energy & Fuels (2020), 34 (7), 9030-9036CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)In this study, we report a facile one-step synthesis of porous and defect-rich nitrogen (N)-doped TiO2 nanotubes by the electrochem. anodization process with in situ N-doping on TiO2 nanotubes using nitrogen gas as a nitrogen source. N-doped TiO2 exhibits enhanced visible-light photocatalytic activity toward the photoelectrochem. water-splitting reaction and high stability due to nitrogen doping and band-gap narrowing. Nitrogen-doped nanotubes exhibit unique and efficient photoelectrochem. cell (PEC) water-splitting activity for H2 generation in aq. electrolytes with a pH gradient. The nitrogen doping and the concurrent defects increase the charge d., which can effectively tune the band gap toward the visible light region, hindering the electron-hole recombination process compared to that in bare TiO2 nanotubes. The PEC has been assembled with chem. (pH) bias (unassisted) by the imposition of electrolytes of different pH's, resulting in a pH gradient between the photoanode and the metal cathode. The pH-biased photoelectrochem. cell has been constructed with 1 M NaOH on the photoanode side and 1 M H2SO4 on the cathode side. The PEC of N-doped TiO2 nanotubes exhibits an open circuit potential of 1.3 V with a photocurrent d. of 0.76 mA/cm2 (at 0.5 V) and solar-to-hydrogen (STH) efficiency of 0.5% in an outdoor sunlight measurement. The photoelectrode exhibits a long-term stability of 120 h in an outdoor measurement.
- 75Asahi, R.; Morikawa, T.; Ohwaki, T.; Aoki, K.; Taga, Y. Visible-light photocatalysis in nitrogen-doped titanium oxides. Science 2001, 293, 269– 271, DOI: 10.1126/science.1061051Google Scholar75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXlt1yitbc%253D&md5=db2b823b547b5c3bb17ab314d215660aVisible-light photocatalysis in nitrogen-doped titanium oxidesAsahi, R.; Morikawa, T.; Ohwaki, T.; Aoki, K.; Taga, Y.Science (Washington, DC, United States) (2001), 293 (5528), 269-271CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)To use solar irradn. or interior lighting efficiently, the authors sought a photocatalyst with high reactivity under visible tight. Films and powders of TiO2-xNx have revealed an improvement over titanium dioxide (TiO2) under visible light (wavelength < 500 nm) in optical absorption and photocatalytic activity such as photodegrdns. of Methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface. Nitrogen doped into substitutional sites of TiO2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calcns. and x-ray photoemission spectroscopy.
- 76Gomes, J.; Lincho, J.; Domingues, E.; Quinta-Ferreira, R. M.; Martins, R. C. N–TiO2 photocatalysts: A review of their characteristics and capacity for emerging contaminants removal. Water 2019, 11, 373, DOI: 10.3390/w11020373Google Scholar76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitlelsr3M&md5=f661aae2427a893eb11183f89942a2bdN-TiO2 photocatalysts: a review of their characteristics and capacity for emerging contaminants removalGomes, Joao; Lincho, Joao; Domingues, Eva; Quinta-Ferreidra, Rosa M.; Martins, Rui C.Water (Basel, Switzerland) (2019), 11 (2), 373CODEN: WATEGH; ISSN:2073-4441. (MDPI AG)Titanium dioxide is the most used photocatalyst in wastewater treatment; its semiconductor capacity allows the indirect prodn. of reactive oxidative species. The main drawback of the application of TiO2 is related to its high band-gap energy. The nonmetal that is most often used as the doping element is nitrogen, which is due to its capacity to reduce the band-gap energy at low prepn. costs. There are multiple and assorted methods of prepn. The main advantages and disadvantages of a wide range of prepn. methods were discussed in this paper. Different sources of N were also analyzed, and their individual impact on the characteristics of N-TiO2 was assessed. The core of this paper was focused on the large spectrum of anal. techniques to detect modifications in the TiO2 structure from the incorporation of N. The effect of N-TiO2 co-doping was also analyzed, as well as the main characteristics that are relevant to the performance of the catalyst, such as its particle size, surface area, quantum size effect, cryst. phases, and the hydrophilicity of the catalyst surface. Powder is the most used form of N-TiO2, but the economic benefits and applications involving continuous reactors were also analyzed with supported N-TiO2. Moreover, the degrdn. of contaminants emerging from water and wastewater using N-TiO2 and co-doped TiO2 was also discussed.
- 77Zaleska, A. Doped-TiO2: a review. Recent Pat. Eng. 2008, 2, 157– 164, DOI: 10.2174/187221208786306289Google Scholar77https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVaqtrjI&md5=f58bc711feafe750f04a9c2e15c59801Doped-TiO2: a reviewZaleska, AdrianaRecent Patents on Engineering (2008), 2 (3), 157-164CODEN: RPEEBL; ISSN:1872-2121. (Bentham Science Publishers Ltd.)A review. Titanium dioxide represents an effective photocatalyst for water and air purifn. and for self-cleaning surfaces. Addnl., it can be used as antibacterial agent because of strong oxidn. activity and superhydrophilicity. TiO2 shows relatively high reactivity and chem. stability under UV light (λ < 387 nm), whose energy exceeds the band gap of 3.3 eV in the anatase cryst. phase. The development of photocatalysts exhibiting high reactivity under visible light (λ > 400 nm) should allow the main part of the solar spectrum, even under poor illumination of interior lighting, to be used. Visible light-activated TiO2 could be prepd. by metal-ion implantation, reducing of TiO2, nonmetal doping or sensitizing of TiO2 with dyes. This paper reviews prepn. methods of doped-TiO2 with metallic and nonmetallic species, including various types of dopants and doping methods currently available. The mechanism of heterogeneous photocatalysis in the presence of TiO2 is also discussed.
- 78Matthews, R. W.; Abdullah, M.; Low, G. K. C. Photocatalytic oxidation for total organic carbon analysis. Anal. Chim. Acta 1990, 233, 171– 179, DOI: 10.1016/S0003-2670(00)83476-5Google Scholar78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3cXlt1Smsbg%253D&md5=567a97f0edc6277ebac745b56d229bfePhotocatalytic oxidation for total organic carbon analysisMatthews, R. W.; Abdullah, M.; Low, G. K. C.Analytica Chimica Acta (1990), 233 (2), 171-9CODEN: ACACAM; ISSN:0003-2670.A method and app. for the detn. of org. C in water are described. Photocatalytic oxidn. of org. matter by near-UV illuminated TiO2 is used to convert org. C to CO2. Atm. O is the oxidant. The the light source is a 20-W black-light fluorescent tube. The CO2 equilibrates between the reaction loop and a cond. detection loop and the recirculated air forms the interface between the 2 loops. The method is suitable for anal. of water contg. 0.1-30 μg/mL org. C and sample vols. of 1-40 mL. Higher concns. can be detd. after appropriate diln. Times for 99% oxidn. of org. solutes to CO2 are ≤10 min..
- 79Liu, Y.; Xie, L.; Li, Y.; Qu, J.; Zheng, J.; Li, X. Photocatalytic Hydrogen Generation Over Lanthanum Doped TiO2 Under UV Light Irradiation. J. Nanosci. Nanotechnol. 2009, 9, 1514– 1517, DOI: 10.1166/jnn.2009.C191Google Scholar79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXjslSgs7o%253D&md5=685377812ab1e101ef6a13694c0cdb07Photocatalytic hydrogen generation over lanthanum doped TiO2 under UV light irradiationLiu, Y.; Xie, L.; Li, Y.; Qu, J. L.; Zheng, J.; Li, X. G.Journal of Nanoscience and Nanotechnology (2009), 9 (2), 1514-1517CODEN: JNNOAR; ISSN:1533-4880. (American Scientific Publishers)TiO2 nanoparticles doped with different amt. of lanthanum were obtained by sol-gel approach and followed annealing at different temp. The crystal size of TiO2 doped with lanthanum was smaller than that of pure TiO2. Photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 was investigated. The photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 is higher than that of pure TiO2. It was found that the optimal photocatalyst was TiO2 doped with 2 wt% lanthanum and calcined at 600 °C for 4 h which had hydrogen generation rate 700.6 μmol h-1.
- 80Zhao, Y.; Wang, W.; He, L. The effects of Co/N dopants on the electronic, redox potential, optical, and photocatalytic water-splitting properties of TiO2: First principles calculations. Chem. Phys. Lett. 2017, 685, 108– 113, DOI: 10.1016/j.cplett.2017.07.046Google Scholar80https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXht1CksLvK&md5=318eea5e2bacd156207e71d4ea6220b6The effects of Co/N dopants on the electronic, redox potential, optical, and photocatalytic water-splitting properties of TiO2: First principles calculationsZhao, Yafei; Wang, Wei; He, LiangChemical Physics Letters (2017), 685 (), 108-113CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)The crystal structure, formation energy, electronic and optical properties of undoped, Co, N doped and co-doped TiO2 were investigated by first principles calcns. Considering the potential of water redox reaction of these systems indicate that only N-, Co-1N- and Co-2N co-doped TiO2 meet the requirement of the photosplitting water. Moreover, the optical absorption threshold and absorption area of Co-2N co-doped TiO2 are obviously enlarged compared with the undoped TiO2. Co-2N co-doped TiO2 has the highest light absorption efficiency and hydrogen prodn. efficiency, due to the presence of curved and broad impurity levels that greatly improve the carriers' mobility and sepn.
- 81Eidsvåg, H.; Bentouba, S.; Vajeeston, P.; Yohi, S.; Velauthapillai, D. TiO2 as a Photocatalyst for Water Splitting─An Experimental and Theoretical Review. Molecules 2021, 26, 1687, DOI: 10.3390/molecules26061687Google ScholarThere is no corresponding record for this reference.
- 82Shwetharani, R.; Sakar, M.; Chandan, H.; Balakrishna, R. G. Observation of simultaneous photocatalytic degradation and hydrogen evolution on the lanthanum modified TiO2 nanostructures. Mater. Lett. 2018, 218, 262– 265, DOI: 10.1016/j.matlet.2018.02.031Google Scholar82https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXis1arurs%253D&md5=2398a6b043619667ea9fb93078a17afbObservation of simultaneous photocatalytic degradation and hydrogen evolution on the lanthanum modified TiO2 nanostructuresShwetharani, R.; Sakar, M.; Chandan, H. R.; Geetha Balakrishna, R.Materials Letters (2018), 218 (), 262-265CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The simultaneous photocatalytic degrdn. of dye-polluted water and hydrogen prodn. has been demonstrated on the lanthanum-modified TiO2 (La-TiO2) nanostructures. The obsd. changes in the X-ray diffraction pattern of La-TiO2 with respect to pristine-TiO2 indicated the incorporation of La into the lattices of TiO2. The surface adsorption anal. and electron microscopy images revealed the enhanced surface area with spherical and rod-like morphol. for TiO2 and La-TiO2 resp. The obsd. red-shift in the absorption spectrum and the estd. band-gap energy indicated that the La-doping sufficiently altered the band-structure of TiO2 to absorb visible light. The calcd. band-edge positions revealed that La doping suitably altered the band-edge potential of TiO2 for the simultaneous degrdn. and hydrogen prodn.
- 83Choi, H.; Khan, S.; Choi, J.; Dinh, D. T. T.; Lee, S. Y.; Paik, U.; Cho, S.-H.; Kim, S. Synergetic control of band gap and structural transformation for optimizing TiO2 photocatalysts. Appl. Catal., B 2017, 210, 513– 521, DOI: 10.1016/j.apcatb.2017.04.020Google Scholar83https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmtV2mu74%253D&md5=209834443a5e3288587889c8ba9fd416Synergetic control of band gap and structural transformation for optimizing TiO2 photocatalystsChoi, Heechae; Khan, Sovann; Choi, Junghyun; Dinh, Duong T. T.; Lee, Seung Yong; Paik, Ungyu; Cho, So-Hye; Kim, SeungchulApplied Catalysis, B: Environmental (2017), 210 (), 513-521CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)Impurity doping and synthesizing polymorphic particles are the common strategies to improve activity of TiO2 photocatalyst by lowering the band gap and enhancing electron-hole sepn. rate. However, these two approaches have side effects. Doping of impurities make space charge region (SCR) thinner near the surface, which requires smaller sized particles than undoped TiO2 for the optimal performance. Polymorphic TiO2 particles, in which rutile and anatase phases coexist in a particle, are usually large due to energetic unstability of the rutile phase in a fine particle. For this contradiction that one needs small size while the other needs large size, two effects are not easy to be combined. In this study, we suggest a dual-doping strategy to solve the contradictory problem of SCR redn. by donor doping and inevitable size growth in polymorphic particles. We successfully dope W, a band gap narrower, into fine size of polymorphic particles by Sn-codoping, a promoter of the anatase-to-rutile transformation (ART), and demonstrate greatly improved photocatalytic activity. The accelerated ART by Sn-doping could keep the size of polymorph junctioned TiO2 small (∼10 nm) as lower temp. annealing become able to induce the ART. The concept of dual doping with a band gap narrower and an ART promoter provides a way to synthesize highly active photocatalysts by overcoming the drawback from shortened SCR length.
- 84Singh, B.; Mehta, B. R. Relationship between nature of metal-oxide contacts and resistive switching properties of copper oxide thin film based devices. Thin Solid Films 2014, 569, 35– 43, DOI: 10.1016/j.tsf.2014.08.030Google Scholar84https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVOhtbbN&md5=aa46ba56eeff840f31b7658521fd3bf8Relationship between nature of metal-oxide contacts and resistive switching properties of copper oxide thin film based devicesSingh, Bharti; Mehta, B. R.Thin Solid Films (2014), 569 (), 35-43CODEN: THSFAP; ISSN:0040-6090. (Elsevier B.V.)The current-voltage and resistive switching properties of Cu2O and CuO based resistive random access memories in metal-oxide-metal structure with Cu as bottom electrode and different metals (Ti, Ag, Au and Pd) as top electrodes were studied. The observation of resistive switching in Cu2O and its absence in CuO based devices indicates that ohmic nature of top and bottom metal-oxide contacts is favorable for resistive switching behavior. The rectifying metal-oxide contact results in the applied voltage drop at the rectifying contact, resulting in the absence of elec. field induced structural changes which are crucial for occurrence of resistive switching. The values of switching parameters, such as, electroforming, reset, set voltages and also the resistance ratio also depend upon the work function of the electrode materials and nature of metal-oxide interface.
- 85Grätzel, M. Photoelectrochemical cells. Nature 2001, 414, 338– 344, DOI: 10.1038/35104607Google Scholar85https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXovFGitr8%253D&md5=2b0390f22ab99b07caec95b79454a7ebPhotoelectrochemical cellsGratzel, MichaelNature (London, United Kingdom) (2001), 414 (6861), 338-344CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)A review discussing the historical background, and present status and development prospects of new generation of photoelectrochem. cells.
- 86Malik, A. S.; Liu, T.; Dupuis, M.; Li, R.; Li, C. Water Oxidation on TiO2: A Comparative DFT Study of 1e–, 2e–, and 4e– Processes on Rutile, Anatase, and Brookite. J. Phys. Chem. C 2020, 124, 8094– 8100, DOI: 10.1021/acs.jpcc.9b11450Google Scholar86https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXls12iurg%253D&md5=44265f2bc2e38bc6087f3a4d25e64cd6Water oxidation on TiO2: a comparative DFT study of 1e-, 2e-, and 4e- processes on rutile, anatase, and brookiteMalik, Anum Shahid; Liu, Taifeng; Dupuis, Michel; Li, Rengui; Li, CanJournal of Physical Chemistry C (2020), 124 (15), 8094-8100CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Exptl. studies of the surface reactions of photocatalyzed or photoelectrocatalyzed water oxidn. on rutile, anatase, and brookite TiO2 show significant differences between the three polymorphs. Yet a fundamental understanding of the differences is still lacking. In this work, we carried out a systematic comparative d. functional theory (DFT) investigation of the mechanisms and energetics of water oxidn. on rutile TiO2 (110), anatase TiO2 (101), and brookite TiO2 (210) model surfaces. Our results indicate that for all three phases, the most facile mechanism of water oxidn. proceeds as a two-electron/proton process toward H2O2 formation via surface peroxo O* intermediates. The calcd. overall overpotentials toward H2O2 formation are ~ 0.27, 0.51, and 0.62 V on rutile, anatase, and brookite, resp. The rate-limiting steps toward H2O2 formation are the OH* formation step for all three phases. We studied also the effect of pH. pH alters the binding energies of the reaction intermediates and affects the threshold values for the 1-electron, 2-electron, and 4-electron processes but does not affect the selectivity. Overpotentials for the 4-electron O2 evolution range from 0.8, 1.04, and ~ 1.15 V on rutile, anatase, and brookite, resp., with the same rate-detg. steps as for the 2-electron process. Under photocatalytic conditions of light irradn. corresponding to the redox potential vs. NHE of photogenerated holes in the valence band of the materials (~ 3.0 V for rutile, ~ 3.2 V for anatase, and ~ 3.3 V for brookite), there is enough energy to drive the 4-electron O2 evolution spontaneously as well. Under these conditions, product selectivity (H2O2 vs O2) may require characterizing the reaction kinetics rather than coming out from the thermodn. overpotentials.
- 87Valdés, Á.; Qu, Z. W.; Kroes, G. J.; Rossmeisl, J.; Nørskov, J. K. Oxidation and Photo-Oxidation of Water on TiO2 Surface. J. Phys. Chem. C 2008, 112, 9872– 9879, DOI: 10.1021/jp711929dGoogle Scholar87https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXmvFOru7w%253D&md5=f27936ce0890b213c057ddcfd8ee382eOxidation and Photo-Oxidation of Water on TiO2 SurfaceValdes, A.; Qu, Z.-W.; Kroes, G.-J.; Rossmeisl, J.; Norskov, J. K.Journal of Physical Chemistry C (2008), 112 (26), 9872-9879CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The oxidn. and photo-oxidn. of water on the rutile TiO2(110) surface is investigated using d. functional theory (DFT) calcns. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed for the electrolysis and photoelectrolysis of water. We found that the most difficult step in the splitting of water process is the reaction of a H2O mol. with a vacancy in the surface to form an adsorbed hydroxyl group (OH*). Comparison to expt. shows that the computed overpotential for O2 evolution (0.78 V) is available under the exptl. conditions required for both oxygen and hydrogen evolution.
- 88Jallouli, N.; Elghniji, K.; Trabelsi, H.; Ksibi, M. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation. Arabian J. Chem. 2017, 10, S3640– S3645, DOI: 10.1016/j.arabjc.2014.03.014Google Scholar88https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntlartLc%253D&md5=19fdfd22483a77a9fb46b2af91af3528Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiationJallouli, Nabil; Elghniji, Kais; Trabelsi, Hassen; Ksibi, MohamedArabian Journal of Chemistry (2017), 10 (Suppl._2), S3640-S3645CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)In the present study, photocatalytic degrdn. of acetaminophen ((N-(4-hydroxyphe-nyl)acetamide)), an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegrdn. of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10-4 M paracetamol was degraded under UV irradn. Changes in pH values affected the adsorption and the photodegrdn. of paracetamol. pH 9.0 is found to be the optimum for the photodegrdn. of paracetamol. HPLC detected hydroquinone, benzoquinone, p-nitrophenol, and 1,2,4-trihydroxybenzene during the TiO2-assisted photodegrdn. of paracetamol among which some pathway products are disclosed for the first time. The results showed that TiO2 suspension/UV system is more efficient than the TiO2/cellulosic fiber mode combined to solar light for the photocatalytic degrdn. of paracetamol. Nerveless the immobilization of TiO2 showed many advantages over slurry system because it can enhance adsorption properties while allowing easy sepn. of the photocatalyst from the treated soln. with improved reusable performance.
- 89López Zavala, M. Á.; Jaber Lara, C. R. Degradation of Paracetamol and Its Oxidation Products in Surface Water by Electrochemical Oxidation. Environ. Eng. Sci. 2018, 35, 1248– 1254, DOI: 10.1089/ees.2018.0023Google Scholar89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVyjur7O&md5=8d94f7d3bf7fbdfc2b4c39f9cd4660e1Degradation of paracetamol and its oxidation products in surface water by electrochemical oxidationLopez Zavala, Miguel Angel; Jaber Lara, Camila ReneeEnvironmental Engineering Science (2018), 35 (11), 1248-1254CODEN: EESCF5; ISSN:1092-8758. (Mary Ann Liebert, Inc.)Paracetamol and its toxic transformation products have been found in surface water, wastewater, and drinking water. Effective methods to degrade these products must be found to reduce their detrimental effects on microorganisms in aquatic systems and minimize the concern on human health. Thus, this study looked into the electrochem. oxidn. of paracetamol and its oxidn. products on surface water, and results were compared with those of paracetamol synthetic soln. oxidn. Degrdn. of paracetamol was conducted using a stainless steel electrode cell, a pH of 3, and d.c. densities of 5.7 mA/cm2 (6 V) and 7.6 mA/cm2 (12 V). For both current densities applied, the pharmaceutical and its oxidn. products obsd. by high-performance liq. chromatog. with diode-array detection (HPLC-DAD) at 254 nm were totally degraded. Faster degrdn. of paracetamol was obsd. at a higher c.d. Indeed, 95% of paracetamol was oxidized in only 15 min at the 7.6 mA/cm2 c.d. In comparison to the paracetamol synthetic soln.'s oxidn., degrdn. of paracetamol was faster in the surface water than the synthetic soln., at 5.7 mA/cm2. Nevertheless, at 7.6 mA/cm2, total degrdn. of paracetamol in surface water was delayed up to 40 min, vs. 7.5 min in the synthetic soln. Three oxidn. products, obsd. by HPLC-DAD at 254 nm, were fully oxidized. In comparison with the paracetamol synthetic soln., degrdn. of the oxidn. products in surface water was faster than in synthetic solns. for both current densities. Furthermore, the 7.6 mA/cm2 c.d. resulted in faster degrdn. of oxidn. products. Results obtained from this work are promising for practical applications because short reaction times and low current densities are needed for degrdn. of paracetamol and its oxidn. products. These densities can be potentially supplied by photovoltaic cells.
