Electrochemical Properties of Biobased Carbon Aerogels Decorated with Graphene Dots Synthesized from BiocharClick to copy article linkArticle link copied!
- Bony ThomasBony ThomasDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenMore by Bony Thomas
- Gejo GeorgeGejo GeorgeDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenMore by Gejo George
- Anton LandströmAnton LandströmDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenMore by Anton Landström
- Isabella ConcinaIsabella ConcinaDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenMore by Isabella Concina
- Shiyu GengShiyu GengDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenMore by Shiyu Geng
- Alberto VomieroAlberto VomieroDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenDepartment of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Via Torino 155, 30172 Venezia Mestre, ItalyMore by Alberto Vomiero
- Mohini SainMohini SainDivision of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenDepartment of Mechanical & Industrial Engineering (MIE), University of Toronto, Toronto, Ontario M5S 3G8, CanadaMore by Mohini Sain
- Kristiina Oksman*Kristiina Oksman*Email: [email protected]. Tel: +46 70 358 5371.Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, SwedenDepartment of Mechanical & Industrial Engineering (MIE), University of Toronto, Toronto, Ontario M5S 3G8, CanadaMore by Kristiina Oksman
Abstract
Carbon aerogels prepared from low-cost renewable resources are promising electrode materials for future energy storage applications. However, their electrochemical properties must be significantly improved to match the commercially used high-carbon petroleum products. This paper presents a facile method for the green synthesis of carbon aerogels (CAs) from lignocellulosic materials and graphene dots (GDs) from commercially available biochar. The produced carbon aerogels exhibited a hierarchical porous structure, which facilitates energy storage by forming an electrical double-layer capacitance. Surprisingly, the electrochemical analyses of the GD-doped carbon aerogels revealed that in comparison to pristine carbon aerogels, the surface doping of GDs enhanced the electrochemical performance of carbon aerogels, which can be attributed to the combined effect from both double-layer capacitance and pseudocapacitance. Herein, we designed and demonstrated the efficacy of a supercapacitor device using our green carbon electrode as a sustainable option. These green carbon aerogels have opened a window for their practical use in designing sustainable energy storage devices.
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License Summary*
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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
Materials
Preparation of Carbon Aerogels
Figure 1
Figure 1. Schematic representation of the preparation steps for GD-doped carbon aerogel. (a) Preparation of carbon aerogel from lignin/CNF suspension. (b) Synthesis of GDs from biochar using oxidative acid treatment involving 3:1 concentration of H2SO4/HNO3; the reaction mixture was refluxed for 6 h at 90 °C. (c) Surface doping of prepared carbon aerogels using GDs synthesized from biochar.
Preparation of Graphene Dots (GDs) from Wood Biochar
Preparation of Graphene Dots Surface-Doped Carbon Aerogels
UV–Visible and Photoluminescence (PL) Spectroscopy
Raman Spectroscopy
X-ray Diffractometry (XRD)
Thermogravimetric Analysis (TA)
Fourier Transform Infrared Spectroscopy
Atomic Force Microscopy (AFM)
Transmission Electron Microscopy (TEM)
Brunauer–Emmett–Teller (BET) Surface Area Analysis
Field Emission Scanning Electron Microscopy (FE-SEM)
Electrochemical Measurements



Results and Discussion
Figure 2
Figure 2. (a) UV–visible spectrum. (b) Photoluminescence (PL) spectra at different excitation wavelengths, showing the optical properties of the produced GDs in an aqueous medium (0.01 wt %). (c) Atomic force microscopic image of GDs. (d) TEM image showing graphene particles with an ordered carbon structure and a size range of 5–15 nm.
Figure 3
Figure 3. (a) FTIR spectrum of GDs exhibiting numerous surface functional groups. (b) Thermogravimetric analysis of GDs compared to the biochar precursor showing a higher weight loss of GDs owing to the decomposition of carboxylic acid groups. (c) Thermogravimetric analysis of KL and CNF. (d) Raman spectra of biochar precursor, GDs