- 90Moctezuma, E.; Leyva, E.; Aguilar, C. A.; Luna, R. A.; Montalvo, C. Photocatalytic degradation of paracetamol: Intermediates and total reaction mechanism. J. Hazard. Mater. 2012, 243, 130– 138, DOI: 10.1016/j.jhazmat.2012.10.010Google Scholar90https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsF2ru7%252FI&md5=54ac0825972b5fd36fc01e3f7c3aa727Photocatalytic degradation of paracetamol: Intermediates and total reaction mechanismMoctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A.; Luna, Raul A.; Montalvo, CarlosJournal of Hazardous Materials (2012), 243 (), 130-138CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)The advanced oxidn. of paracetamol (PAM) promoted by TiO2/UV system in aq. medium was studied. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidn. of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixts. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the arom. amide present in PAM and subsequent formation of several arom. intermediate compds. such as p-aminophenol and p-nitrophenol. These arom. compds. were eventually converted into trans-unsatd. carboxylic acids. Based on these exptl. results, an alternative deacylation mechanism for the photocatalytic oxidn. of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to study oxidative mechanisms of pharmaceuticals.
- 91Xiong, Z.; Ma, J.; Ng, W. J.; Waite, T. D.; Zhao, X. Silver-modified mesoporous TiO2 photocatalyst for water purification. Water Res. 2011, 45, 2095– 2103, DOI: 10.1016/j.watres.2010.12.019Google Scholar91https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXitFaqurg%253D&md5=1337639a5250674d4251a2cb8f8d7b9eSilver-modified mesoporous TiO2 photocatalyst for water purificationXiong, Zhigang; Ma, Jizhen; Ng, Wun Jern; Waite, T. David; Zhao, X. S.Water Research (2011), 45 (5), 2095-2103CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)Mesoporous anatase (TiO2) was modified with silver (Ag) nanoparticles using a photoredn. method. Performance of the resulting TiO2-Ag nanocomposites for water purifn. was evaluated using degrdn. of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli) under UV irradn. The composites with different Ag loadings were characterized using phys. adsorption of nitrogen, X-ray diffraction, XPS and UV-Visible diffuse reflectance spectroscopic techniques. The results showed that metallic Ag nanoparticles were firmly immobilized on the TiO2 surface, which improved electron-hole sepn. by forming the Schottky barrier at the TiO2-Ag interface. Photocatalytic degrdn. of RhB and inactivation of E. coli effectively occurred in an analogical trend. The deposited Ag slightly decreased adsorption of target pollutants, but greatly increased adsorption of mol. oxygen with the latter enhancing prodn. of reactive oxygen species (ROSs) with concomitant increase in contaminant photodegrdn. The optimal Ag loadings for RhB degrdn. and E. coli disinfection were 0.25 wt% and 2.0 wt%, resp. The composite photocatalysts were stable and could be used repeatedly under UV irradn.
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Abstract
Figure 1
Figure 1. X-ray diffraction analysis of pristine and Ag nanoparticle-coated TiO2 powders.
Figure 2
Figure 2. HRTEM images of the Ag (1 wt %) nanoparticle-coated TiO2 powder at different magnification scales (a) 200 nm, (b) 20 nm, and (c) 2 nm.
Figure 3
Figure 3. XPS core spectra of (a) Ti 2p, (b) O 1s, and (c) Ag 3d. The results of panels (a and b) are compared with those of the commercial P25 powder.
Figure 4
Figure 4. Plots of the Kubelka–Munk function versus the energy of the absorbed light for pure and Ag nanoparticle-coated mesoporous TiO2.
Figure 5
Figure 5. Adsorption–desorption isotherms of nitrogen on pristine and Ag nanoparticle-coated mesoporous TiO2 at 77 K.
Figure 6
Figure 6. (a) UV–Visible absorption spectra of paracetamol photodegradation using 1 wt %Ag/TiO2 and (b) paracetamol photocatalytic degradation over pristine and Ag nanoparticles-coated mesoporous TiO2 under natural solar light irradiation. The results were compared with N- and La-doped TiO2 powder samples. (c) Recycling photocatalytic degradation of paracetamol over 1 wt % Ag/TiO2 under natural solar light irradiation.
Figure 7
Figure 7. Photocatalytic H2 production using different photocatalysts measured at 1 sun irradiation. Note that the electrolyte contains paracetamol (10 ppm) and TEOA, a sacrificial agent.
Figure 8
Figure 8. Gibbs free energy graph as a function of the Fermi level of anatase TiO2 (101) for OER at pH 7 under (a) dark and (b) light irradiation conditions.
Figure 9
Figure 9. Gibbs free energy diagrams of (a) TiO2 and (b) Ag@TiO2 under UV light irradiation.
Figure 10
Figure 10. Schematic illustration of (a) energy band diagrams of pristine anatase TiO2 and Ag@TiO2 and (b) the photocatalytic degradation of paracetamol and hydrogen gas evolution on Ag/TiO2 photocatalysts.
References
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- 1Schwarzenbach, R. P.; Egli, T.; Hofstetter, T. B.; von Gunten, U.; Wehrli, B. Global Water Pollution and Human Health. Annu. Rev. Environ. Resour. 2010, 35, 109– 136, DOI: 10.1146/annurev-environ-100809-125342There is no corresponding record for this reference.
- 2Davies, K. R.; Cherif, Y.; Pazhani, G. P.; Anantharaj, S.; Azzi, H.; Terashima, C.; Fujishima, A.; Pitchaimuthu, S. The upsurge of photocatalysts in antibiotic micropollutants treatment: Materials design, recovery, toxicity and bioanalysis. J. Photochem. Photobiol., C 2021, 48, 100437 DOI: 10.1016/j.jphotochemrev.2021.1004372https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsleqsbrE&md5=8e857f580b37c032cb5038062db71bf1The upsurge of photocatalysts in antibiotic micropollutants treatment: Materials design, recovery, toxicity and bioanalysisDavies, Katherine Rebecca; Cherif, Yassine; Pazhani, Gururaja Perumal; Anantharaj, Sengeni; Azzi, Hajer; Terashima, Chiaki; Fujishima, Akira; Pitchaimuthu, SudhagarJournal of Photochemistry and Photobiology, C: Photochemistry Reviews (2021), 48 (), 100437CODEN: JPPCAF; ISSN:1389-5567. (Elsevier B.V.)A review. The excessive use of antimicrobial agents such as antibiotics and disinfectants for domestic purposes and industries polluted the water bodies severely in the recent past. Thus released antimicrobial agents neg. impact the environment and human health as it induce antimicrobial resistance (AMR) to microbes in the environment. Conventional biodegrdn. routes showed feasible antibiotics pollutants degrdn. Nonetheless, they often demand a long time of operation (usually in days) and a major portion of the antimicrobial agents is left untreated unlike the complete oxidn. with advanced oxidn. processes. The residues of antibiotics left in the water bodies accelerate growth of microorganisms (bacterial, fungal, and viral) with AMR. In virtue of avoiding the catastrophe of widespread AMR, photocatalysis assisted antibiotic pollutant treatment is recently gaining a great popularity as an advanced oxidn. process and has shown to be useful for the removal of antimicrobial compds., mainly antibiotics. Recent review reports on photocatalytic antibiotic degrdn. focus on summarizing materials progress and antibiotics pollutants in chronol. viewpoints. However, the relationship between photocatalytic materials and antibiotics oxidn. reaction pathways and the toxicity of byproducts are needed to be shown with better clarity to transfer the photocatalysis technique from lab to market in a safe way. This review critically analyzes the insights of energetic semiconductor structure lacking to achieve hydroxyl and superoxide radicals mediated antibiotics degrdn., recommends new materials design (Z scheme) and standardization in the exptl. designs, and also informs the influencing parameters on antibiotic degrdn. It further assesses the possibility of recovering value-added chems. from the photocatalytic treatment process and highlights the importance of environmental toxicity anal. Overall, this review will be a resourceful guide for interdisciplinary researchers working on advanced photocatalysis and pharmaceutical pollutant treatment for achieving a sustainable ecol. and initiating a circular economy in chem. industries.
- 3Jiao, Z.; Zhang, Y.; Ouyang, S.; Yu, H.; Lu, G.; Ye, J.; Bi, Y. BiAg alloy nanospheres: a new photocatalyst for H2 evolution from water splitting. ACS Appl. Mater. Interfaces 2014, 6, 19488– 19493, DOI: 10.1021/am506030p3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvVyhu7nJ&md5=30b5cb58fb5201e709254b8918f6c8f9BiAg Alloy Nanospheres: A New Photocatalyst for H2 Evolution from Water SplittingJiao, Zhengbo; Zhang, Yan; Ouyang, Shuxin; Yu, Hongchao; Lu, Gongxuan; Ye, Jinhua; Bi, YingpuACS Applied Materials & Interfaces (2014), 6 (22), 19488-19493CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)We demonstrate for the first time that Bi and BiAg alloy nanospheres, fabricated with a facile hydrothermal method, display evident photocatalytic H2 prodn. activities. Element Bi can serve as an active photocatalyst for both water splitting and photoelectrochem. applications. More interestingly, these activities of Bi can be greatly enhanced by introducing Ag to form BiAg alloy nanoparticles, which may be ascribed to the improved charge sepn. and enlarged carrier concn. The constituent of the BiAg alloy can be rationally tuned by varying the amt. of Ag nanowires, and it is found that Bi0.7Ag0.3 exhibits the highest photoelectrochem. property.
- 4Chaker, H.; Chérif-Aouali, L.; Khaoulani, S.; Bengueddach, A.; Fourmentin, S. Photocatalytic degradation of methyl orange and real wastewater by silver doped mesoporous TiO2 catalysts. J. Photochem. Photobiol., A 2016, 318, 142– 149, DOI: 10.1016/j.jphotochem.2015.11.0254https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFKit7vP&md5=f7e02cdbe42062d84949aa6d202d8a23Photocatalytic degradation of methyl orange and real wastewater by silver doped mesoporous TiO2 catalystsChaker, H.; Cherif-Aouali, L.; Khaoulani, S.; Bengueddach, A.; Fourmentin, S.Journal of Photochemistry and Photobiology, A: Chemistry (2016), 318 (), 142-149CODEN: JPPCEJ; ISSN:1010-6030. (Elsevier B.V.)The photocatalytic activity of silver doped mesoporous TiO2 catalysts was evaluated for water treatment. Doped catalysts were prepd by impregnation-redn with citrate using various Ag loadings (0.5 wt%, 1.5 wt% and 3 wt%) and characterized by X-Ray powder diffraction (XRD), BET and diffuse reflectance UV-vis spectroscopy (DR/UV-vis). Silver doped TiO2 catalysts retain the phys properties of mesoporous TiO2 and its hexagonal order. The degrdn of methyl orange (MO) as a model org pollutant and of a real wastewater effluent was carried out under UVC, UVB, UVA and simulated solar light irradn. Mesoporous TiO2 showed a better activity than P25 TiO2 and photocatalytic performance of silver doped mesoporous TiO2 was enhanced compare to undoped. The mineralization of the org pollutant was investigated by total org carbon (TOC) measurements. The 0.5 wt%Ag/TiO2 exhibited the highest TOC abatement both for the mineralization of MO and of real wastewater under UV and simulated solar light. Moreover, the catalyst was stable and could be used repeatedly. Therefore, this catalyst is promising for photocatalytic wastewater treatment under solar irradn., leading to a cheap technol for developing countries.
- 5Ahmad, K.; Ghatak, H. R.; Ahuja, S. A review on photocatalytic remediation of environmental pollutants and H2 production through water splitting: A sustainable approach. Environ. Technol. Innovation 2020, 19, 100893 DOI: 10.1016/j.eti.2020.100893There is no corresponding record for this reference.
- 6Zhang, J.; Li, L.; Xiao, Z.; Liu, D.; Wang, S.; Zhang, J.; Hao, Y.; Zhang, W. Hollow sphere TiO2–ZrO2 prepared by self-assembly with polystyrene colloidal template for both photocatalytic degradation and H2 evolution from water splitting. ACS Sustainable Chem. Eng. 2016, 4, 2037– 2046, DOI: 10.1021/acssuschemeng.5b013596https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XivFOms7k%253D&md5=cfe6532d00b14c497b33d43079bd74a3Hollow Sphere TiO2-ZrO2 Prepared by Self-Assembly with Polystyrene Colloidal Template for Both Photocatalytic Degradation and H2 Evolution from Water SplittingZhang, Jianqi; Li, Li; Xiao, Zhixin; Liu, Di; Wang, Shuang; Zhang, Jingjing; Hao, Yuting; Zhang, WenzhiACS Sustainable Chemistry & Engineering (2016), 4 (4), 2037-2046CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)On the basis of a self-assembly technique with polystyrene (PS) spheres as colloidal template, the composite TiO2-ZrO2 hollow spheres are synthesized by combining a water bath with a calcining postprocessing method. XRD, UV-vis/DRS, XPS, SEM-EDS, TEM, HR-TEM, and N2 adsorption-desorption measurements are employed to characterize the compn., structure, and morphol. of TiO2-ZrO2 hollow spheres. The results show that TiO2-ZrO2 hollow spheres are mainly TiO2 anatase and retain well the spherical structure of the PS crystal template, whose shell is closely packed by TiO2-ZrO2 nanoparticles, with thickness of ca. 24 nm. The combination of TiO2 and ZrO2 and the special hollow structure are beneficial to improve the photocatalytic activity. TiO2-ZrO2 hollow spheres have remarkable photocatalytic properties under UV light, simulated sunlight, and microwave-assisted three different modes, which can also degrade org. pollutants of different structures. The H2 evolution quantity in 8 h, which is produced by the photolysis of water, is 23.7 μmol, indicating that TiO2-ZrO2 hollow spheres have a certain hydrogen prodn. performance. The results of the trapping expt. indicate that the active radicals •O2-, h+, and •OH- are responsible for the photocatalytic reaction, and the possible reaction mechanism of TiO2-ZrO2 hollow spheres in both photocatalytic degrdn. and photocatalytic H2 evolution from splitting water is also proposed.
- 7Varma, K. S.; Tayade, R. J.; Shah, K. J.; Joshi, P. A.; Shukla, A. D.; Gandhi, V. G. Photocatalytic degradation of pharmaceutical and pesticide compounds (PPCs) using doped TiO2 nanomaterials: A review. Water-Energy Nexus 2020, 3, 46– 61, DOI: 10.1016/j.wen.2020.03.008There is no corresponding record for this reference.
- 8Bhatia, V.; Dhir, A. Transition metal doped TiO2 mediated photocatalytic degradation of anti-inflammatory drug under solar irradiations. J. Environ. Chem. Eng. 2016, 4, 1267– 1273, DOI: 10.1016/j.jece.2016.01.0328https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitlCntrg%253D&md5=e4089fa10c0a229ca971d78134108ddeTransition metal doped TiO2 mediated photocatalytic degradation of anti-inflammatory drug under solar irradiationsBhatia, Vibhu; Dhir, AmitJournal of Environmental Chemical Engineering (2016), 4 (1), 1267-1273CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)Bismuth (Bi) and Nickel (Ni) Doped Titanium Dioxide (TiO2) nanoparticles were synthesized by sol-gel method and the prepd. nanoparticles were characterized by X-Ray Diffraction, Scanning Electron Microscope, UV-vis reflectance spectroscopy and Brunauer-Emmett-Teller (BET) anal. The concn. of dopant in synthesized catalysts was varied from 0.25 to 1.0 wt%. Maximum BET surface area of 47.8 and 45.7 m2/g was obsd. with 0.25 wt% Bi-TiO2 and 0.5 wt% Ni-TiO2, resp. EDX anal. has established the presence of 0.21% Bi ions and 0.36% Ni ions in 0.25 wt% Bi doped TiO2 and 0.5 wt% Ni doped TiO2, resp. Band gap of Bi-TiO2 (0.25 wt%) and Ni-TiO2 (0.5 wt%) was obtained to be 2.99 eV, which is found to be min. among the various synthesized catalysts. The photocatalytic activity of synthesized catalysts were tested and compared with Degussa TiO2 for degrdn. of Ibuprofen (IBP) as a model compd. Bi-TiO2 nanoparticles revealed higher photocatalytic activity when compared to Ni-TiO2 or Degussa TiO2 under solar irradn., which may be attributed to increase in sp. surface area, and decrease in the crystallite size. Maximum of 89% degrdn. was achieved with 0.25% Bi-TiO2 photocatalyst under 6 h of illuminations with a solar light, whereas, 78% degrdn. has been achieved under similar exptl. condition with Ni doped TiO2. The kinetics of the degrdn. of IBP has been explained in terms of the Langmuir-Hinshelwood model and was found to follow first order kinetics with k value of 0.0064 and 0.0046 min-1 with Bi and Ni doped TiO2, resp.
- 9Mathew, S.; Ganguly, P.; Kumaravel, V.; Bartlett, J.; Pillai, S. C. Solar Light-induced Photocatalytic Degradation of Pharmaceuticals in Wastewater Treatment. In Nano-Materials as Photocatalysts for Degradation of Environmental Pollutants, Singh, P.; Borthakur, A.; Mishra, P. K.; Tiwary, D., Eds.; Elsevier, 2020; Chapter 4, pp 65– 78.There is no corresponding record for this reference.
- 10Tayade, R. J.; Kulkarni, R. G.; Jasra, R. V. Transition Metal Ion Impregnated Mesoporous TiO2 for Photocatalytic Degradation of Organic Contaminants in Water. Ind. Eng. Chem. Res. 2006, 45, 5231– 5238, DOI: 10.1021/ie051362o10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsFens70%253D&md5=e9723256e17f812875b6ff0dacc6bce0Transition Metal Ion Impregnated Mesoporous TiO2 for Photocatalytic Degradation of Organic Contaminants in WaterTayade, Rajesh J.; Kulkarni, Ramchandra G.; Jasra, Raksh. V.Industrial & Engineering Chemistry Research (2006), 45 (15), 5231-5238CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)Mesoporous nanocryst. TiO2 was prepd. by hydrolysis of titanium isopropoxide, and the band gap of the TiO2 was modified with the transition metal ions Ag, Co, Cu, Fe, and Ni, having different work functions, by the wet impregnation method. X-ray diffraction (XRD), x-ray photoelectron spectrophotometry, diffuse reflectance spectrophotometry (DRS), SEM, and BET techniques were used for the characterization of the catalysts. By using the DRS technique, the highest red shift of 11 nm and lowest of 1.5 nm were obsd. for Ni- and Fe ion-impregnated catalysts, resp. The investigations were carried out to demonstrate the effect of ionic radius and work function of metal ions on photocatalytic activity of mesoporous nanocryst. TiO2 for degrdn. of acetophenone and nitrobenzene in aq. medium under UV light irradn.
- 11Xiong, Z.; Ma, J.; Ng, W. J.; Waite, T. D.; Zhao, X. S. Silver-modified mesoporous TiO2 photocatalyst for water purification. Water Res. 2011, 45, 2095– 2103, DOI: 10.1016/j.watres.2010.12.01911https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXitFaqurg%253D&md5=1337639a5250674d4251a2cb8f8d7b9eSilver-modified mesoporous TiO2 photocatalyst for water purificationXiong, Zhigang; Ma, Jizhen; Ng, Wun Jern; Waite, T. David; Zhao, X. S.Water Research (2011), 45 (5), 2095-2103CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)Mesoporous anatase (TiO2) was modified with silver (Ag) nanoparticles using a photoredn. method. Performance of the resulting TiO2-Ag nanocomposites for water purifn. was evaluated using degrdn. of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli) under UV irradn. The composites with different Ag loadings were characterized using phys. adsorption of nitrogen, X-ray diffraction, XPS and UV-Visible diffuse reflectance spectroscopic techniques. The results showed that metallic Ag nanoparticles were firmly immobilized on the TiO2 surface, which improved electron-hole sepn. by forming the Schottky barrier at the TiO2-Ag interface. Photocatalytic degrdn. of RhB and inactivation of E. coli effectively occurred in an analogical trend. The deposited Ag slightly decreased adsorption of target pollutants, but greatly increased adsorption of mol. oxygen with the latter enhancing prodn. of reactive oxygen species (ROSs) with concomitant increase in contaminant photodegrdn. The optimal Ag loadings for RhB degrdn. and E. coli disinfection were 0.25 wt% and 2.0 wt%, resp. The composite photocatalysts were stable and could be used repeatedly under UV irradn.
- 12Lin, C. J.; Yang, W.-T.; Chou, C.-Y.; Liou, S. Y. H. Hollow mesoporous TiO2 microspheres for enhanced photocatalytic degradation of acetaminophen in water. Chemosphere 2016, 152, 490– 495, DOI: 10.1016/j.chemosphere.2016.03.01712https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XkslKhsbo%253D&md5=cd22c50ed44b097189adf5f701a70ef4Hollow mesoporous TiO2 microspheres for enhanced photocatalytic degradation of acetaminophen in waterLin, Chin Jung; Yang, Wen-Ta; Chou, Chen-Yi; Liou, Sofia Ya HsuanChemosphere (2016), 152 (), 490-495CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)Hollow core-shell mesoporous TiO2 microspheres were synthesized by a template-free solvothermal route for efficient photocatalytic degrdn. of acetaminophen. X-ray diffraction, SEM, transmission electron microscopy, and Barrett-Joyner-Halenda data revealed a micrometer-sized mesoporous anatase TiO2 hollow sphere with large surface area and efficient light harvesting. For the photocatalytic degrdn. of acetaminophen in 60 min, the conversion fraction of the drug increased from 88% over com. Degussa P25 TiO2 to 94% over hollow spheres with about 25% increase in the initial reaction rate. Even after 10 repeated runs, the recycled hollow spheres showed good photodegrdn. activity. The intermediates generated in the photocatalytic reactions were eventually converted into mols. that are easier to handle. The simple fabrication route would facilitate the development of photocatalysts for the decompn. of environmental contaminants.
- 13Alvarez-Corena, J. R.; Bergendahl, J. A.; Hart, F. L. Advanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identification. J. Environ. Manage. 2016, 181, 544– 551, DOI: 10.1016/j.jenvman.2016.07.01513https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xht1ShsbzN&md5=fcda1324df71478d953b5cd395f5408aAdvanced oxidation of five contaminants in water by UV/TiO2: Reaction kinetics and byproducts identificationAlvarez-Corena, Jose R.; Bergendahl, John A.; Hart, Fred L.Journal of Environmental Management (2016), 181 (), 544-551CODEN: JEVMAW; ISSN:0301-4797. (Elsevier Ltd.)The extent and kinetics of degrdn. of 1,4 dioxane, n-nitrosodimethylamine (NDMA), tris-2-chloroethyl phosphate (TCEP), gemfibrozil, and 17β estradiol in a prepd. aq. matrix by means of UV/TiO2 (UV light/titanium dioxide) oxidn. was evaluated. Degussa P25 TiO2 was employed as a photocatalyst excited by UV light in a 1 L water-jacketed batch photoreactor. The rate of degrdn. was modeled using a pseudo-first order rate model and the Langmuir-Hinshelwood rate model with a high correlation. Degrdn. rate consts. were found to be max. at pH 5.0 and 1.5 g L-1 TiO2 dose. For these conditions first order rate consts., values were as follows: 0.29 min-1 for 1,4 dioxane, 0.50 min-1 for NDMA, 0.12 min-1 for TCEP, 0.61 min-1 for gemfibrozil, and 0.53 min-1 for 17β estradiol. While for the Langmuir-Hinshelwood rate model, the following consts. were found: 0.11 Lmg-1 and 2.81 mgL-1 min-1 for 1,4 dioxane, 0.12 Lmg-1 and 4.35 mgL-1 min-1 for NDMA, 0.06 Lmg-1 and 1.79 mgL-1 min-1 for TCEP, 0.21 Lmg-1 and 3.27 mgL-1 min-1 for gemfibrozil, and 0.15 Lmg-1 and 3.43 mgL-1 min-1 for 17β estradiol. In addn., specific byproducts of degrdn. were identified using GC/MS anal. The results obtained from the kinetics anal. showed that UV/TiO2 oxidn. is a promising process for treating trace org. contaminants in water, but further research is needed to better understand how to incorporate these findings into pilot and full-scale designs. The toxicity of oxidn. byproducts, and their potential for interacting with other compds. should be considered in the treatment of contaminated waters using the UV/TiO2 oxidn. process.
- 14Jin-hui, Z. Research on UV/TiO2 Photocatalytic Oxidation of Organic Matter in Drinking Water and Its Influencing Factors. Procedia Environ. Sci. 2012, 12, 445– 452, DOI: 10.1016/j.proenv.2012.01.302There is no corresponding record for this reference.
- 15Wu, Q.; Zhao, J.; Qin, G.; Wang, C.; Tong, X.; Xue, S. Photocatalytic reduction of Cr(VI) with TiO2 film under visible light. Appl. Catal., B 2013, 142–143, 142– 148, DOI: 10.1016/j.apcatb.2013.04.05615https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXht1eks7nI&md5=22e1357544670e2f773cf21679246dd3Photocatalytic reduction of Cr(VI) with TiO2 film under visible lightWu, Quanping; Zhao, Jun; Qin, Guohui; Wang, Chengyang; Tong, Xinli; Xue, SongApplied Catalysis, B: Environmental (2013), 142-143 (), 142-148CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)The performance of photocatalytic redn. of chromium (VI) via a new TiO2 film and a platinum anode was systematically evaluated. The as-prepd. TiO2 film is composed of a dye-sensitized zone and a catalysis zone. Charge sepn. was accomplished with electron transferring to the catalysis zone and pos. charge transforming to an anode. A powerful redn. ability of the reaction system was achieved in the absence of any orgs. under visible light irradn. Several parameters including pH, dissolved O2, the primary active species, the durability of the as-synthesized film and so on were investigated.
- 16Sudhagar, P.; Devadoss, A.; Nakata, K.; Terashima, C.; Fujishima, A. Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2 Nanostructures through Amplifying Light Reception and Surface States Passivation. J. Electrochem. Soc. 2015, 162, H108– H114, DOI: 10.1149/2.0161503jes16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtFClsrk%253D&md5=9226e2c49b92226a6a725f7e8081fb85Enhanced Photoelectrocatalytic Water Splitting at Hierarchical Gd3+:TiO2 Nanostructures through Amplifying Light Reception and Surface States PassivationSudhagar, P.; Devadoss, Anitha; Nakata, K.; Terashima, C.; Fujishima, A.Journal of the Electrochemical Society (2015), 162 (3), H108-H114CODEN: JESOAN; ISSN:0013-4651. (Electrochemical Society)The effect of rare earth gadolinium (Gd3+) ion doping on optical and photoelectrochem. properties of TiO2 is studied. The hierarchical clump-type TiO2 nanostructure was fabricated using polyvinyl acetate as soft-template. The optical absorbance quantity of TiO2 was strikingly promoted at bandgap energy region (380 nm) by Gd3+ doping, as well as it extend a wide absorbance in visible wavelength region (400-800 nm) elucidating the sub-bandgap formation. As a result, Gd3+:TiO2 exhibits high photocurrent d. than undoped TiO2 in photoelectrocatalytic expts. Another plausible reason for enhancing the photocurrent d. at Gd3+:TiO2 was analyzed through electrochem. impedance spectroscopy. The underlying mechanism of surface states controlled charge transfer at TiO2/electrolyte interfaces affected the photoelectrocatalytic hydrogen fuel generation, and compete with Gd3+ ion doping through bottlenecking of photoelectrons trapping at surface states. The improved charge sepn. (e-/h+) at Gd3+:TiO2 result effective photoelectron collection and thus yield 180 % higher hydrogen gas (∼ 2.34 mL.h-1.cm-2 ) generation compare to pristine TiO2 (1.28 mL.h-1.cm-2) under UV light irradn. The improved optical and charge transfer characteristics of hierarchical TiO2 by Gd3+ ions can be implemented to wide range of other metal oxide based photocatalytic fuel generation.
- 17Naldoni, A.; Altomare, M.; Zoppellaro, G.; Liu, N.; Kment, Š.; Zbořil, R.; Schmuki, P. Photocatalysis with Reduced TiO2: From Black TiO2 to Cocatalyst-Free Hydrogen Production. ACS Catal. 2019, 9, 345– 364, DOI: 10.1021/acscatal.8b0406817https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitlylsLzL&md5=a70417c49844b431e2055bbaa2874c37Photocatalysis with Reduced TiO2: From Black TiO2 to Cocatalyst-Free Hydrogen ProductionNaldoni, Alberto; Altomare, Marco; Zoppellaro, Giorgio; Liu, Ning; Kment, Stepan; Zboril, Radek; Schmuki, PatrikACS Catalysis (2019), 9 (1), 345-364CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. Black TiO2 nanomaterials have recently emerged as promising candidates for solar-driven photocatalytic hydrogen prodn. Despite the great efforts to synthesize highly reduced TiO2, it is apparent that intermediate degree of redn. (namely, gray titania) brings about the formation of peculiar defective catalytic sites enabling cocatalyst-free hydrogen generation. A precise understanding of the structural and electronic nature of these catalytically active sites is still elusive, as well as the fundamental structure-activity relationships that govern formation of crystal defects, increased light absorption, charge sepn., and photocatalytic activity. In this Review, we discuss the basic concepts that underlie an effective design of reduced TiO2 photocatalysts for hydrogen prodn. such as (i) defects formation in reduced TiO2, (ii) anal. of structure deformation and presence of unpaired electrons through ESR spectroscopy, (iii) insights from surface science on electronic singularities due to defects, and (iv) the key differences between black and gray titania, i.e., photocatalysts that require Pt-modification and cocatalyst-free photocatalytic hydrogen generation. Finally, future directions to improve the performance of reduced TiO2 photocatalysts are outlined.
- 18Do, H. H.; Nguyen, D. L. T.; Nguyen, X. C.; Le, T.-H.; Nguyen, T. P.; Trinh, Q. T.; Ahn, S. H.; Vo, D.-V. N.; Kim, S. Y.; Le, Q. V. Recent progress in TiO2-based photocatalysts for hydrogen evolution reaction: A review. Arabian J. Chem. 2020, 13, 3653– 3671, DOI: 10.1016/j.arabjc.2019.12.01218https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXnvVKktQ%253D%253D&md5=563ba32f3b82b214b734932f228c552dRecent progress in TiO2-based photocatalysts for hydrogen evolution reaction: A reviewDo, Ha Huu; Nguyen, Dang Le Tri; Nguyen, Xuan Cuong; Le, Thu-Ha; Nguyen, Thang Phan; Trinh, Quang Thang; Ahn, Sang Hyun; Vo, Dai-Viet N.; Kim, Soo Young; Le, Quyet VanArabian Journal of Chemistry (2020), 13 (2), 3653-3671CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)A review. TiO2 has gained tremendous attention as a cutting-edge material for application in photocatalysis. The performance of TiO2 as a photocatalyst depends on various parameters including morphol., surface area, and crystallinity. Although TiO2 has shown good catalytic activity in various catalysis systems, the performance of TiO2 as a photocatalyst is generally limited due to its low cond. and a wide optical bandgap. Numerous different studies have been devoted to overcome these problems, showing significant improvement in photocatalytic performance. In this study, we summarize the recent progress in the utilization of TiO2 for the photocatalytic hydrogen evolution reaction (HER). Strategies for modulating the properties toward the high photocatalytic activity of TiO2 for HER including structural engineering, compositional engineering, and doping are highlighted and discussed. The advantages and limitations of each modification approach are reviewed. Finally, the remaining obstacles and perspective for the development of TiO2 as photocatalysts toward high efficient HER in the near future are also provided.
- 19Yang, S.; Tang, W.; Ishikawa, Y.; Feng, Q. Synthesis of titanium dioxide with oxygen vacancy and its visible-light sensitive photocatalytic activity. Mater. Res. Bull. 2011, 46, 531– 537, DOI: 10.1016/j.materresbull.2011.01.00419https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXisFeis70%253D&md5=17c7e1b4610591a54f9f90921c13407eSynthesis of titanium dioxide with oxygen vacancy and its visible-light sensitive photocatalytic activityYang, Si-Tao; Tang, Wei-Ping; Ishikawa, Yoshie; Feng, QiMaterials Research Bulletin (2011), 46 (4), 531-537CODEN: MRBUAC; ISSN:0025-5408. (Elsevier Ltd.)A novel active carbon reducing process was developed for the synthesis of titania with oxygen vacancy. In this process a nanocomposite of hydrolyzed titanium(IV) tetra-isopropoxide and the active carbon was annealed in air. The formation reaction, visible-light absorption, and visible-light sensitive photocatalytic activity of the titania with oxygen vacancy samples were investigated using XRD, TG-DTA analyses, FE-SEM, EDS, and measurements of elec. cond., BET sp. surface area and photocatalytic activity. The nonstoichiometric titania with oxygen vacancy sample has a rutile structure and its chem. formula can be written as Ti(IV)1-xTi(III)xO(2-x/2).box.x/2, where .box. is oxygen vacancy. The oxygen vacancy was introduced into the rutile structure by reducing reaction of the active carbon in a phase transformation process from anatase to rutile. The samples showed visible-light absorption with an absorption edge around 570 nm and high surface visible-light sensitive photocatalytic activity.
- 20Hirakawa, H.; Hashimoto, M.; Shiraishi, Y.; Hirai, T. Photocatalytic Conversion of Nitrogen to Ammonia with Water on Surface Oxygen Vacancies of Titanium Dioxide. J. Am. Chem. Soc. 2017, 139, 10929– 10936, DOI: 10.1021/jacs.7b0663420https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFOmtrbL&md5=241bee5e6568ff455e289e7f23d6e585Photocatalytic conversion of nitrogen to ammonia with water on surface oxygen vacancies of titanium dioxideHirakawa, Hiroaki; Hashimoto, Masaki; Shiraishi, Yasuhiro; Hirai, TakayukiJournal of the American Chemical Society (2017), 139 (31), 10929-10936CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Ammonia (NH3) is an essential chem. in modern society. It is currently manufd. by the Haber-Bosch process using H2 and N2 under extremely high-pressure (>200 bar) and high-temp. (>673 K) conditions. Photocatalytic NH3 prodn. from water and N2 at atm. pressure and room temp. is ideal. Several semiconductor photocatalysts have been proposed, but all suffer from low efficiency. Here we report that a com. available TiO2 with a large no. of surface oxygen vacancies, when photoirradiated by UV light in pure water with N2, successfully produces NH3. The active sites for N2 redn. are the Ti3+ species on the oxygen vacancies. These species act as adsorption sites for N2 and trapping sites for the photoformed conduction band electrons. These properties therefore promote efficient redn. of N2 to NH3. The solar-to-chem. energy conversion efficiency is 0.02%, which is the highest efficiency among the early reported photocatalytic systems. This noble-metal-free TiO2 system therefore shows a potential as a new artificial photosynthesis for green NH3 prodn.
- 21Hao, Y.-n.; Chen, T.; Zhang, X.; Zhou, H.; Ma, Y. Ti-Ti σ bond at oxygen vacancy inducing the deep defect level in anatase TiO2 (101) surface. J. Chem. Phys. 2019, 150, 224702 DOI: 10.1063/1.510859521https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtFOktrrN&md5=f3c6106ad675a4a4ec21d28ac7864a5aTi-Ti σ bond at oxygen vacancy inducing the deep defect level in anatase TiO2 (101) surfaceHao, Ya-nan; Chen, Tingwei; Zhang, Xiao; Zhou, He; Ma, YuchenJournal of Chemical Physics (2019), 150 (22), 224702/1-224702/9CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)Using the GW method within many-body perturbation theory, we investigate the quasiparticle structures of defects, including oxygen vacancy, Ti interstitial, and hydroxyl groups, in the anatase TiO2 (101) surface. We find that the deep defect state in this surface obsd. exptl., which is 1 eV below the Fermi level, originates from the σ bond formed between 3d orbitals of the two under-coordinated Ti atoms at the surface oxygen vacancy. Different from the d. functional theory modified with on-site Coulomb terms (DFT + U), the GW method predicts that the localized polaron in anatase (101) is a shallow defect state close to the conduction band bottom. Polaronic states play the role in pinning the Fermi level of anatase near the conduction band bottom. Our GW calcns. can explain satisfactorily the coexistence of shallow and deep defect states in anatase as obsd. in expts. We also find that the conduction band edge of anatase is drawn down greatly after the filling of original empty Ti 3d orbitals by excess electrons, making the calcd. bandgap of the reduced anatase agree well with the expts. This significant difference in the bandgap between the intact and the reduced anatase is missed in DFT + U. (c) 2019 American Institute of Physics.
- 22Wang, Y.; Zhang, M.; Lv, S.; Li, X.; Wang, D.; Song, C. Photogenerated Oxygen Vacancies in Hierarchical Ag/TiO2 Nanoflowers for Enhanced Photocatalytic Reactions. ACS Omega 2020, 5, 13994– 14005, DOI: 10.1021/acsomega.0c0139022https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVGhurfL&md5=6344654ba9d168684220f8e359272c76Photogenerated Oxygen Vacancies in Hierarchical Ag/TiO2 Nanoflowers for Enhanced Photocatalytic ReactionsWang, Ying; Zhang, Miaomiao; Lv, Shuhua; Li, Xiaoqian; Wang, Debao; Song, CaixiaACS Omega (2020), 5 (23), 13994-14005CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)Oxygen vacancy (Vo) creation and morphol. controlling make significant contributions to the electronic and structural regulation of metal oxide semiconductors, yet an investigation about convenient approaches for fabricating hierarchical catalyst with abundant oxygen vacancies still has significant challenges. Here, we report a unique method to create abundant oxygen vacancies in hierarchical Ag/TiO2 nanoflowers during photocatalytic reaction, which is accompanied by light absorption variation and surface plasmon resonance (SPR) enhancement. Its high efficiency of photocatalytic H2 evolution (the highest apparent quantum yield reaches 3.2% at 365 nm) and rhodamine B degrdn. can be considered as benefits from the synergistic effects of the well-arranged hierarchical structure, the photogenerated oxygen vacancies, and the SPR of cocatalyst Ag. This work proposes an effective strategy to optimize the synthesis of regular hierarchical structures and enriches the research on the vital function of oxygen vacancies in photocatalytic reactions.
- 23Bi, X.; Du, G.; Kalam, A.; Sun, D.; Yu, Y.; Su, Q.; Xu, B.; Al-Sehemi, A. G. Tuning oxygen vacancy content in TiO2 nanoparticles to enhance the photocatalytic performance. Chem. Eng. Sci. 2021, 234, 116440 DOI: 10.1016/j.ces.2021.11644023https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvF2rtb0%253D&md5=2e7c550c82189a682dba4c9c342a23d3Tuning oxygen vacancy content in TiO2 nanoparticles to enhance the photocatalytic performanceBi, Xiang; Du, Gaohui; Kalam, Abul; Sun, Dongfeng; Yu, Yuan; Su, Qingmei; Xu, Bingshe; Al-Sehemi, Abdullah G.Chemical Engineering Science (2021), 234 (), 116440CODEN: CESCAC; ISSN:0009-2509. (Elsevier Ltd.)White TiO2 (W-TiO2), gray TiO2 (G-TiO2) and black TiO2 (B-TiO2) have been prepd. through simple annealing process in different atmospheres. The oxygen vacancy content in the TiO2 samples and the relationship between oxygen vacancy and photocatalytic performance have been studied by comprehensive analyses. The XRD peaks slightly move to a low angle and the Raman strongest peak shifts pos. owing to oxygen vacancy and Ti3+. The energy bandgap of G-TiO2 and B-TiO2 is tuned from 3.10 to 3.02 and 1.99 eV. The content of oxygen vacancy is 1%, 4.8% and 7.8% for W-TiO2, G-TiO2 and B-TiO2, resp. The efficiency of NO removal is stable at 34%, 38% and 45%, and the decompn. rate of Rhodamine B under visible light is 75%, 83% and 89% for W-TiO2, G-TiO2 and B-TiO2, resp. The results are significant for the design of high-performance photocatalytic materials in the field of solar energy conversion.
- 24Pedroza-Herrera, G.; Medina-Ramírez, I. E.; Lozano-Álvarez, J. A.; Rodil, S. E. Evaluation of the Photocatalytic Activity of Copper Doped TiO2 nanoparticles for the Purification and/or Disinfection of Industrial Effluents. Catal. Today 2020, 341, 37– 48, DOI: 10.1016/j.cattod.2018.09.01724https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXis1WhsLvF&md5=4733d301098017b7bb742a5c4c1180d0Evaluation of the Photocatalytic Activity of Copper Doped TiO2 nanoparticles for the Purification and/or Disinfection of Industrial EffluentsPedroza-Herrera, Gladis; Medina-Ramirez, Iliana E.; Lozano-Alvarez, Juan Antonio; Rodil, Sandra E.Catalysis Today (2020), 341 (), 37-48CODEN: CATTEA; ISSN:0920-5861. (Elsevier B.V.)In this article, visible light active, copper doped TiO2 nanoparticles are discussed as potential candidates for the tertiary treatment of industrial effluents. Our aim was to develop sustainable photocatalytic materials that exhibit excellent activity and biocompatibility. The photocatalysts were prepd. using a two-step procedure: sol-gel synthesis followed by microwave hydrothermal treatment. Copper (Cu) was chosen as doping agent because it has been previously reported that Cu is a good doping element that improves the photocatalytic performance of TiO2. The incorporation of Cu into the TiO2 matrix was demonstrated by X ray photoelectron spectroscopy and a bandgap redn. down to 2.86 eV was achieved at relatively low doping levels (nominal 2.0%). A moderate photocatalytic activity was obsd. for the degrdn. of diclofenac and for the removal of dissolved org. matter contained in an industrial effluent. The removal efficiency of the nanoparticles increased linearly with the amt. of copper doping. For instance after 7 h of illumination, diclofenac degrdn. efficiencies of 21.41, 28.95 and 33.26% were obsd. for TiO2-Cu (1.0, 1.5 and 2.0%) resp. Meanwhile, disinfection of the effluents was attained within five hours of treatment under visible light, in our irradn. conditions. Hydrogen peroxide improved the photocatalytic activity of the nanoparticles since the release of Cu2+ ions give rise to a combined degrdn. mechanism: photocatalysis + photo-Fenton. The lixiviation of Cu2+ ions was demonstrated by at. absorption spectroscopy. Moreover, The Cu doped TiO2 nanostructures exhibited excellent antibacterial properties against both gram neg. and pos. bacteria and do not exert any cytotoxicity to human blood cells. The biocompatibility of the Cu doped TiO2 nanoparticles combined with their photocatalytic activity under room light illumination suits them as excellent candidates for the development of sustainable environmental remediation technologies.
- 25Armaković, S. J.; Grujić-Brojčin, M.; Šćepanović, M.; Armaković, S.; Golubović, A.; Babić, B.; Abramović, B. F. Efficiency of La-doped TiO2 calcined at different temperatures in photocatalytic degradation of β-blockers. Arabian J. Chem. 2019, 12, 5355– 5369, DOI: 10.1016/j.arabjc.2017.01.00125https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhs1Witb4%253D&md5=a883a27ce202ab6998ad4232a3fb8bb8Efficiency of La-doped TiO2 calcined at different temperatures in photocatalytic degradation of β-blockersArmakovic, Sanja J.; Grujic-Brojcin, Mirjana; Scepanovic, Maja; Armakovic, Stevan; Golubovic, Aleksandar; Babic, Biljana; Abramovic, Biljana F.Arabian Journal of Chemistry (2019), 12 (8), 5355-5369CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)Photocatalytic activity of titania-based photocatalysts doped with 1% La has been tested in UVA radiation-induced degrdn. of two β-blockers - metoprolol tartrate (MET) and propranolol hydrochloride (PRO). Photocatalysts have been synthesized by sol-gel process followed by calcination at various temps. in the range of 450-750°C. The great impact of calcination temp. on the structural, compositional and morphol. properties of prepd. catalysts has been revealed by XRPD, SEM, BET and Raman scattering measurements. Doped catalysts calcined at 450-650°C, with dominant anatase phase and developed mesoporous structure, have displayed higher photocatalytic performance than much less porous samples calcined at 700-750°C, with sodium hexatitanate as dominant phase. Also, La-doped anatase sample has shown higher efficiency in degrdn. of MET and PRO in comparison with the efficiency of undoped TiO2 nanopowders calcined at same temps. The quenching effects of various scavengers suggest that the major role in degrdn. of MET may be attributed to reactive radicals, whereas photogenerated holes are mainly responsible for degrdn. of PRO. Applying d. functional theory (DFT) calcns., we analyzed fundamental structural and electronic properties (total and polar surface areas, frontier MOs, optoelectronic properties and av. local ionization energy surfaces) of MET and PRO mols., which are of significance for the understanding of more effective degrdn. of PRO in comparison with MET.
- 26Zhu, X.; Pei, L.; Zhu, R.; Jiao, Y.; Tang, R.; Feng, W. Preparation and characterization of Sn/La co-doped TiO2 nanomaterials and their phase transformation and photocatalytic activity. Sci. Rep. 2018, 8, 12387 DOI: 10.1038/s41598-018-30050-326https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3c7ptlGitQ%253D%253D&md5=4257f8f3cd53222dad4e7dfa4904752aPreparation and characterization of Sn/La co-doped TiO2 nanomaterials and their phase transformation and photocatalytic activityZhu Xiaodong; Pei Lingxiu; Zhu Ranran; Feng Wei; Zhu Xiaodong; Jiao Yu; Zhu Xiaodong; Feng Wei; Jiao Yu; Tang RenyongScientific reports (2018), 8 (1), 12387 ISSN:.The pure, tin (Sn)-doped, lanthanum (La)-doped and Sn/La co-doped titanium dioxide (TiO2) nanomaterials were synthesized using sol-gel method followed by calcination at the temperature of 360 °C, 450 °C and 600 °C, respectively. The structures of the nanomaterials were characterized by X-ray diffraction (XRD), Thermogravimetric (TG), Differential Thermal Analysis (DTA), Scanning Electron Microscopy (SEM), Energy Dispersive Spectrum (EDS), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectrum (XPS), Diffuse Reflectance Spectrum (DRS), Photoluminescence Spectrum (PL), Brunauer-Emmett-Teller Measurements (BET), respectively. The photocatalytic property of the photocatalysts under UV light was evaluated through the degradation of Rhodamine B (RhB). The results show that the anatase-rutile phase transition is promoted by Sn-doping while La-doping retards the phase transition. However, La doping plays a major role in the process of phase transformation. The photocatalytic activity of pure TiO2 is affected by annealing temperature remarkably and the optimal annealing temperature is 450 °C. The photocatalytic activity of TiO2 is enhanced significantly by Sn and La doping at three different temperatures. Sn/La-TiO2 exhibits the highest degradation rates and the fastest reaction rates probably owing to the synergistic effect of Sn(4+) and La(3+) ions in inhibiting the recombination of photogenerated electron-hole pairs. The formation of extra surface hydroxyl groups and additional surface area are also beneficial for the photocatalytic activity.
- 27Kumar, A.; Choudhary, P.; Kumar, A.; Camargo, P. H. C.; Krishnan, V. Recent Advances in Plasmonic Photocatalysis Based on TiO2 and Noble Metal Nanoparticles for Energy Conversion, Environmental Remediation, and Organic Synthesis. Small 2022, 18, 2101638 DOI: 10.1002/smll.20210163827https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsl2ku7vO&md5=ee5ff8b3e43f24b24b8799923e01f898Recent advances in plasmonic photocatalysis based on TiO2 and noble metal nanoparticles for energy conversion, environmental remediation, and organic synthesisKumar, Ajay; Choudhary, Priyanka; Kumar, Ashish; Camargo, Pedro H. C.; Krishnan, VenkataSmall (2022), 18 (1), 2101638CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Plasmonic photocatalysis has emerged as a prominent and growing field. It enables the efficient use of sunlight as an abundant and renewable energy source to drive a myriad of chem. reactions. For instance, plasmonic photocatalysis in materials comprising TiO2 and plasmonic nanoparticles (NPs) enables effective charge carrier sepn. and the tuning of optical response to longer wavelength regions (visible and near IR). In fact, TiO2-based materials and plasmonic effects are at the forefront of heterogeneous photocatalysis, having applications in energy conversion, prodn. of liq. fuels, wastewater treatment, nitrogen fixation, and org. synthesis. This review aims to comprehensively summarize the fundamentals and to provide the guidelines for future work in the field of TiO2-based plasmonic photocatalysis comprising the above-mentioned applications. The concepts and state-of-the-art description of important parameters including the formation of Schottky junctions, hot electron generation and transfer, near field electromagnetic enhancement, plasmon resonance energy transfer, scattering, and photothermal heating effects have been covered in this review. Synthetic approaches and the effect of various physicochem. parameters in plasmon-mediated TiO2-based materials on performances are discussed. It is envisioned that this review may inspire and provide insights into the rational development of the next generation of TiO2-based plasmonic photocatalysts with target performances and enhanced selectivities.
- 28Kumar, A.; Choudhary, P.; Krishnan, V. Selective and efficient aerobic oxidation of benzyl alcohols using plasmonic Au-TiO2: Influence of phase transformation on photocatalytic activity. Appl. Surf. Sci. 2022, 578, 151953 DOI: 10.1016/j.apsusc.2021.15195328https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1KisbjO&md5=79444127df3002d4db5b175e710f0568Selective and efficient aerobic oxidation of benzyl alcohols using plasmonic Au-TiO2: Influence of phase transformation on photocatalytic activityKumar, Ajay; Choudhary, Priyanka; Krishnan, VenkataApplied Surface Science (2022), 578 (), 151953CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Chem. processes using heterogeneous photocatalytic systems are widely used for the synthesis of valuable fine chems. To improve these chem. processes both environmental and energy aspects must be kept in mind for favorable reaction conditions, such as optimum temp. and atm. pressure. In this study, plasmonic Au nanoparticles (Au NP) dispersed over TiO2 photocatalyst with different phases of TiO2 (amorphous, anatase and rutile) have been synthesized by using a facile sol-gel method followed by calcination for the photocatalytic oxidn. of benzyl alc. (BnOH) to benzaldehyde (BzH) under visible light irradn. at ambient conditions. The best photocatalyst exhibits high surface area and excellent catalytic conversion efficiency (96%) for the oxidn. of BnOH to BzH in less reaction time using a green solvent, acetonitrile at room temp. The detailed optimization of reaction parameters was performed for alc. conversion. In addn. the corresponding green metrics parameters were also calcd. The photocatalyst also shows excellent stability and reusability for multiple cycles. This work suggests that the Au-TiO2 catalyst provides a novel green and sustainable approach for the selective and efficient aerobic oxidn. of BnOH to BzH under visible light irradn. Furthermore, the impact of different phases of TiO2 on the photocatalytic activity has also been discussed.
- 29Kumar, A.; Shankar, K. R.; Kumar, A.; Harith, G.; Krishnan, V. Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteins. J. Environ. Chem. Eng. 2021, 9, 105147 DOI: 10.1016/j.jece.2021.10514729https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjvFKru78%253D&md5=88230008129d52575c8a2ced0f6fe2b6Controlling the kinetics of visible-light-induced photocatalytic performance of gold decorated graphitic carbon nitride nanocomposite using different proteinsKumar, Ajay; Shankar, Konathala Ravi; Kumar, Ashish; Harith, Gurunarayanan; Krishnan, VenkataJournal of Environmental Chemical Engineering (2021), 9 (2), 105147CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)In this work, the interaction of different proteins with two dimensional (2D) graphitic carbon nitride (GCN) nanosheets decorated with gold nanoparticles (Au NP) is reported along with their influence in controlling the visible-light-induced photocatalytic activity. The decoration of Au NP on 2D GCN nanosheets improves the photocatalytic activity as Au NP plays an important role in trapping and storing the conduction band electrons of GCN nanosheets. The structural, morphol. and optical properties of Au-GCN (AGCN) nanocomposite have been investigated using scattering and spectroscopic techniques. Methylene blue (MB) dye was chosen as a representative system for the studying of visible-light-induced photocatalytic activity of AGCN nanocomposite in the presence of different proteins. Bovine serum albumin (BSA), trypsin and cytochrome C having different chain lengths and physicochem. properties were used to control the kinetics of the photocatalytic activity of GCN and AGCN nanocomposites. Due to the simultaneous competitive adsorption of MB and proteins, the photocatalytic activity of the nanocomposites got enhanced in the presence of BSA, while it got inhibited or slowed down in the presence of trypsin and cytochrome C, resp. The obsd. photocatalytic activity could be correlated with the surface charges present on the proteins and the mechanistic understanding developed in this study can be beneficial in controlling the kinetics of the photocatalytic activity of semiconductor-based photocatalysts using proteins as activators or inhibitors.
- 30Kumar, A.; Singla, Y.; Sharma, M.; Bhardwaj, A.; Krishnan, V. Two dimensional S-scheme Bi2WO6–TiO2–Ti3C2 nanocomposites for efficient degradation of organic pollutants under natural sunlight. Chemosphere 2022, 308, 136212 DOI: 10.1016/j.chemosphere.2022.13621230https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XisFGms73O&md5=e2c5ed0e14cc5d5b0272a0c6e569c4c3Two dimensional S-scheme Bi2WO6-TiO2-Ti3C2 nanocomposites for efficient degradation of organic pollutants under natural sunlightKumar, Ashish; Singla, Yash; Sharma, Manisha; Bhardwaj, Akhil; Krishnan, VenkataChemosphere (2022), 308 (Part_1), 136212CODEN: CMSHAF; ISSN:0045-6535. (Elsevier Ltd.)Two-dimensional (2D) materials have fascinated the researchers to exploit their properties including large surface area, ability to act as a support and to form face-to-face interfacial contact with other 2D materials for fabricating efficient photocatalytic materials. In this work, Bi2WO6, TiO2 and Ti3C2 nanosheets have been used synthesizing different series of binary Bi2WO6-TiO2 and ternary Bi2WO6-TiO2-Ti3C2 2D nanocomposites by an electrostatic self-assembly synthesis route. The as-prepd. pristine materials and binary and ternary nanocomposites were characterized by different structural, morphol. and compositional characterization techniques to confirm their successful synthesis and 2D morphol. It was found that the optimized Bi2WO6-TiO2 (20 wt%) and Bi2WO6-TiO2 (20 wt%)-Ti3C2 (5 wt%) nanocomposites showed 97.0% and 98.5% degrdn. of methyl green in 80 min and 40 min, resp., which was higher than their pristine counterparts. The enhanced activity was credited to the large surface area offered by 2D nanocomposites, pollutant adsorption and enhanced photogenerated charge sepn. and transfer facilitated by S-scheme mechanism and face-to-face interfacial contact of different components of these nanocomposites. This work delivers an example of highly efficient 2D nanocomposites and discusses the role of Ti3C2 as an electron acceptor in S-scheme photocatalytic system.
- 31Zhang, W.; Ma, Y.; Zhu, X.; Liu, S.; An, T.; Bao, J.; Hu, X.; Tian, H. Fabrication of Ag decorated g-C3N4/LaFeO3 Z-scheme heterojunction as highly efficient visible-light photocatalyst for degradation of methylene blue and tetracycline hydrochloride. J. Alloys Compd. 2021, 864, 158914 DOI: 10.1016/j.jallcom.2021.15891431https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjtV2rsL0%253D&md5=5978533798cacd07740f0c9d78cae12dFabrication of Ag decorated g-C3N4/LaFeO3 Z-scheme heterojunction as highly efficient visible-light photocatalyst for degradation of methylene blue and tetracycline hydrochlorideZhang, Weijin; Ma, Yongxiang; Zhu, Xiuhua; Liu, Shujie; An, Tao; Bao, Jinyu; Hu, Xiaoying; Tian, HongweiJournal of Alloys and Compounds (2021), 864 (), 158914CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)The discharge of industrial wastewater poses serious concerns to the environment and human health. Therefore, urgent development of simple and efficient catalysts for removal of pollutants is required. In this study, a novel ternary nanocomposite Ag/g-C3N4/LaFeO3 (A/CN/LFO) was synthesized for the degrdn. of dye and pharmaceutical wastewater. The catalyst was prepd. by decorating Ag nanoparticles (NPs) on g-C3N4/LaFeO3 (CN/LFO) Z-scheme heterojunction and formation of Schottky junctions with LaFeO3 (LFO) and g-C3N4 (CN). The formed hybrid structure between metal and Z-scheme heterojunction induced directional transfer of electrons or holes from the Z-scheme heterojunction to metal, providing max. sepn. between electrons and holes for more efficient redox reactions. Consequently, the ternary nanocomposite displayed optimized efficiencies toward the photocatalytic degrdn. of methylene blue (MB) and tetracycline hydrochloride (TC) under visible-light irradn., estd. to 98.97% (90 min) and 94.93% (120 min), resp. These values were almost 4.81 times and 3.88 times higher than those of pristine LaFeO3, resp. The charge transfer mechanism and pollutant degrdn. pathway were also studied. The data revealed that Ag decorated Z-scheme heterojunction showed efficient light absorption and sepn. of photogenerated carriers, which might be useful for large-scale practical applications related to wastewater treatment and pollution control.
- 32Tian, H.; Wan, C.; Xue, X.; Hu, X.; Wang, X. Effective Electron Transfer Pathway of the Ternary TiO2/RGO/Ag Nanocomposite with Enhanced Photocatalytic Activity under Visible Light. Catalysts 2017, 7, 156, DOI: 10.3390/catal705015632https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFymtbfI&md5=4d51f7aea907265a4c08f8a19521765fEffective electron transfer pathway of the ternary TiO2/RGO/Ag nanocomposite with enhanced photocatalytic activity under visible lightTian, Hongwei; Wan, Chenxing; Xue, Xin; Hu, Xiaoying; Wang, XiaoyiCatalysts (2017), 7 (5), 156/1-156/15CODEN: CATACJ; ISSN:2073-4344. (MDPI AG)Mesoporous TiO2/reduced graphene oxide/Ag (TiO2/RGO/Ag) ternary nanocomposite with an effective electron transfer pathway is obtained by an electrostatic self-assembly method and photo-assisted treatment. Compared with bare mesoporous TiO2 (MT) and mesoporous TiO2/RGO (MTG), the ternary mesoporous TiO2/RGO/Ag (MTGA) nanocomposite exhibited superior photocatalytic performance for the degrdn. of methylene blue (MB) under visible light, and the degrdn. rate reached 0.017 min-1, which was 3.4-times higher than that of MTG. What is more, the degrdn. rate of MTGA nanocomposite after three cycle times is 91.2%, and the compn. is unchanged. In addn., we found that the OH·, h+ and esp. O2·- contribute to the high photocatalytic activity of MTGA for MB degrdn. It is proposed that Ag nanoparticles can form the local surface plasmon resonance (LSPR) to absorb the visible light and distract the electrons into MT, and RGO can accept the electrons from MT to accelerate the sepn. efficiency of photogenerated carriers. The establishment of MTGA ternary nanocomposite makes the three components act synergistically to enhance the photocatalytic performance.
- 33Tian, H.; Shen, K.; Hu, X.; Qiao, L.; Zheng, W. N, S co-doped graphene quantum dots-graphene-TiO2 nanotubes composite with enhanced photocatalytic activity. J. Alloys Compd. 2017, 691, 369– 377, DOI: 10.1016/j.jallcom.2016.08.26133https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsV2is7zI&md5=65cf4cf9e5551f25527360df4484ac1bN, S co-doped graphene quantum dots-graphene-TiO2 nanotubes composite with enhanced photocatalytic activityTian, Hongwei; Shen, Kai; Hu, Xiaoying; Qiao, Liang; Zheng, WeitaoJournal of Alloys and Compounds (2017), 691 (), 369-377CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)N, S co-doped graphene quantum dots (N, S-GQDs) -reduced graphene oxide- (rGO) -TiO2 nanotubes (TiO2NT) composites were prepd. by a facile alk. hydrothermal reaction and phys. stirring process. The apparent rate const. of the N, S-GQDs + 10%rGO + TiO2NT composite, exhibiting the highest photodegrdn. efficiency, is 1.8 times and 16.3 times higher than those of 10% rGO + TiO2NT and pure TiO2NT, resp., for the degrdn. of methyl orange (MO) under visible light irradn. (λ > 400 nm). Our work could provide new insights into the fabrication of GQDs-semiconductor composites as high performance photocatalysts and broaden the range of doped GQDs widely used for environmental protection.
- 34Meng, Z.; Zhou, B.; Xu, J.; Li, Y.; Hu, X.; Tian, H. Heterostructured Nitrogen and Sulfur co-doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic Activity. Chem. Res. Chin. Univ. 2020, 36, 1045– 1052, DOI: 10.1007/s40242-020-0175-234https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFCht7rN&md5=13d04a8d4aa20c8a3f6dd7b744508dd2Heterostructured Nitrogen and Sulfur Co-doped Black TiO2/g-C3N4 Photocatalyst with Enhanced Photocatalytic ActivityMeng, Zeshuo; Zhou, Bo; Xu, Jian; Li, Yaxin; Hu, Xiaoying; Tian, HongweiChemical Research in Chinese Universities (2020), 36 (6), 1045-1052CODEN: CRCUED; ISSN:1005-9040. (Jilin University)Conventional titanium dioxide(TiO2) photocatalyst could absorb only UV light due to its wide bandgap. In this paper, black TiO2 with narrow bandgap was prepd. by introducing oxygen vacancies. Meanwhile, nitrogen(N) and sulfur(S) elements were doped to further broaden the visible light response range of TiO2(NS-BT), and then heterostructured N,S-doped black TiO2/g-C3N4(CN/NS-BT) was successfully constructed by easily accessible route. The formation of CN/NS-BT heterojunction structure increased the generation and sepn. efficiency of photogenerated electron-hole pairs, as well as accelerated the transfer rate of the carriers. The as-prepd. CN/NS-BT exhibited excellent photocatalytic performance towards the degrdn. of Rhodamine B(RhB) under visible light irradn. with satisfactory stability. The apparent reaction rate const. of CN/NS-BT(0.0079) was 15.8-fold higher than that of com. P25(0.0005). The structure, morphol., chem. compn. and optical properties of the as-prepd. CN/NS-BT were characterized by various anal. methods, and possible photocatalytic enhancement mechanism was proposed. Overall, CN/NS-BT composites look promising as photocatalytic material for future environmental treatment.
- 35Santos, L. M.; Machado, W. A.; França, M. D.; Borges, K. A.; Paniago, R. M.; Patrocinio, A. O. T.; Machado, A. E. H. Structural characterization of Ag-doped TiO2 with enhanced photocatalytic activity. RSC Adv. 2015, 5, 103752– 103759, DOI: 10.1039/C5RA22647C35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvVygtrrK&md5=7ed281e717d9fa2f0761a9499588077fStructural characterization of Ag-doped TiO2 with enhanced photocatalytic activitySantos, Lidiaine M.; Machado, Werick A.; Franca, Marcela D.; Borges, Karen A.; Paniago, Roberto M.; Patrocinio, Antonio O. T.; Machado, Antonio E. H.RSC Advances (2015), 5 (125), 103752-103759CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)As the amt. of silver is increased, the resulting TiO2 nanoparticles exhibit smaller particle size (from 27 nm for bare TiO2 to 12 nm for TiO2-Ag 5.0%) and larger surface area. XPS confirms that during the sintering step of the resultant powder at 400°C for 5 h, ca. 34% of the silver content is converted to Ag0via thermal decompn. of Ag2O. The data also indicates the presence of highly oxidized silver species, such as Ag2+ and Ag3+. X-ray diffractograms and Raman spectroscopy confirm that the cryst. structure of the TiO2 matrix corresponds to the anatase polymorph; however, the presence of the dopant leads to an increase in the system disorder due to a higher concn. of oxygen vacancies, as also confirmed by XPS. TiO2-Ag 5.0% exhibited the highest photocatalytic activity towards mineralization of the E102 tartrazine azo-dye, being 78% faster than bare TiO2 at optimum pH conditions (pH = 6.9). Upon light excitation, the oxidized silver cations are reduced to Ag0, leading to an improvement in visible light absorption due to the surface plasmon resonance effect. The recycling of the photocatalyst showed that the enhanced photocatalytic activity is maintained, which can be assocd. with the redn. of charge recombination at the oxide surface and the enhanced visible light harvesting.
- 36Chakhtouna, H.; Benzeid, H.; Zari, N.; Qaiss, A. e. k.; Bouhfid, R. Recent progress on Ag/TiO2 photocatalysts: photocatalytic and bactericidal behaviors. Environ. Sci. Pollut. Res. 2021, 28, 44638– 44666, DOI: 10.1007/s11356-021-14996-y36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisFegtrbO&md5=b1099342b50cac034c852c8e03fd3dceRecent progress on Ag/TiO2 photocatalysts: photocatalytic and bactericidal behaviorsChakhtouna, Hanane; Benzeid, Hanane; Zari, Nadia; Qaiss, Abou el kacem; Bouhfid, RachidEnvironmental Science and Pollution Research (2021), 28 (33), 44638-44666CODEN: ESPLEC; ISSN:0944-1344. (Springer)A review. Abstr.: For many decades, titanium dioxide (TiO2) semiconductor has been extensively applied in several environmental applications due to its higher photocatalytic performances toward different org. pollutants, pharmaceutical compds., and bacteria. However, its shortfall response to visible light, and the expeditious recombination rate of the photogenerated electron-hole pairs, hampers its utilization. Doping TiO2 semiconductor with silver nanoparticles is a sound strategy to (1) extend its photocatalytic activity to visible light, (2) prevent the electron/holes pairs recombination due to the formation of the Schottky barrier at the interfaces with TiO2 that act as an electron-trapping center, and (3) enhance its bactericide performances. This focuses on the recent progress on silver-doped titanium dioxide (Ag/TiO2)-based photocatalysts. It addresses a wide range of Ag/TiO2 synthesis techniques, their physicochem. properties and discusses thoroughly the important role of silver (Ag) nanoparticles in enhancing the removal capacity and antibacterial performances of the Ag/TiO2 photocatalysts.
- 37Gogoi, D.; Namdeo, A.; Golder, A. K.; Peela, N. R. Ag-doped TiO2 photocatalysts with effective charge transfer for highly efficient hydrogen production through water splitting. Int. J. Hydrogen Energy 2020, 45, 2729– 2744, DOI: 10.1016/j.ijhydene.2019.11.12737https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitlajtbbO&md5=65ca3a673eead3fcb79bb9f1138ac1afAg-doped TiO2 photocatalysts with effective charge transfer for highly efficient hydrogen production through water splittingGogoi, Devipriya; Namdeo, Ashutosh; Golder, Animes Kumar; Peela, Nageswara RaoInternational Journal of Hydrogen Energy (2020), 45 (4), 2729-2744CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)The development of efficient metal doped semiconductors for solar energy harvesting to produce hydrogen has attracted significant attention. Herein, the H2 generation over Ag-doped TiO2 photocatalyst, synthesized using a simple and cost-effective method based on chem. redn., was reported. The Ag/TiO2 exhibited an absorption peak in the visible region and the redn. of the bandgap to 2.5 eV due to surface plasmonic resonance (SPR). XPS revealed the presence of oxygen vacancies and 11% of Ag in Ti-Ag-O phase. The effect of reaction time and photocatalyst loading in the absence and presence of sacrificial reagents (alcs. and sulfur) on water splitting was studied and compared the activity of Ag/TiO2 with that of bare TiO2. The H2 prodn. rate of 23.5 mmol g-1 h-1 (with an apparent quantum yield of 19%), over 1.5Ag/TiO2, was the highest ever reported so far. The obsd. higher activity could mainly be attributed to the existence of oxygen vacancies and the Ti-Ag-O phase. The photocatalyst was stable for three consecutive cycles in both the presence and absence of sacrificial reagents. This study offers new insights into the rational design of metal-support hybrid structures for hydrogen prodn. through photocatalytic water splitting.
- 38Varma, R. S.; Thorat, N.; Fernandes, R.; Kothari, D. C.; Patel, N.; Miotello, A. Dependence of photocatalysis on charge carrier separation in Ag-doped and decorated TiO2 nanocomposites. Catal. Sci. Technol. 2016, 6, 8428– 8440, DOI: 10.1039/C6CY01605G38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1ygur%252FL&md5=86ed397216f3e28651795bde0dd65ad4Dependence of photocatalysis on charge carrier separation in Ag-doped and decorated TiO2 nanocompositesVarma, Ranjana S.; Thorat, Nirmala; Fernandes, R.; Kothari, D. C.; Patel, N.; Miotello, A.Catalysis Science & Technology (2016), 6 (24), 8428-8440CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)Two model Ag-TiO2 nanocomposite systems have been investigated with the aim of understanding the relationship between the photocatalytic efficiency and the contributions of various structures resulting in charge carrier sepn., charge transfer and extension of light absorption to the visible range. The first model system is based on a composite scheme consisting of TiO2 decorated with Ag nanoparticles (NPs). The second composite scheme consists of TiO2 simultaneously doped and decorated with Ag NPs. Ag-TiO2 nanocomposites contg. various concns. (0.5 to 6 at%) of Ag nanoparticles were prepd., and the photocatalytic degrdn. of p-nitrophenol (PNP) and methylene blue (MB) were investigated. Compared to the Ag-decorated samples, the Ag-doped and decorated samples show enhanced activity due to the synergistic effects of the Schottky barrier, doping and the anatase + brookite mixed phase. It was obsd. from PL and fluorescence lifetime studies that the charge carrier lifetime correlates with the relative photonic efficiency of the photocatalytic activity. An optimum Ag concn. is required to obtain the max. lifetime of the photo-generated charges. The photocatalytic activity does not show any correlation to the amt. of visible light absorption, to plasmonic effects, or to band-gap redn. Decorating with silver nanoparticles aids electron transfer and creates electron traps in the form of oxygen vacancies on the surface of TiO2. For the Ag-TiO2 system, the photocatalytic activity is directly proportional to the lifetime of the photogenerated charge carrier.
- 39Zhao, Z.-J.; Hwang, S. H.; Jeon, S.; Hwang, B.; Jung, J.-Y.; Lee, J.; Park, S.-H.; Jeong, J.-H. Three-dimensional plasmonic Ag/TiO2 nanocomposite architectures on flexible substrates for visible-light photocatalytic activity. Sci. Rep. 2017, 7, 8915 DOI: 10.1038/s41598-017-09401-z39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cbgtlWgug%253D%253D&md5=27318cb0ca29efb36078d50430cffa31Three-dimensional plasmonic Ag/TiO2 nanocomposite architectures on flexible substrates for visible-light photocatalytic activityZhao Zhi-Jun; Park Sang-Hu; Zhao Zhi-Jun; Hwang Soon Hyoung; Jeon Sohee; Hwang Boyeon; Jung Joo-Yun; Lee Jihye; Jeong Jun-Ho; Hwang Soon Hyoung; Hwang BoyeonScientific reports (2017), 7 (1), 8915 ISSN:.In this study, a periodic three-dimensional (3D) Ag/TiO2 nanocomposite architecture of nanowires was fabricated on a flexible substrate to enhance the plasmonic photocatalytic activity of the composite. Layer-by-layer nanofabrication based on nanoimprint lithography, vertical e-beam evaporation, nanotransfer, and nanowelding was applied in a new method to create different 3D Ag/TiO2 nanocomposite architectures. The fabricated samples were characterized by scanning electron microscopy, transmission electron microscopy, focused ion-beam imaging, X-ray photoelectron spectrometry, and UV-visible spectroscopy. The experiment indicated that the 3D nanocomposite architectures could effectively enhance photocatalytic activity in the degradation of methylene blue solution under visible light irradiation. We believe that our method is efficient and stable, which could be applied to various fields, including photocatalysis, solar energy conversion, and biotechnology.
- 40Zhang, S.; Wang, L.; Liu, C.; Luo, J.; Crittenden, J.; Liu, X.; Cai, T.; Yuan, J.; Pei, Y.; Liu, Y. Photocatalytic wastewater purification with simultaneous hydrogen production using MoS2 QD-decorated hierarchical assembly of ZnIn2S4 on reduced graphene oxide photocatalyst. Water Res. 2017, 121, 11– 19, DOI: 10.1016/j.watres.2017.05.01340https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXnslOnu7o%253D&md5=edb6f2d5262c75df2d620cdebb71e0d9Photocatalytic wastewater purification with simultaneous hydrogen production using MoS2 QD-decorated hierarchical assembly of ZnIn2S4 on reduced graphene oxide photocatalystZhang, Shuqu; Wang, Longlu; Liu, Chengbin; Luo, Jinming; Crittenden, John; Liu, Xia; Cai, Tao; Yuan, Jili; Pei, Yong; Liu, YutangWater Research (2017), 121 (), 11-19CODEN: WATRAG; ISSN:0043-1354. (Elsevier Ltd.)It is attractive to photocatalytically purify wastewater and simultaneously convert solar energy into clean hydrogen energy. However, it is still a challenge owing to the relatively low photocatalytic efficiency of photocatalysts. In this study, we synthesized a molybdenum disulfide (MoS2) quantum dot-decorated 3D nanoarchitecture (MoS2QDs) of indium zinc sulfide (ZnIn2S4) and reduced grapheme oxide (MoS2QDs@ZnIn2S4@RGO) photocatalyst using a simple solvothermal method. The RGO promotes the electron transfer, and the highly dispersed MoS2QDs provides numerous catalytic sites. The photocatalytic purifn. of rhodamine B (RhB), eosin Y (EY), fulvic acid (FA), methylene blue (MB) and p-nitrophenol (PNP) in simulated wastewaters were further tested. The degrdn. efficiencies and TOC removal were 91% and 75% for PNP, 92.2% and 72% for FA, 98.5% and 80% for MB, 98.6% and 84% for EY, and 98.8% and 88% for RhB, resp. (Corganics = 20 mg/L, Ccatalyst = 1.25 g/L, t = 12 h, Ilight = 3.36 × 10-5 E L-1 s-1). Among these tests, the highest hydrogen prodn. was achieved (45 μmol) during RhB degrdn. Both exptl. and calculational results prove that lower LUMO (lowest unoccupied mol. orbit) level of org. mols. was available for transferring electrons to catalysts, resulting in more efficient hydrogen prodn. Significantly, the removal efficiencies of natural org. substances in actual river water reached 76.3-98.4%, and COD reduced from 32 to 16 mg/L with 13.8 μmol H2 prodn. after 12 h.
- 41Hippargi, G.; Anjankar, S.; Krupadam, R. J.; Rayalu, S. S. Simultaneous wastewater treatment and generation of blended fuel methane and hydrogen using Au-Pt/TiO2 photo-reforming catalytic material. Fuel 2021, 291, 120113 DOI: 10.1016/j.fuel.2020.12011341https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvVejt7g%253D&md5=2f5229cbf1d286b70ef68ed6db6f0405Simultaneous wastewater treatment and generation of blended fuel methane and hydrogen using Au-Pt/TiO2 photo-reforming catalytic materialHippargi, Girivyankatesh; Anjankar, Swapna; Krupadam, Reddithota J.; Rayalu, Sadhana S.Fuel (2021), 291 (), 120113CODEN: FUELAC; ISSN:0016-2361. (Elsevier Ltd.)In this work, we report the generation of blended fuel of hydrogen and methane by using simultaneous photocatalysis and photoreforming reactions. A photocatalyst Au-Pt/TiO2 has been designed rationally and synthesized for the efficient electron transfer from Au to Pt and surface ensemble effects which improved the yield of hydrogen and methane. The distribution of Au and Pt nanoparticles were detd. by using electron microscope investigations. The nanocatalyst was further studied for structural elucidation by using X-ray diffraction and optical spectroscopy. It was obsd. that the nanoparticles of Au and Pt dispersed on the TiO2 responsible for facilitation of electron transfer in UV and visible region. This mechanism easily excites TiO2 for catalytic transformation of carboxylic acid to hydrogen and methane. Under UV-Visible light (400 W) the newly developed catalyst reports effective prodn. of hydrogen and methane at the rate of 9386 and 2208μmol/h (14725 and 62579μmol/h/g), resp. from acetic acid with apparent quantum yield of 3.85% at the bandgap of 3.2 eV. This catalytic prodn. of hydrogen and methane (hythane gas) was examd. using acetic acid enriched wastewater. The blended fuel obtained can be used in automobiles as the fuel with lower emissions compared with methane alone as the fuel.
- 42Jeon, T. H.; Koo, M. S.; Kim, H.; Choi, W. Dual-Functional Photocatalytic and Photoelectrocatalytic Systems for Energy- and Resource-Recovering Water Treatment. ACS Catal. 2018, 8, 11542– 11563, DOI: 10.1021/acscatal.8b0352142https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVWrtb%252FF&md5=98081e22770561c5605c2a4b7c28d187Dual-Functional Photocatalytic and Photoelectrocatalytic Systems for Energy- and Resource-Recovering Water TreatmentJeon, Tae Hwa; Koo, Min Seok; Kim, Hyejin; Choi, WonyongACS Catalysis (2018), 8 (12), 11542-11563CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)A review. The solar-driven photo(electro)catalytic process is a key technol. for utilization of solar energy. It is being intensively investigated for application to environmental remediation and solar fuel prodn. Although both environmental and energy applications operate on the basis of the same principle of photoinduced interfacial charge transfer, most previous studies have focused on either the environmental or energy process only since these two processes require very different catalyst properties and reaction conditions. This Perspective describes a dual-functional photo(electro)catalytic process that enables water treatment along with the simultaneous recovery of energy (e.g., H2 and H2O2) or resources (e.g., metal ions) and discusses the status and perspectives of this emerging technol. The essential feature of the process is to utilize the hole oxidn. power for the degrdn. of water pollutants and the electron redn. power for the recovery of energy and resources from wastewaters at the same time. Various PC, PEC, and photovoltaic-driven electrochem. (PV-EC) processes with different dual-functional purposes (e.g., pollutant removal combined with H2 or H2O2 prodn., heavy-metal recovery, denitrification, fuel cell) are introduced and discussed. The reviewed technol. should offer chances for the development of next-generation water treatment processes based on the water-solar energy nexus.
- 43Pitchaimuthu, S.; Sridharan, K.; Nagarajan, S.; Ananthraj, S.; Robertson, P.; Kuehnel, M. F.; Irabien, Á.; Maroto-Valer, M. Solar Hydrogen Fuel Generation from Wastewater─Beyond Photoelectrochemical Water Splitting: A Perspective. Energies 2022, 15, 7399, DOI: 10.3390/en1519739943https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xis1Khs7nN&md5=48bac680bd059fb285817d22979f387dSolar Hydrogen Fuel Generation from Wastewater-Beyond Photoelectrochemical Water Splitting: A PerspectivePitchaimuthu, Sudhagar; Sridharan, Kishore; Nagarajan, Sanjay; Ananthraj, Sengeni; Robertson, Peter; Kuehnel, Moritz F.; Irabien, Angel; Maroto-Valer, MercedesEnergies (Basel, Switzerland) (2022), 15 (19), 7399CODEN: ENERGA; ISSN:1996-1073. (MDPI AG)A review. Green hydrogen-a carbon-free renewable fuel-has the capability to decarbonise a variety of sectors. The generation of green hydrogen is currently restricted to water electrolyzers. The use of freshwater resources and crit. raw materials, however, limits their use. Alternative water splitting methods for green hydrogen generation via photocatalysis and photoelectrocatalysis (PEC) have been explored in the past few decades; however, their com. potential still remains unexploited due to the high hydrogen generation costs. Novel PEC-based simultaneous generation of green hydrogen and wastewater treatment/high-value product prodn. is therefore seen as an alternative to conventional water splitting. Interestingly, the org./inorg. pollutants in wastewater and biomass favorably act as electron donors and facilitate the dual-functional process of recovering green hydrogen while oxidising the org. matter. The generation of green hydrogen through the dual-functional PEC process opens up opportunities for a circular economy. It further enables the end-of-life commodities to be reused, recycled and resourced for a better life-cycle design while being economically viable for commercialisation. This review brings together and critically analyses the recent trends towards simultaneous wastewater treatment/biomass reforming while generating hydrogen gas by employing the PEC technol. We have briefly discussed the tech. challenges assocd. with the tandem PEC process, new avenues, techno-economic feasibility and future directions towards achieving net neutrality.
- 44Liu, J.; An, T.; Li, G.; Bao, N.; Sheng, G.; Fu, J. Preparation and characterization of highly active mesoporous TiO2 photocatalysts by hydrothermal synthesis under weak acid conditions. Microporous Mesoporous Mater. 2009, 124, 197– 203, DOI: 10.1016/j.micromeso.2009.05.00944https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXnvVCnurk%253D&md5=720f13589938f283bb9a5c5f63bcf17dPreparation and characterization of highly active mesoporous TiO2 photocatalysts by hydrothermal synthesis under weak acid conditionsLiu, Jikai; An, Taicheng; Li, Guiying; Bao, Ningzhong; Sheng, Guoying; Fu, JiamoMicroporous and Mesoporous Materials (2009), 124 (1-3), 197-203CODEN: MIMMFJ; ISSN:1387-1811. (Elsevier Inc.)Mesoporous TiO2 photocatalysts have been synthesized in acetic acid aq. solns. by using the amphiphilic triblock copolymer (Pluronic P123) template. The prepd. photocatalysts were characterized by means of X-ray diffraction, transmission electron microscopy and nitrogen adsorption/desorption anal. The phase and structural qualities of the obtained mesoporous TiO2 have been improved by using hydrothermal treatment. The hydrolysis reaction of titanium sources has been controlled by using a low concd. acetic acid aq. soln. used as both hydrolytic retardants and acid catalysts because of the strong chelating effect and acidity of acetic acid. The obtained mesoporous TiO2 exhibits uniform mesoporous structure with different mean pore sizes of up to 9.0 nm. The photocatalytic activity of the obtained photocatalysts was investigated, using di-Me phthalate as a modal pollutant. Over 90% of di-Me phthalate can be photocatalytically degraded within 2 h under UV irradn. in the presence of the obtained photocatalysts with a concn. of 2 g/L. The calcination temp. is the most remarkable factor that can affect the ultimate photocatalytic activity of the prepd. photocatalysts.
- 45Naik, B.; Desai, V.; Kowshik, M.; Prasad, V. S.; Fernando, G. F.; Ghosh, N. N. Synthesis of Ag/AgCl–mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coli. Particuology 2011, 9, 243– 247, DOI: 10.1016/j.partic.2010.12.00145https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXotVGntbw%253D&md5=4998f07bb3de2377f751f98677a1921bSynthesis of Ag/AgCl-mesoporous silica nanocomposites using a simple aqueous solution-based chemical method and a study of their antibacterial activity on E. coliNaik, Bhanudas; Desai, Vilas; Kowshik, Meenal; Prasad, Vadakkethonippurathu Sivankutty; Fernando, Gerard Franklyn; Ghosh, Narendra NathParticuology (2011), 9 (3), 243-247CODEN: PARTC5; ISSN:1674-2001. (Elsevier B.V.)Simple aq. soln.-based chem. methods have been developed for the synthesis of Ag/AgCl nanoparticle-mesoporous silica nanocomposites. Ag loading in the mesoporous silica was accomplished using a wet-impregnation method. The AgCl-mesoporous silica nanocomposite material (AgCl-mSi) was synthesized by using a one pot' method. Synthesized materials were characterized using X-ray diffraction, N2 adsorption-desorption anal. and high-resoln. transmission electron microscopy. Antibacterial activity of the synthesized materials was investigated against Escherichia coli (E. coli) using the conventional plate-count method. All the materials showed high antibacterial activity even when the percentage loading of Ag in the nanocomposite was as low as 10 wt%.
- 46Yuan, J.; Chen, M.; Shi, J.; Shangguan, W. Preparations and photocatalytic hydrogen evolution of N-doped TiO2 from urea and titanium tetrachloride. Int. J. Hydrogen Energy 2006, 31, 1326– 1331, DOI: 10.1016/j.ijhydene.2005.11.01646https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XlsFKqsrY%253D&md5=62ee803ccc7fbe514746b87cd6d8c604Preparations and photocatalytic hydrogen evolution of N-doped TiO2 from urea and titanium tetrachlorideYuan, Jian; Chen, Mingxia; Shi, Jianwei; Shangguan, WenfengInternational Journal of Hydrogen Energy (2006), 31 (10), 1326-1331CODEN: IJHEDX; ISSN:0360-3199. (Elsevier Ltd.)Nitrogen (N)-doped TiO2 samples with high sp. surface areas were directly prepd. by heating the mixt. of urea and TiO2, where the TiO2 was obtained with titanium tetrachloride as precursor. The absorption spectrum of the N-doped TiO2 shifted to wavelength up to 600 nm with increasing urea contents. X-ray photoelectron spectroscopic measurements showed that the N presented in TiO2 was in the state of both molecularly chemisorbed N2 and substituted N. While both of them contribute to the response to visible light, the latter gave the prepd. samples with hydrogen evolution under visible light. The apparent photocatalytic activity of water splitting demonstrated as high amt. of H2 evolution was partly due to the phase transformation from anatase to rutile for the N-doped TiO2.
- 47Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B: Condens. Matter Mater. Phys. 1999, 59, 1758– 1775, DOI: 10.1103/PhysRevB.59.175847https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXkt12nug%253D%253D&md5=78a73e92a93f995982fc481715729b14From ultrasoft pseudopotentials to the projector augmented-wave methodKresse, G.; Joubert, D.Physical Review B: Condensed Matter and Materials Physics (1999), 59 (3), 1758-1775CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Blochl's projector augmented wave (PAW) method is derived. The total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy functional. The Hamilton operator, the forces, and the stress tensor are derived for this modified PAW functional. A simple way to implement the PAW method in existing plane-wave codes supporting US pseudopotentials is pointed out. In addn., crit. tests are presented to compare the accuracy and efficiency of the PAW and the US pseudopotential method with relaxed-core all-electron methods. These tests include small mols. (H2, H2O, Li2, N2, F2, BF3, SiF4) and several bulk systems (diamond, Si, V, Li, Ca, CaF2, Fe, Co, Ni). Particular attention is paid to the bulk properties and magnetic energies of Fe, Co, and Ni.
- 48Kresse, G.; Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 1996, 6, 15– 50, DOI: 10.1016/0927-0256(96)00008-048https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XmtFWgsrk%253D&md5=779b9a71bbd32904f968e39f39946190Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis setKresse, G.; Furthmuller, J.Computational Materials Science (1996), 6 (1), 15-50CODEN: CMMSEM; ISSN:0927-0256. (Elsevier)The authors present a detailed description and comparison of algorithms for performing ab-initio quantum-mech. calcns. using pseudopotentials and a plane-wave basis set. The authors will discuss: (a) partial occupancies within the framework of the linear tetrahedron method and the finite temp. d.-functional theory, (b) iterative methods for the diagonalization of the Kohn-Sham Hamiltonian and a discussion of an efficient iterative method based on the ideas of Pulay's residual minimization, which is close to an order N2atoms scaling even for relatively large systems, (c) efficient Broyden-like and Pulay-like mixing methods for the charge d. including a new special preconditioning optimized for a plane-wave basis set, (d) conjugate gradient methods for minimizing the electronic free energy with respect to all degrees of freedom simultaneously. The authors have implemented these algorithms within a powerful package called VAMP (Vienna ab-initio mol.-dynamics package). The program and the techniques have been used successfully for a large no. of different systems (liq. and amorphous semiconductors, liq. simple and transition metals, metallic and semi-conducting surfaces, phonons in simple metals, transition metals and semiconductors) and turned out to be very reliable.
- 49Kresse, G.; Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B: Condens. Matter Mater. Phys. 1996, 54, 11169– 11186, DOI: 10.1103/PhysRevB.54.1116949https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28Xms1Whu7Y%253D&md5=9c8f6f298fe5ffe37c2589d3f970a697Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis setKresse, G.; Furthmueller, J.Physical Review B: Condensed Matter (1996), 54 (16), 11169-11186CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)The authors present an efficient scheme for calcg. the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay's DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrixes will be discussed. This approach is stable, reliable, and minimizes the no. of order Natoms3 operations. In the second part, we will discuss an efficient mixing scheme also based on Pulay's scheme. A special "metric" and a special "preconditioning" optimized for a plane-wave basis set will be introduced. Scaling of the method will be discussed in detail for non-self-consistent and self-consistent calcns. It will be shown that the no. of iterations required to obtain a specific precision is almost independent of the system size. Altogether an order Natoms2 scaling is found for systems contg. up to 1000 electrons. If we take into account that the no. of k points can be decreased linearly with the system size, the overall scaling can approach Natoms. They have implemented these algorithms within a powerful package called VASP (Vienna ab initio simulation package). The program and the techniques have been used successfully for a large no. of different systems (liq. and amorphous semiconductors, liq. simple and transition metals, metallic and semiconducting surfaces, phonons in simple metals, transition metals, and semiconductors) and turned out to be very reliable.
- 50Perdew, J. P.; Chevary, J. A.; Vosko, S. H.; Jackson, K. A.; Pederson, M. R.; Singh, D. J.; Fiolhais, C. Atoms, molecules, solids, and surfaces: Applications of the generalized gradient approximation for exchange and correlation. Phys. Rev. B: Condens. Matter Mater. Phys. 1992, 46, 6671– 6687, DOI: 10.1103/PhysRevB.46.667150https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK38XlvFyks7c%253D&md5=e52b617f523b1a8c545707544ce01d05Atoms, molecules, solids, and surfaces: applications of the generalized gradient approximation for exchange and correlationPerdew, John P.; Chevary, J. A.; Vosko, S. H.; Jackson, Koblar A.; Pederson, Mark R.; Singh, D. J.; Fiolhais, CarlosPhysical Review B: Condensed Matter and Materials Physics (1992), 46 (11), 6671-87CODEN: PRBMDO; ISSN:0163-1829.Generalized gradient approxns. (GGA's) seek to improve upon the accuracy of the local-spin-d. (LSD) approxn. in electronic-structure calcns. Perdew and Wang have developed a GGA based on real-space cutoff of the spurious long-range components of the second-order gradient expansion for the exchange-correlation hole. Authors have found that this d. functional performs well in numerical tests for a variety of systems: Total energies of 30 atoms are highly accurate. Ionization energies and electron affinities are improved in a statistical sense, although significant interconfigurational and interterm errors remain. Accurate atomization energies are found for seven hydrocarbon mols., with a rms error per bond of 0.1 eV, compared with 0.7 eV for the LSD approxn. and 2.4 eV for the Hartree-Fock approxn. For atoms and mols., there is a cancellation of error between d. functionals for exchange and correlation, which is most striking whenever the Hartree-Fock result is furthest from expt. The surprising LSD underestimation of the lattice consts. of Li and Na by 3-4% is cor., and the magnetic ground state of solid Fe is restored. The work function, surface energy (neglecting the long-range contribution), and curvature energy of a metallic surface are all slightly reduced in comparison with LSD. Taking account of the pos. long-range contribution, authors find surface and curvature energies in good agreement with exptl. or exact values. Finally, a way is found to visualize and understand the nonlocality of exchange and correlation, its origins, and its phys. effects.
- 51Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, 3865– 3868, DOI: 10.1103/PhysRevLett.77.386551https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK28XmsVCgsbs%253D&md5=55943538406ee74f93aabdf882cd4630Generalized gradient approximation made simplePerdew, John P.; Burke, Kieron; Ernzerhof, MatthiasPhysical Review Letters (1996), 77 (18), 3865-3868CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)Generalized gradient approxns. (GGA's) for the exchange-correlation energy improve upon the local spin d. (LSD) description of atoms, mols., and solids. We present a simple derivation of a simple GGA, in which all parameters (other than those in LSD) are fundamental consts. Only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked. Improvements over PW91 include an accurate description of the linear response of the uniform electron gas, correct behavior under uniform scaling, and a smoother potential.
- 52Monkhorst, H. J.; Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B: Condens. Matter Mater. Phys. 1976, 13, 5188– 5192, DOI: 10.1103/PhysRevB.13.5188There is no corresponding record for this reference.
- 53Dudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P. Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U study. Phys. Rev. B: Condens. Matter Mater. Phys. 1998, 57, 1505– 1509, DOI: 10.1103/PhysRevB.57.150553https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXlsVarsQ%253D%253D&md5=9b4f0473346679cb1a8dce0ad7583153Electron-energy-loss spectra and the structural stability of nickel oxide: An LSDA+U studyDudarev, S. L.; Botton, G. A.; Savrasov, S. Y.; Humphreys, C. J.; Sutton, A. P.Physical Review B: Condensed Matter and Materials Physics (1998), 57 (3), 1505-1509CODEN: PRBMDO; ISSN:0163-1829. (American Physical Society)By taking better account of electron correlations in the 3d shell of metal ions in Ni oxide it is possible to improve the description of both electron energy loss spectra and parameters characterizing the structural stability of the material compared with local spin d. functional theory.
- 54Kim, S.; Ji, S.; Kim, K. H.; Roh, S. H.; Cho, Y.; Lee, C.-L.; Lee, K.-S.; Choi, D.-G.; Choi, H.; Kim, J. K.; Park, J. H. Revisiting surface chemistry in TiO2: A critical role of ionic passivation for pH-independent and anti-corrosive photoelectrochemical water oxidation. Chem. Eng. J. 2021, 407, 126929 DOI: 10.1016/j.cej.2020.12692954https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFChtLbL&md5=a490d8920415f980cb22171f63590f0dRevisiting surface chemistry in TiO2: A critical role of ionic passivation for pH-independent and anti-corrosive photoelectrochemical water oxidationKim, Sungsoon; Ji, Seulgi; Kim, Kwang Hee; Roh, Seung Hun; Cho, Yoonjun; Lee, Chang-Lyoul; Lee, Kug-Seung; Choi, Dae-Geun; Choi, Heechae; Kim, Jung Kyu; Park, Jong HyeokChemical Engineering Journal (Amsterdam, Netherlands) (2021), 407 (), 126929CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)TiO2 photoanodes suffer from low catalytic activity and poor stability under acidic media for water oxidn. Here, pH-independent high-efficiency photoelectrochem. (PEC) water oxidn. and prolonged stability via simple ionic passivation of rutile TiO2 (rTiO2) surface are reported. The controlled surface passivation by hydroxide ions (OH-) onto the rTiO2 surface (OH-rTiO2) enables extraordinarily high PEC performance and long-term durability independent of the pH value of electrolyte. The OH-rTiO2 photoanode shows a charge transfer efficiency of ∼ 100% at 1.23 V vs. RHE over the entire pH range (pH 0 ∼ pH 14) without incorporation of any co-catalysts, hole scavengers, or over-layers, which implies that the mol. surface passivation by hydroxide ions successfully promotes the water oxidn. reaction pathway. According to the d. functional theory (DFT) calcns., the OH-rTiO2 surface can possess increased hydroxide ion coverage, faster decay of the pos. surface charge in acidic environments, and weakened H+ adsorption for pH > 7, which enable enhanced water oxidn. performance independent of the pH value of the electrolyte. Thus, the report proves that the ionic passivation by hydroxide ions can affect PEC performances and durability of photoanode materials for pH-universal photoelectrochem. water oxidn.
- 55Sanjinés, R.; Tang, H.; Berger, H.; Gozzo, F.; Margaritondo, G.; Levy, F. Electronic structure of anatase TiO2 oxide. J. Appl. Phys. 1994, 75, 2945– 2951, DOI: 10.1063/1.35619055https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXit1Ontrg%253D&md5=853970b4a902d9558bc0c2906fc8d0ebElectronic structure of anatase TiO2 oxideSanjines, R.; Tang, H.; Berger, H.; Gozzo, F.; Margaritondo, G.; Levy, F.Journal of Applied Physics (1994), 75 (6), 2945-51CODEN: JAPIAU; ISSN:0021-8979.Photoemission spectroscopy was used to investigate the electronic structure of TiO2 anatase single crystals and polycryst. thin films. The stoichiometry and the degree of oxidn. of as-grown crystals, as-deposited films, as well as of thermally annealed samples in different atmospheres, were analyzed, based on the Ti 2p and O 1s core levels, with an energy resoln. of 0.4 eV. The exptl. d. of states (DOS) was found to be in agreement with the theor. DOS reported in the literature for anatase crystals, and shows some characteristics similar to the exptl. DOS reported for rutile crystals. In reduced samples, the exptl. DOS is characterized by intense emission in the region of O 2p bonding orbitals, and does not exhibit an appreciable d. of states in the band gap. As-grown crystals exhibit small band gap emission (a few percent of the valence band VB signal) at about 0.8 eV, which is attributed to Ti3+ (3d) defect states. Annealing the crystals at high temps. in O2 or subsequent thermal redn. in an Ar-H2 mixt. (95%-5%) produces nearly stoichiometric surfaces with smaller or undetectable d. of Ti3+ states. In addn., some redistribution of the spectral wt. is obsd. in the VB spectra.
- 56Bharti, B.; Kumar, S.; Lee, H.-N.; Kumar, R. Formation of oxygen vacancies and Ti 3+ state in TiO 2 thin film and enhanced optical properties by air plasma treatment. Sci. Rep. 2016, 6, 32355 DOI: 10.1038/srep3235556https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsVChu73N&md5=335afc5714d6ad61382647447ae2ab26Formation of oxygen vacancies and Ti3+ state in TiO2 thin film and enhanced optical properties by air plasma treatmentBharti, Bandna; Kumar, Santosh; Lee, Heung-No; Kumar, RajeshScientific Reports (2016), 6 (), 32355CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)This is the first time we report that simply air plasma treatment can also enhances the optical absorbance and absorption region of titanium oxide (TiO2) films, while keeping them transparent. TiO2 thin films having moderate doping of Fe and Co exhibit significant enhancement in the aforementioned optical properties upon air plasma treatment. The moderate doping could facilitate the formation of charge trap centers or avoid the formation of charge recombination centers. Variation in surface species viz. Ti3+, Ti4+, O2-, oxygen vacancies, OH group and optical properties was studied using X-ray photon spectroscopy (XPS) and UV-Vis spectroscopy. The air plasma treatment caused enhanced optical absorbance and optical absorption region as revealed by the formation of Ti3+ and oxygen vacancies in the band gap of TiO2 films. The samples were treated in plasma with varying treatment time from 0 to 60 s. With the increasing treatment time, Ti3+ and oxygen vacancies increased in the Fe and Co doped TiO2 films leading to increased absorbance; however, the increase in optical absorption region/red shift (from 3.22 to 3.00 eV) was obsd. in Fe doped TiO2 films, on the contrary Co doped TiO2 films exhibited blue shift (from 3.36 to 3.62 eV) due to Burstein Moss shift.
- 57Jaiswal, R.; Patel, N.; Kothari, D.; Miotello, A. Improved visible light photocatalytic activity of TiO2 co-doped with Vanadium and Nitrogen. Appl. Catal., B 2012, 126, 47– 54, DOI: 10.1016/j.apcatb.2012.06.03057https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xhtlaiur7N&md5=ef5570f8e64bfb6c63cec489470dff48Improved visible light photocatalytic activity of TiO2 co-doped with Vanadium and NitrogenJaiswal, R.; Patel, N.; Kothari, D. C.; Miotello, A.Applied Catalysis, B: Environmental (2012), 126 (), 47-54CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)V- and N-codoped TiO2 photo-catalyst is synthesized by sol-gel method to sensitize TiO2 to visible light. The concns. of V and N were varied and optimized to enhance photo-catalytic activity. To increase the active surface area, the cryst. powder was ball milled to obtain nanosized particles. The photo-catalysts were characterized by Micro-Raman, TEM, XPS and UV-visible (in diffused reflectance mode) techniques. The co-doped TiO2 photocatalyst displayed narrower band gap (2.3 eV) compared to singly doped TiO2 catalyst, V (2 at.%)-doped (2.42 eV), N (4 at.%)-doped (2.95 eV), and undoped TiO2 (3.13 eV). The photocatalytic activity for the degrdn. of Rhodamine B (an org. dye) under visible light irradn. obtained with co-doped TiO2 photo-catalyst is significantly better as compared to the undoped, V-doped, and N-doped TiO2. The incorporation of V and N in TiO2 lattice induces isolated energy levels near the conduction and valence bands, resp., causing an effective narrowing of the band gap. Due to the low dopants concns., these energy levels can also act as traps for photoexcited holes or electrons thus reducing the recombination between photo-generated charges. Both these effects, band narrowing and enhanced charge sepn. produce synergistic effects to increase the photocatalytic activity of V-N-codoped TiO2.
- 58Wint, T. H. M.; Smith, M. F.; Chanlek, N.; Chen, F.; Oo, T. Z.; Songsiriritthigul, P. Physical origin of diminishing photocatalytic efficiency for recycled TiO2 nanotubes and Ag-loaded TiO2 nanotubes in organic aqueous solution. Catalysts 2020, 10, 737, DOI: 10.3390/catal1007073758https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVShsL%252FJ&md5=5579289a4554a6ac8f9a2ff6994854e3Physical origin of diminishing photocatalytic efficiency for recycled TiO2 Nanotubes and Ag-Loaded TiO2 Nanotubes in organic aqueous solutionWint, Theint Hay Mar; Smith, Michael F.; Chanlek, Narong; Chen, Fuming; Oo, Than Zaw; Songsiriritthigul, PrayoonCatalysts (2020), 10 (7), 737CODEN: CATACJ; ISSN:2073-4344. (MDPI AG)Arrays of titania nanotubes (TiO2NTs) were developed by electrochem. anodization and doped with silver on their surface by photodeposition to achieve TiO2NTs/Ag. It is found that only anatase TiO2NTs were formed, with the preferential growth direction perpendicular to the titanium substrate, and with the length and diam. of ∼2μm and 90-120 nm, resp. The presence of Ag on the surface of TiO2NTs was also confirmed. The TiO2NTs and TiO2NTs/Ag were used as photocatalysts to decolorize the methylene blue (MB) aq. soln. The photodegrdn. efficiency (PDE) is as high as 83% for TiO2NTs and 98% for TiO2NTs/Ag photocatalysts. This work focused on the investigation of the stability and recyclability of these photocatalysts in terms of efficiency and its phys. origin by surface anal. using XPS. It is found that PDE diminishes from 83% to 76% in TiO2NTs upon eight recycling runs and from 98% to 80% in TiO2NTs/Ag upon six recycling runs. The XPS anal. revealed that the phys. origin of diminishing efficiency is the carbon contamination on the surface of recycled TiO2NTs and a combination of carbon contamination and Ag leaching in recycled TiO2NTs/Ag.
- 59Thiel, J.; Pakstis, L.; Buzby, S.; Raffi, M.; Ni, C.; Pochan, D. e. J.; Shah, S. I. Antibacterial properties of silver-doped titania. Small 2007, 3, 799– 803, DOI: 10.1002/smll.20060048159https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXls1Wqurk%253D&md5=ca507d96435f1663b384f3279d87807eAntibacterial properties of silver-doped titaniaThiel, J.; Pakstis, L.; Buzby, S.; Raffi, M.; Ni, C.; Pochan, D. J.; Shah, S. IsmatSmall (2007), 3 (5), 799-803CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Silver-doped titania nanoparticles (see image) in specific concns. show a higher efficacy than pure silver nanoparticles towards the inhibition and annihilation of E. coli bacteria. The doped titania particles are synthesized via a sol-gel method. Antibacterial studies of the silver-doped titania particles in both a liq.-nutrient growth medium and on agar plates are shown; this approach may offer a simple low-cost method for fabricating antibacterial surfaces.
- 60Wagner, C.; Riggs, W.; Davis, L.; Moulder, J. Handbook of X-ray Photoelectron Spectroscopy, Muilenberg, G. E., Ed.; Perkin-Elmer Corporation: Eden Prairie, Minnesota, 1979; p 38.There is no corresponding record for this reference.
- 61Vasil’kov, A. Y.; Dovnar, R. I.; Smotryn, S. M.; Iaskevich, N. N.; Naumkin, A. V. Plasmon resonance of silver nanoparticles as a method of increasing their antibacterial action. Antibiotics 2018, 7, 80, DOI: 10.3390/antibiotics703008061https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVWqsbvN&md5=9623598270f25b5bb503a8996cefefd1Plasmon resonance of silver nanoparticles as a method of increasing their antibacterial actionVasil'kov, Alexander Yu.; Dovnar, Ruslan I.; Smotryn, Siarhei M.; Iaskevich, Nikolai N.; Naumkin, Alexander V.Antibiotics (Basel, Switzerland) (2018), 7 (3), 80CODEN: ABSNC4; ISSN:2079-6382. (MDPI AG)In this article, a series of silver-contg. dressings are prepd. by metal-vapor synthesis (MVS), and their antibacterial properties are investigated. The antibacterial activity of the dressings contg. silver nanoparticles (AgNPs) against some Gram-pos., and Gram-neg. microorganisms (Staphylococcus aureus, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Moraxella spp.) has been detd. Based on the plasmon resonance frequency of these nanoparticles, the frequency of laser irradn. of the dressing was chosen. The gauze bandage examd. showed pronounced antibacterial properties, esp. to Staphylococcus aureus strain. When 470 nm laser radiation, with a power of 5 mW, was applied for 5 min, 4 h after inoculating the Petri dish, and placing a bandage contg. silver nanoparticles on it, the antibacterial effect of the latter significantly increased-both against Gram-pos. and Gram-neg. microorganisms. The structure and chem. compn. of the silver-contg. nanocomposite were studied by transmission electron microscopy (TEM), XPS and extended X-ray absorption fine structure (EXAFS). The synthesized AgNPs demonstrate narrow and monomodal particle size distribution with an av. size of 1.75 nm. Atoms of metal in Ag/bandage system are mainly in Ag0 state, and the oxidized atoms are in the form of Ag-Ag-O groups.
- 62Guan, W.; Ji, F.; Xie, Z.; Li, R.; Mei, N. Preparation and photocatalytic performance of nano-TiO2 codoped with iron III and lanthanum III. J. Nanomater. 2015, 2015, 1– 13, DOI: 10.1155/2015/869821There is no corresponding record for this reference.
- 63Dal’Toé, A. T.; Colpani, G. L.; Padoin, N.; Fiori, M. A.; Soares, C. Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV–visible light. Appl. Surf. Sci. 2018, 441, 1057– 1071, DOI: 10.1016/j.apsusc.2018.01.29163https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtlagurw%253D&md5=1b994d85c6486f96b23b8abb52cb547bLanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible lightDal'Toe, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Marcio Antonio; Soares, CintiaApplied Surface Science (2018), 441 (), 1057-1071CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepd. using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization anal. revealed that La doping slightly changed the cryst. phase of TiO2, increased the amt. of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plasmon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amt. of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addn., Ag-La possibly decreased the semiconductor surface energy, which acted pos. in the redn. of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradn. compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradn. was proposed.
- 64Guo, J.; Cai, X.; Li, Y.; Zhai, R.; Zhou, S.; Na, P. The preparation and characterization of a three-dimensional titanium dioxide nanostructure with high surface hydroxyl group density and high performance in water treatment. Chem. Eng. J. 2013, 221, 342– 352, DOI: 10.1016/j.cej.2013.02.00564https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXlsFCjsLk%253D&md5=3d28f1bf8a6daf778c6e3b904f04e14dThe preparation and characterization of a three-dimensional titanium dioxide nanostructure with high surface hydroxyl group density and high performance in water treatmentGuo, Jingwei; Cai, Xiaojiao; Li, Yuan; Zhai, Ruiguo; Zhou, Shimin; Na, PingChemical Engineering Journal (Amsterdam, Netherlands) (2013), 221 (), 342-352CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)A 3D TiO2 nanostructure consisting of a nanoparticle core and needle-like surface was fabricated. The effects of Ti4+ concn., stirring methods and stirring time for TiO2 prepn. were discussed with results from transmission and SEM; meanwhile, the TiO2 growth mechanism was illustrated by morphol. evolution and crystn. of TiO2 spheres. The spherical diam. could be easily controlled by altering the concn. of precursor using a mech. stirring method. XPS, Fourier transform IR spectrometry and thermogravimetric anal. were used to confirm the compn. of TiO2 spheres rich with hydroxyl groups. The product showed excellent ability for As(V) and Cr(VI) removal and could be sepd. using sedimentation. Most of the ions could be removed in less than 1 h, and TiO2 had max. adsorption capacities of 59.7 mg g-1 for As(V) and 21.92 mg g-1 for Cr(VI). The high performance of self-assembled 3D TiO2 in water treatment was due to (1) its large hydroxyl group d. and high sp. surface area and (2) its 3D nanostructure consisting of a nanoparticle core and needle-like surface.
- 65Wang, B.; Zhang, G.; Sun, Z.; Zheng, S.; Frost, R. L. A comparative study about the influence of metal ions (Ce, La and V) doping on the solar-light-induced photodegradation toward rhodamine B. J. Environ. Chem. Eng. 2015, 3, 1444– 1451, DOI: 10.1016/j.jece.2015.05.00765https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXos1emu7w%253D&md5=b29546f65ab78a7e7740c81ecce1513cA comparative study about the influence of metal ions (Ce, La and V) doping on the solar-light-induced photodegradation toward rhodamine BWang, Bin; Zhang, Guangxin; Sun, Zhiming; Zheng, Shuilin; Frost, Ray L.Journal of Environmental Chemical Engineering (2015), 3 (3), 1444-1451CODEN: JECEBG; ISSN:2213-3437. (Elsevier Ltd.)Water contamination by the textile dye effluents has become a serious environmental issue, which are threatening to the human health and biol. diversity. The TiO2 photocatalysis has been proven to be used to remove textile dyes in water. In order to improve its solar-light activity, three metal ions, including cerium (Ce), lanthanum (La) and vanadium (V), were selected as dopants to prep. metal ions doped TiO2 particles by sol-gel method. The synthesized particles were characterized by X-ray diffraction, field SEM, UV-vis diffuse reflectance spectroscopy and XPS. Through the physicochem. properties of the resulting metal ions doped TiO2 particles, we found that characteristics of dopants could strongly affect the cryst. phase and crystallite size, the optical absorption spectrum and the bandgap energy of the modified TiO2 catalysts, and consequently influence the photocatalytic ability. We investigated the link between dopant's characteristics and photoactivity of the doped catalysts, and deduced that the existence of dopant in the modified catalysts is crucial. In the case of Ce or La doping, the dopants homogeneously dispersed on the surface of TiO2 particles as oxides and interacted with TiO2 particles via RE-O-Ti bond. Nevertheless, the V species successfully entered the TiO2 lattice and substituted for Ti4+ due to its similar ionic radius with Ti. The photocatalytic activities of Ce-, La-, or V-doped TiO2 photocatalysts were evaluated by the degrdn. of rhodamine B under simulated solar-light illumination. In our case, only the doping of Ce or V could drive efficient solar-light activity. The bandgap energy of 1.0%-Ce-TiO2 was narrowed to 2.70 eV and the removal ratio for dye could raise up to 83% with a relatively high calcination temp.
- 66Lei, X.; Chen, C.; Li, X.; Xue, X.; Yang, H. Characterization and photocatalytic performance of La and C co-doped anatase TiO2 for photocatalytic reduction of Cr (VI). Sep. Purif. Technol. 2016, 161, 8– 15, DOI: 10.1016/j.seppur.2016.01.03066https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1Oisb0%253D&md5=051bc6c9e66db5fcd51b6c6d2e98e1c9Characterization and photocatalytic performance of La and C co-doped anatase TiO2 for photocatalytic reduction of Cr(VI)Lei, X. F.; Chen, C.; Li, X.; Xue, X. X.; Yang, H.Separation and Purification Technology (2016), 161 (), 8-15CODEN: SPUTFP; ISSN:1383-5866. (Elsevier B.V.)The La and C co-doped anatase TiO2 nano-materials were synthesized by a hydrothermal method. The structures of La and C co-doped TiO2 were characterized by XRD, FT-IR, XPS, DRS, SEM and nitrogen adsorption-desorption isotherms. The results indicated that pH values have a greater effect on the cryst. phase, crystal size and crystallinity degree of TiO2. The La and C co-doping could inhibit the phase transformation and crystallite growth of TiO2. The photocatalytic activities of La and C co-doped TiO2 for photocatalytic redn. of Cr(VI) under visible light irradn. using different La contents were also studied. The La and C co-doped TiO2 nano-materials with La:Ti wt. ratio of 0.3 exhibits the highest photocatalytic activity for Cr(VI) photocatalytic redn. under visible light irradn., which can be attributed to the synergic effect of the higher BET surface area, surface hydroxyl content and optimum La contents.
- 67Sing, K. S. W. Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure Appl. Chem. 1985, 57, 603– 619, DOI: 10.1351/pac19855704060367https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2MXhvFWrtb4%253D&md5=4fbbea83b3a13b5f22e6d26e5d0ab20cReporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984)Sing, K. S. W.; Everett, D. H.; Haul, R. A. W.; Moscou, L.; Pierotti, R. A.; Rouquerol, J.; Siemieniewska, T.Pure and Applied Chemistry (1985), 57 (4), 603-19CODEN: PACHAS; ISSN:0033-4545.Problems and ambiguities in reporting data are discussed. Procedures and terminol. for reporting data re recommended.
- 68Raj, K. J. S.; Viswanathan, B. Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutile. Indian J. Chem., Sect. A: Inorg., Phys., Theor. Anal. 2009, 48, 1378– 138268https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhsFWhtL%252FJ&md5=a0d2e7bf56e9b60ccd4cf75000cc5820Effect of surface area, pore volume and particle size of P25 titania on the phase transformation of anatase to rutileRaj, K. Joseph Antony; Viswanathan, B.Indian Journal of Chemistry, Section A: Inorganic, Bio-inorganic, Physical, Theoretical & Analytical Chemistry (2009), 48A (10), 1378-1382CODEN: ICACEC; ISSN:0376-4710. (National Institute of Science Communication and Information Resources)The effect of calcination on P25 TiO2 at different temps. was studied by XRD, N adsorption-desorption isotherm, BET-surface area, pore vol., pore size, particle size and crystallite size to understand the conversion of anatase phase to rutile phase. The fraction of anatase and rutile was detd. using XRD. Although the crystallinity remains the same, the phase change of anatase to rutile is inevitable with temp. The isotherms show the nonporous characteristics of the P25 samples. In addn., nitrogen adsorption by the samples decreased appreciably with crystallinity. The pore vol. and BET surface area show a large decrease at 900°. The particle size, crystallite size, and pore size show an increasing trend with increase in temp. Anal. of the phys. characteristics indicates that P25 titania samples can be used for catalytic applications at <500°.
- 69Deiana, C.; Fois, E.; Coluccia, S.; Martra, G. Surface Structure of TiO2 P25 Nanoparticles: Infrared Study of Hydroxy Groups on Coordinative Defect Sites. J. Phys. Chem. C 2010, 114, 21531– 21538, DOI: 10.1021/jp107671k69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsVGksLbO&md5=3d10104e2f98bf7d9f1abe6745cea0d3Surface Structure of TiO2 P25 Nanoparticles: Infrared Study of Hydroxy Groups on Coordinative Defect SitesDeiana, Chiara; Fois, Ettore; Coluccia, Salvatore; Martra, GianmarioJournal of Physical Chemistry C (2010), 114 (49), 21531-21538CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Surface hydroxy groups are known to play a significant role in the photocatalytic behavior of TiO2. The mol. or dissociative character of H2O adsorption on titania is strongly affected by the local surface structure, but dissocn., producing -OH, should prevail on surface sites with a high degree of coordinative unsatn. Here we report an IR investigation of hydroxy groups on low coordination sites of TiO2 P25 (Degussa), a com. titania powder considered a staple in the field of heterogeneous photocatalysis. The presence of coordinatively defective surface terminations well agrees with the roughness of the border of TiO2 particles obsd. by high resoln. transmission electron microscopy. Furthermore, IR spectra of adsorbed CO were used to probe the Lewis acidity of surface Ti4+ ions exposed after the removal of water mols. and hydroxy groups. Evidence for two addnl. types of surface cationic sites with respect those reported in the literature was found.
- 70Bendahou, K.; Cherif, L.; Siffert, S.; Tidahy, H.; Benaissa, H.; Aboukais, A. The effect of the use of lanthanum-doped mesoporous SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts for total oxidation of toluene. Appl. Catal., A 2008, 351, 82– 87, DOI: 10.1016/j.apcata.2008.09.00170https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlWkur%252FK&md5=ad48d3824a0055cc5149306e89fa2e3bThe effect of the use of lanthanum-doped mesoporous SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts for total oxidation of tolueneBendahou, K.; Cherif, L.; Siffert, S.; Tidahy, H. L.; Benaissa, H.; Aboukais, A.Applied Catalysis, A: General (2008), 351 (1), 82-87CODEN: ACAGE4; ISSN:0926-860X. (Elsevier B.V.)Platinum and palladium were supported on a mesoporous SBA-15 for total oxidn. of toluene. The effects of the use of lanthanum-doped SBA-15 on the performance of Pt/SBA-15 and Pd/SBA-15 catalysts and on the total oxidn. of toluene were evaluated. Lanthanum-substituted mesoporous SBA-15 mol. sieve was prepd. by direct synthesis and post-synthesis procedures using lanthanum nitrate as source. By post-synthesis procedure, La was ion-exchanged on calcined silica. Characterizations by at. absorption, x-ray diffraction, nitrogen adsorption, 29Si MAS NMR and FT-IR spectroscopy were carried out to evaluate the efficiency of the incorporation of lanthanum by these procedures. Lanthanum was well incorporated into the SBA-15 structure only by post-synthesis procedure. Structural and textural evolutions of LaSBA-PS (post-synthesis) material were studied according to the Si/La ratio. These LaSBA-15 mesoporous mol. sieves retain the hexagonal order and phys. properties of siliceous SBA-15 material. After removing the surfactant mols. by calcinations, 1% of platinum or 0.5% of palladium was impregnated on SBA-15 or LaSBA-PS (Si/La = 20) via incipient wetness technique using resp. hexachloroplatinic acid and palladium nitrate as the Pt and Pd sources. The activity for toluene total oxidn. of the pre-reduced samples follows this order: 0.5% Pd/SBA-15 > 1% Pt/SBA-15 > 0.5% Pd/LaSBA-PS > 1% Pt/LaSBA-PS. 0.5% Pd/SBA-15 was a interesting catalyst for VOC oxidn. However, the lower activity of the lanthanum catalysts could be explained by patches of LaOX residing on the surface of the metal particles (particularly on Pd) and/or to the interaction between the metal and LaSBA-PS which modifies the electron d. of the metal. For the Pt-based catalyst the obsd. higher dispersion of platinum species for Pt/LaSBA-PS and thus to the increase of the Pt-O bond strength with the decrease of the Pt crystallite size could also inhibit the reaction.
- 71Dai, K.; Peng, T.; Chen, H.; Liu, J.; Zan, L. Photocatalytic degradation of commercial phoxim over La-doped TiO2 nanoparticles in aqueous suspension. Environ. Sci. Technol. 2009, 43, 1540– 1545, DOI: 10.1021/es802724q71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsl2mug%253D%253D&md5=dfa465b53e9c4f6a4b829475c311c440Photocatalytic degradation of commercial phoxim over lanthanum-doped titanium oxide nanoparticles in aqueous suspensionDai, Ke; Peng, Tianyou; Chen, Hao; Liu, Juan; Zan, LinEnvironmental Science & Technology (2009), 43 (5), 1540-1545CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)Photocatalytic degrdn. of com. phoxim emulsion in aq. suspension was investigated by using La-doped mesoporous TiO2 nanoparticles (m-TiO2) as the photocatalyst under UV irradn. Effects of La-doping level, calcination temp., and addnl. amt. of the photocatalyst on the photocatalytic degrdn. efficiency were investigated in detail. Exptl. results indicate that 20 mg L-1 phoxim in 0.5 g L-1 La/m-TiO2 suspension (the initial pH 4.43) can be decompd. as prolonging the irradn. time. Almost 100 % phoxim was decompd. after 4 h irradn. according to the spectrophotometric analyses, whereas the mineralization rate of phoxim just reached ca. 80 % as checked by ion chromatog. (IC) analyses. The elimination of the org. solvent in the phoxim emulsion as well as the formation and decompn. of some degrdn. intermediates were obsd. by high-performance liq. chromatog.-mass spectroscopy (HPLC-MS). On the basis of the anal. results on the photocatalytic degrdn. intermediates, two possible photocatalytic degrdn. pathways are proposed under the present exptl. conditions, which reveal that both the hydrolysis and adsorption of phoxim under UV light irradn. play important roles during the photocatalytic degrdn. of phoxim.
- 72Shi, Z.-l.; Lai, H.; Yao, S.-h.; Wang, S.-f. Preparation, characterization and photocatalytic activity of lanthanum doped mesoporous titanium dioxide. Chin. J. Chem. Phys. 2012, 25, 96, DOI: 10.1088/1674-0068/25/01/96-10272https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XltFSjtrw%253D&md5=ce645aebd6da53264cc757bf17c056cfPreparation, characterization and photocatalytic activity of lanthanum doped mesoporous titanium dioxideShi, Zhong-liang; Lai, Hong; Yao, Shu-hua; Wang, Shao-fengChinese Journal of Chemical Physics (2012), 25 (1), 96-102CODEN: CJCPA6; ISSN:1674-0068. (Chinese Physical Society)La doped mesoporous TiO2 photocatalysts with different La content were synthesized by template method using tetra-Bu titanate (Ti(OBu)4) as precursor and Pluronic P123 as template. The catalysts were characterized by thermogravimetric DTA, N2 adsorption-desorption measurements, x-ray diffraction, and UV-visible absorption spectroscopy. The effect of La3+ doping concn. from 0.1% to 1% on the photocatalytic activity of mesoporous TiO2 was studied. The characterizations indicated that the photocatalysts possessed a homogeneous pore diam. of ∼10 nm with high surface area of 165 m2/g. XPS measurements indicated the presence of C in the doped samples in addn. to La. Compared with pure mesoporous TiO2, the La-doped samples extended the photoabsorption edge into the visible light region. The results of phenol photodecompn. showed that La-doped mesoporous TiO2 exhibited higher photocatalytic activities than pure mesoporous TiO2 under UV and visible light irradn.
- 73Wang, J.; Tafen, D. N.; Lewis, J. P.; Hong, Z.; Manivannan, A.; Zhi, M.; Li, M.; Wu, N. Origin of photocatalytic activity of nitrogen-doped TiO2 nanobelts. J. Am. Chem. Soc. 2009, 131, 12290– 12297, DOI: 10.1021/ja903781h73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXpsFyis7w%253D&md5=f508306db56e92c53ae6d77de52eb089Origin of Photocatalytic Activity of Nitrogen-Doped TiO2 NanobeltsWang, Jin; Tafen, De Nyago; Lewis, James P.; Hong, Zhanglian; Manivannan, Ayyakkannu; Zhi, Mingjia; Li, Ming; Wu, NianqiangJournal of the American Chemical Society (2009), 131 (34), 12290-12297CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Expts. combined with the d. functional theory (DFT) calcn. have been performed to understand the underlying photocatalysis mechanism of the nitrogen-doped titania nanobelts. Nitrogen-doped anatase titania nanobelts are prepd. via hydrothermal processing and subsequent heat treatment in NH3. Both the nitrogen content and the oxygen vacancy concn. increase with increasing the NH3 treatment temp. Nitrogen doping leads to an add-on shoulder on the edge of the valence band, the localized N 2p levels above the valence band max., and the 3d states of Ti3+ below the conduction band, which is confirmed by DFT calcn. and XPS measurement. Extension of the light absorption from the UV region to the visible-light region arises from the N 2p levels near the valence band and from the color centers induced by the oxygen vacancies and the Ti3+ species. Nitrogen doping allows visible-light-responsive photocatalytic activity but lowers UV-light-responsive photocatalytic activity. The visible-light photocatalytic activity originates from the N 2p levels near the valence band. The oxygen vacancies and the assocd. Ti3+ species act as the recombination centers for the photoinduced electrons and holes. They reduce the photocatalytic activity although they contribute to the visible light absorbance.
- 74Kumar, M. P.; Jagannathan, R.; Ravichandran, S. Photoelectrochemical system for unassisted high-efficiency water-splitting reactions using N-doped TiO2 nanotubes. Energy Fuels 2020, 34, 9030– 9036, DOI: 10.1021/acs.energyfuels.0c0063474https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVWisrfP&md5=99d4ee35bf9320db5dffabac09eeb71ePhotoelectrochemical System for Unassisted High-Efficiency Water-Splitting Reactions Using N-Doped TiO2 NanotubesKumar, M. Praveen; Jagannathan, R.; Ravichandran, S.Energy & Fuels (2020), 34 (7), 9030-9036CODEN: ENFUEM; ISSN:0887-0624. (American Chemical Society)In this study, we report a facile one-step synthesis of porous and defect-rich nitrogen (N)-doped TiO2 nanotubes by the electrochem. anodization process with in situ N-doping on TiO2 nanotubes using nitrogen gas as a nitrogen source. N-doped TiO2 exhibits enhanced visible-light photocatalytic activity toward the photoelectrochem. water-splitting reaction and high stability due to nitrogen doping and band-gap narrowing. Nitrogen-doped nanotubes exhibit unique and efficient photoelectrochem. cell (PEC) water-splitting activity for H2 generation in aq. electrolytes with a pH gradient. The nitrogen doping and the concurrent defects increase the charge d., which can effectively tune the band gap toward the visible light region, hindering the electron-hole recombination process compared to that in bare TiO2 nanotubes. The PEC has been assembled with chem. (pH) bias (unassisted) by the imposition of electrolytes of different pH's, resulting in a pH gradient between the photoanode and the metal cathode. The pH-biased photoelectrochem. cell has been constructed with 1 M NaOH on the photoanode side and 1 M H2SO4 on the cathode side. The PEC of N-doped TiO2 nanotubes exhibits an open circuit potential of 1.3 V with a photocurrent d. of 0.76 mA/cm2 (at 0.5 V) and solar-to-hydrogen (STH) efficiency of 0.5% in an outdoor sunlight measurement. The photoelectrode exhibits a long-term stability of 120 h in an outdoor measurement.
- 75Asahi, R.; Morikawa, T.; Ohwaki, T.; Aoki, K.; Taga, Y. Visible-light photocatalysis in nitrogen-doped titanium oxides. Science 2001, 293, 269– 271, DOI: 10.1126/science.106105175https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXlt1yitbc%253D&md5=db2b823b547b5c3bb17ab314d215660aVisible-light photocatalysis in nitrogen-doped titanium oxidesAsahi, R.; Morikawa, T.; Ohwaki, T.; Aoki, K.; Taga, Y.Science (Washington, DC, United States) (2001), 293 (5528), 269-271CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)To use solar irradn. or interior lighting efficiently, the authors sought a photocatalyst with high reactivity under visible tight. Films and powders of TiO2-xNx have revealed an improvement over titanium dioxide (TiO2) under visible light (wavelength < 500 nm) in optical absorption and photocatalytic activity such as photodegrdns. of Methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface. Nitrogen doped into substitutional sites of TiO2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calcns. and x-ray photoemission spectroscopy.
- 76Gomes, J.; Lincho, J.; Domingues, E.; Quinta-Ferreira, R. M.; Martins, R. C. N–TiO2 photocatalysts: A review of their characteristics and capacity for emerging contaminants removal. Water 2019, 11, 373, DOI: 10.3390/w1102037376https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXitlelsr3M&md5=f661aae2427a893eb11183f89942a2bdN-TiO2 photocatalysts: a review of their characteristics and capacity for emerging contaminants removalGomes, Joao; Lincho, Joao; Domingues, Eva; Quinta-Ferreidra, Rosa M.; Martins, Rui C.Water (Basel, Switzerland) (2019), 11 (2), 373CODEN: WATEGH; ISSN:2073-4441. (MDPI AG)Titanium dioxide is the most used photocatalyst in wastewater treatment; its semiconductor capacity allows the indirect prodn. of reactive oxidative species. The main drawback of the application of TiO2 is related to its high band-gap energy. The nonmetal that is most often used as the doping element is nitrogen, which is due to its capacity to reduce the band-gap energy at low prepn. costs. There are multiple and assorted methods of prepn. The main advantages and disadvantages of a wide range of prepn. methods were discussed in this paper. Different sources of N were also analyzed, and their individual impact on the characteristics of N-TiO2 was assessed. The core of this paper was focused on the large spectrum of anal. techniques to detect modifications in the TiO2 structure from the incorporation of N. The effect of N-TiO2 co-doping was also analyzed, as well as the main characteristics that are relevant to the performance of the catalyst, such as its particle size, surface area, quantum size effect, cryst. phases, and the hydrophilicity of the catalyst surface. Powder is the most used form of N-TiO2, but the economic benefits and applications involving continuous reactors were also analyzed with supported N-TiO2. Moreover, the degrdn. of contaminants emerging from water and wastewater using N-TiO2 and co-doped TiO2 was also discussed.
- 77Zaleska, A. Doped-TiO2: a review. Recent Pat. Eng. 2008, 2, 157– 164, DOI: 10.2174/18722120878630628977https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVaqtrjI&md5=f58bc711feafe750f04a9c2e15c59801Doped-TiO2: a reviewZaleska, AdrianaRecent Patents on Engineering (2008), 2 (3), 157-164CODEN: RPEEBL; ISSN:1872-2121. (Bentham Science Publishers Ltd.)A review. Titanium dioxide represents an effective photocatalyst for water and air purifn. and for self-cleaning surfaces. Addnl., it can be used as antibacterial agent because of strong oxidn. activity and superhydrophilicity. TiO2 shows relatively high reactivity and chem. stability under UV light (λ < 387 nm), whose energy exceeds the band gap of 3.3 eV in the anatase cryst. phase. The development of photocatalysts exhibiting high reactivity under visible light (λ > 400 nm) should allow the main part of the solar spectrum, even under poor illumination of interior lighting, to be used. Visible light-activated TiO2 could be prepd. by metal-ion implantation, reducing of TiO2, nonmetal doping or sensitizing of TiO2 with dyes. This paper reviews prepn. methods of doped-TiO2 with metallic and nonmetallic species, including various types of dopants and doping methods currently available. The mechanism of heterogeneous photocatalysis in the presence of TiO2 is also discussed.
- 78Matthews, R. W.; Abdullah, M.; Low, G. K. C. Photocatalytic oxidation for total organic carbon analysis. Anal. Chim. Acta 1990, 233, 171– 179, DOI: 10.1016/S0003-2670(00)83476-578https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3cXlt1Smsbg%253D&md5=567a97f0edc6277ebac745b56d229bfePhotocatalytic oxidation for total organic carbon analysisMatthews, R. W.; Abdullah, M.; Low, G. K. C.Analytica Chimica Acta (1990), 233 (2), 171-9CODEN: ACACAM; ISSN:0003-2670.A method and app. for the detn. of org. C in water are described. Photocatalytic oxidn. of org. matter by near-UV illuminated TiO2 is used to convert org. C to CO2. Atm. O is the oxidant. The the light source is a 20-W black-light fluorescent tube. The CO2 equilibrates between the reaction loop and a cond. detection loop and the recirculated air forms the interface between the 2 loops. The method is suitable for anal. of water contg. 0.1-30 μg/mL org. C and sample vols. of 1-40 mL. Higher concns. can be detd. after appropriate diln. Times for 99% oxidn. of org. solutes to CO2 are ≤10 min..
- 79Liu, Y.; Xie, L.; Li, Y.; Qu, J.; Zheng, J.; Li, X. Photocatalytic Hydrogen Generation Over Lanthanum Doped TiO2 Under UV Light Irradiation. J. Nanosci. Nanotechnol. 2009, 9, 1514– 1517, DOI: 10.1166/jnn.2009.C19179https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXjslSgs7o%253D&md5=685377812ab1e101ef6a13694c0cdb07Photocatalytic hydrogen generation over lanthanum doped TiO2 under UV light irradiationLiu, Y.; Xie, L.; Li, Y.; Qu, J. L.; Zheng, J.; Li, X. G.Journal of Nanoscience and Nanotechnology (2009), 9 (2), 1514-1517CODEN: JNNOAR; ISSN:1533-4880. (American Scientific Publishers)TiO2 nanoparticles doped with different amt. of lanthanum were obtained by sol-gel approach and followed annealing at different temp. The crystal size of TiO2 doped with lanthanum was smaller than that of pure TiO2. Photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 was investigated. The photocatalytic activity of TiO2 doped with lanthanum for water splitting into H2 is higher than that of pure TiO2. It was found that the optimal photocatalyst was TiO2 doped with 2 wt% lanthanum and calcined at 600 °C for 4 h which had hydrogen generation rate 700.6 μmol h-1.
- 80Zhao, Y.; Wang, W.; He, L. The effects of Co/N dopants on the electronic, redox potential, optical, and photocatalytic water-splitting properties of TiO2: First principles calculations. Chem. Phys. Lett. 2017, 685, 108– 113, DOI: 10.1016/j.cplett.2017.07.04680https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXht1CksLvK&md5=318eea5e2bacd156207e71d4ea6220b6The effects of Co/N dopants on the electronic, redox potential, optical, and photocatalytic water-splitting properties of TiO2: First principles calculationsZhao, Yafei; Wang, Wei; He, LiangChemical Physics Letters (2017), 685 (), 108-113CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)The crystal structure, formation energy, electronic and optical properties of undoped, Co, N doped and co-doped TiO2 were investigated by first principles calcns. Considering the potential of water redox reaction of these systems indicate that only N-, Co-1N- and Co-2N co-doped TiO2 meet the requirement of the photosplitting water. Moreover, the optical absorption threshold and absorption area of Co-2N co-doped TiO2 are obviously enlarged compared with the undoped TiO2. Co-2N co-doped TiO2 has the highest light absorption efficiency and hydrogen prodn. efficiency, due to the presence of curved and broad impurity levels that greatly improve the carriers' mobility and sepn.
- 81Eidsvåg, H.; Bentouba, S.; Vajeeston, P.; Yohi, S.; Velauthapillai, D. TiO2 as a Photocatalyst for Water Splitting─An Experimental and Theoretical Review. Molecules 2021, 26, 1687, DOI: 10.3390/molecules26061687There is no corresponding record for this reference.
- 82Shwetharani, R.; Sakar, M.; Chandan, H.; Balakrishna, R. G. Observation of simultaneous photocatalytic degradation and hydrogen evolution on the lanthanum modified TiO2 nanostructures. Mater. Lett. 2018, 218, 262– 265, DOI: 10.1016/j.matlet.2018.02.03182https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXis1arurs%253D&md5=2398a6b043619667ea9fb93078a17afbObservation of simultaneous photocatalytic degradation and hydrogen evolution on the lanthanum modified TiO2 nanostructuresShwetharani, R.; Sakar, M.; Chandan, H. R.; Geetha Balakrishna, R.Materials Letters (2018), 218 (), 262-265CODEN: MLETDJ; ISSN:0167-577X. (Elsevier B.V.)The simultaneous photocatalytic degrdn. of dye-polluted water and hydrogen prodn. has been demonstrated on the lanthanum-modified TiO2 (La-TiO2) nanostructures. The obsd. changes in the X-ray diffraction pattern of La-TiO2 with respect to pristine-TiO2 indicated the incorporation of La into the lattices of TiO2. The surface adsorption anal. and electron microscopy images revealed the enhanced surface area with spherical and rod-like morphol. for TiO2 and La-TiO2 resp. The obsd. red-shift in the absorption spectrum and the estd. band-gap energy indicated that the La-doping sufficiently altered the band-structure of TiO2 to absorb visible light. The calcd. band-edge positions revealed that La doping suitably altered the band-edge potential of TiO2 for the simultaneous degrdn. and hydrogen prodn.
- 83Choi, H.; Khan, S.; Choi, J.; Dinh, D. T. T.; Lee, S. Y.; Paik, U.; Cho, S.-H.; Kim, S. Synergetic control of band gap and structural transformation for optimizing TiO2 photocatalysts. Appl. Catal., B 2017, 210, 513– 521, DOI: 10.1016/j.apcatb.2017.04.02083https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmtV2mu74%253D&md5=209834443a5e3288587889c8ba9fd416Synergetic control of band gap and structural transformation for optimizing TiO2 photocatalystsChoi, Heechae; Khan, Sovann; Choi, Junghyun; Dinh, Duong T. T.; Lee, Seung Yong; Paik, Ungyu; Cho, So-Hye; Kim, SeungchulApplied Catalysis, B: Environmental (2017), 210 (), 513-521CODEN: ACBEE3; ISSN:0926-3373. (Elsevier B.V.)Impurity doping and synthesizing polymorphic particles are the common strategies to improve activity of TiO2 photocatalyst by lowering the band gap and enhancing electron-hole sepn. rate. However, these two approaches have side effects. Doping of impurities make space charge region (SCR) thinner near the surface, which requires smaller sized particles than undoped TiO2 for the optimal performance. Polymorphic TiO2 particles, in which rutile and anatase phases coexist in a particle, are usually large due to energetic unstability of the rutile phase in a fine particle. For this contradiction that one needs small size while the other needs large size, two effects are not easy to be combined. In this study, we suggest a dual-doping strategy to solve the contradictory problem of SCR redn. by donor doping and inevitable size growth in polymorphic particles. We successfully dope W, a band gap narrower, into fine size of polymorphic particles by Sn-codoping, a promoter of the anatase-to-rutile transformation (ART), and demonstrate greatly improved photocatalytic activity. The accelerated ART by Sn-doping could keep the size of polymorph junctioned TiO2 small (∼10 nm) as lower temp. annealing become able to induce the ART. The concept of dual doping with a band gap narrower and an ART promoter provides a way to synthesize highly active photocatalysts by overcoming the drawback from shortened SCR length.
- 84Singh, B.; Mehta, B. R. Relationship between nature of metal-oxide contacts and resistive switching properties of copper oxide thin film based devices. Thin Solid Films 2014, 569, 35– 43, DOI: 10.1016/j.tsf.2014.08.03084https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVOhtbbN&md5=aa46ba56eeff840f31b7658521fd3bf8Relationship between nature of metal-oxide contacts and resistive switching properties of copper oxide thin film based devicesSingh, Bharti; Mehta, B. R.Thin Solid Films (2014), 569 (), 35-43CODEN: THSFAP; ISSN:0040-6090. (Elsevier B.V.)The current-voltage and resistive switching properties of Cu2O and CuO based resistive random access memories in metal-oxide-metal structure with Cu as bottom electrode and different metals (Ti, Ag, Au and Pd) as top electrodes were studied. The observation of resistive switching in Cu2O and its absence in CuO based devices indicates that ohmic nature of top and bottom metal-oxide contacts is favorable for resistive switching behavior. The rectifying metal-oxide contact results in the applied voltage drop at the rectifying contact, resulting in the absence of elec. field induced structural changes which are crucial for occurrence of resistive switching. The values of switching parameters, such as, electroforming, reset, set voltages and also the resistance ratio also depend upon the work function of the electrode materials and nature of metal-oxide interface.
- 85Grätzel, M. Photoelectrochemical cells. Nature 2001, 414, 338– 344, DOI: 10.1038/3510460785https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXovFGitr8%253D&md5=2b0390f22ab99b07caec95b79454a7ebPhotoelectrochemical cellsGratzel, MichaelNature (London, United Kingdom) (2001), 414 (6861), 338-344CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)A review discussing the historical background, and present status and development prospects of new generation of photoelectrochem. cells.
- 86Malik, A. S.; Liu, T.; Dupuis, M.; Li, R.; Li, C. Water Oxidation on TiO2: A Comparative DFT Study of 1e–, 2e–, and 4e– Processes on Rutile, Anatase, and Brookite. J. Phys. Chem. C 2020, 124, 8094– 8100, DOI: 10.1021/acs.jpcc.9b1145086https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXls12iurg%253D&md5=44265f2bc2e38bc6087f3a4d25e64cd6Water oxidation on TiO2: a comparative DFT study of 1e-, 2e-, and 4e- processes on rutile, anatase, and brookiteMalik, Anum Shahid; Liu, Taifeng; Dupuis, Michel; Li, Rengui; Li, CanJournal of Physical Chemistry C (2020), 124 (15), 8094-8100CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Exptl. studies of the surface reactions of photocatalyzed or photoelectrocatalyzed water oxidn. on rutile, anatase, and brookite TiO2 show significant differences between the three polymorphs. Yet a fundamental understanding of the differences is still lacking. In this work, we carried out a systematic comparative d. functional theory (DFT) investigation of the mechanisms and energetics of water oxidn. on rutile TiO2 (110), anatase TiO2 (101), and brookite TiO2 (210) model surfaces. Our results indicate that for all three phases, the most facile mechanism of water oxidn. proceeds as a two-electron/proton process toward H2O2 formation via surface peroxo O* intermediates. The calcd. overall overpotentials toward H2O2 formation are ~ 0.27, 0.51, and 0.62 V on rutile, anatase, and brookite, resp. The rate-limiting steps toward H2O2 formation are the OH* formation step for all three phases. We studied also the effect of pH. pH alters the binding energies of the reaction intermediates and affects the threshold values for the 1-electron, 2-electron, and 4-electron processes but does not affect the selectivity. Overpotentials for the 4-electron O2 evolution range from 0.8, 1.04, and ~ 1.15 V on rutile, anatase, and brookite, resp., with the same rate-detg. steps as for the 2-electron process. Under photocatalytic conditions of light irradn. corresponding to the redox potential vs. NHE of photogenerated holes in the valence band of the materials (~ 3.0 V for rutile, ~ 3.2 V for anatase, and ~ 3.3 V for brookite), there is enough energy to drive the 4-electron O2 evolution spontaneously as well. Under these conditions, product selectivity (H2O2 vs O2) may require characterizing the reaction kinetics rather than coming out from the thermodn. overpotentials.
- 87Valdés, Á.; Qu, Z. W.; Kroes, G. J.; Rossmeisl, J.; Nørskov, J. K. Oxidation and Photo-Oxidation of Water on TiO2 Surface. J. Phys. Chem. C 2008, 112, 9872– 9879, DOI: 10.1021/jp711929d87https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXmvFOru7w%253D&md5=f27936ce0890b213c057ddcfd8ee382eOxidation and Photo-Oxidation of Water on TiO2 SurfaceValdes, A.; Qu, Z.-W.; Kroes, G.-J.; Rossmeisl, J.; Norskov, J. K.Journal of Physical Chemistry C (2008), 112 (26), 9872-9879CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The oxidn. and photo-oxidn. of water on the rutile TiO2(110) surface is investigated using d. functional theory (DFT) calcns. We investigate the relative stability of different surface terminations of TiO2 interacting with H2O and analyze the overpotential needed for the electrolysis and photoelectrolysis of water. We found that the most difficult step in the splitting of water process is the reaction of a H2O mol. with a vacancy in the surface to form an adsorbed hydroxyl group (OH*). Comparison to expt. shows that the computed overpotential for O2 evolution (0.78 V) is available under the exptl. conditions required for both oxygen and hydrogen evolution.
- 88Jallouli, N.; Elghniji, K.; Trabelsi, H.; Ksibi, M. Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiation. Arabian J. Chem. 2017, 10, S3640– S3645, DOI: 10.1016/j.arabjc.2014.03.01488https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntlartLc%253D&md5=19fdfd22483a77a9fb46b2af91af3528Photocatalytic degradation of paracetamol on TiO2 nanoparticles and TiO2/cellulosic fiber under UV and sunlight irradiationJallouli, Nabil; Elghniji, Kais; Trabelsi, Hassen; Ksibi, MohamedArabian Journal of Chemistry (2017), 10 (Suppl._2), S3640-S3645CODEN: AJCRDR; ISSN:1878-5352. (Elsevier B.V.)In the present study, photocatalytic degrdn. of acetaminophen ((N-(4-hydroxyphe-nyl)acetamide)), an analgesic drug has been investigated in a batch reactor using TiO2 P25 as a photocatalyst in slurry and under UV light. Using TiO2 P25 nanoparticles, much faster photodegrdn. of paracetamol and effective mineralization occurred, more than 90% of 2.65 × 10-4 M paracetamol was degraded under UV irradn. Changes in pH values affected the adsorption and the photodegrdn. of paracetamol. pH 9.0 is found to be the optimum for the photodegrdn. of paracetamol. HPLC detected hydroquinone, benzoquinone, p-nitrophenol, and 1,2,4-trihydroxybenzene during the TiO2-assisted photodegrdn. of paracetamol among which some pathway products are disclosed for the first time. The results showed that TiO2 suspension/UV system is more efficient than the TiO2/cellulosic fiber mode combined to solar light for the photocatalytic degrdn. of paracetamol. Nerveless the immobilization of TiO2 showed many advantages over slurry system because it can enhance adsorption properties while allowing easy sepn. of the photocatalyst from the treated soln. with improved reusable performance.
- 89López Zavala, M. Á.; Jaber Lara, C. R. Degradation of Paracetamol and Its Oxidation Products in Surface Water by Electrochemical Oxidation. Environ. Eng. Sci. 2018, 35, 1248– 1254, DOI: 10.1089/ees.2018.002389https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitVyjur7O&md5=8d94f7d3bf7fbdfc2b4c39f9cd4660e1Degradation of paracetamol and its oxidation products in surface water by electrochemical oxidationLopez Zavala, Miguel Angel; Jaber Lara, Camila ReneeEnvironmental Engineering Science (2018), 35 (11), 1248-1254CODEN: EESCF5; ISSN:1092-8758. (Mary Ann Liebert, Inc.)Paracetamol and its toxic transformation products have been found in surface water, wastewater, and drinking water. Effective methods to degrade these products must be found to reduce their detrimental effects on microorganisms in aquatic systems and minimize the concern on human health. Thus, this study looked into the electrochem. oxidn. of paracetamol and its oxidn. products on surface water, and results were compared with those of paracetamol synthetic soln. oxidn. Degrdn. of paracetamol was conducted using a stainless steel electrode cell, a pH of 3, and d.c. densities of 5.7 mA/cm2 (6 V) and 7.6 mA/cm2 (12 V). For both current densities applied, the pharmaceutical and its oxidn. products obsd. by high-performance liq. chromatog. with diode-array detection (HPLC-DAD) at 254 nm were totally degraded. Faster degrdn. of paracetamol was obsd. at a higher c.d. Indeed, 95% of paracetamol was oxidized in only 15 min at the 7.6 mA/cm2 c.d. In comparison to the paracetamol synthetic soln.'s oxidn., degrdn. of paracetamol was faster in the surface water than the synthetic soln., at 5.7 mA/cm2. Nevertheless, at 7.6 mA/cm2, total degrdn. of paracetamol in surface water was delayed up to 40 min, vs. 7.5 min in the synthetic soln. Three oxidn. products, obsd. by HPLC-DAD at 254 nm, were fully oxidized. In comparison with the paracetamol synthetic soln., degrdn. of the oxidn. products in surface water was faster than in synthetic solns. for both current densities. Furthermore, the 7.6 mA/cm2 c.d. resulted in faster degrdn. of oxidn. products. Results obtained from this work are promising for practical applications because short reaction times and low current densities are needed for degrdn. of paracetamol and its oxidn. products. These densities can be potentially supplied by photovoltaic cells.
- 90Moctezuma, E.; Leyva, E.; Aguilar, C. A.; Luna, R. A.; Montalvo, C. Photocatalytic degradation of paracetamol: Intermediates and total reaction mechanism. J. Hazard. Mater. 2012, 243, 130– 138, DOI: 10.1016/j.jhazmat.2012.10.01090https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsF2ru7%252FI&md5=54ac0825972b5fd36fc01e3f7c3aa727Photocatalytic degradation of paracetamol: Intermediates and total reaction mechanismMoctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A.; Luna, Raul A.; Montalvo, CarlosJournal of Hazardous Materials (2012), 243 (), 130-138CODEN: JHMAD9; ISSN:0304-3894. (Elsevier B.V.)The advanced oxidn. of paracetamol (PAM) promoted by TiO2/UV system in aq. medium was studied. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidn. of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixts. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the arom. amide present in PAM and subsequent formation of several arom. intermediate compds. such as p-aminophenol and p-nitrophenol. These arom. compds. were eventually converted into trans-unsatd. carboxylic acids. Based on these exptl. results, an alternative deacylation mechanism for the photocatalytic oxidn. of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to study oxidative mechanisms of pharmaceuticals.
- 91Xiong, Z.; Ma, J.; Ng, W. J.; Waite, T. D.; Zhao, X. Silver-modified mesoporous TiO2 photocatalyst for water purification. Water Res. 2011, 45, 2095– 2103, DOI: 10.1016/j.watres.2010.12.01991https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXitFaqurg%253D&md5=1337639a5250674d4251a2cb8f8d7b9eSilver-modified mesoporous TiO2 photocatalyst for water purificationXiong, Zhigang; Ma, Jizhen; Ng, Wun Jern; Waite, T. David; Zhao, X. S.Water Research (2011), 45 (5), 2095-2103CODEN: WATRAG; ISSN:0043-1354. (Elsevier B.V.)Mesoporous anatase (TiO2) was modified with silver (Ag) nanoparticles using a photoredn. method. Performance of the resulting TiO2-Ag nanocomposites for water purifn. was evaluated using degrdn. of Rhodamine B (RhB) and disinfection of Escherichia coli (E. coli) under UV irradn. The composites with different Ag loadings were characterized using phys. adsorption of nitrogen, X-ray diffraction, XPS and UV-Visible diffuse reflectance spectroscopic techniques. The results showed that metallic Ag nanoparticles were firmly immobilized on the TiO2 surface, which improved electron-hole sepn. by forming the Schottky barrier at the TiO2-Ag interface. Photocatalytic degrdn. of RhB and inactivation of E. coli effectively occurred in an analogical trend. The deposited Ag slightly decreased adsorption of target pollutants, but greatly increased adsorption of mol. oxygen with the latter enhancing prodn. of reactive oxygen species (ROSs) with concomitant increase in contaminant photodegrdn. The optimal Ag loadings for RhB degrdn. and E. coli disinfection were 0.25 wt% and 2.0 wt%, resp. The composite photocatalysts were stable and could be used repeatedly under UV irradn.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.2c06657.
Photography of TiO2 and Ag/TiO2 photocatalysts, TEM images, Raman spectra, optical bandgap results, BET results, and UPS results (PDF)
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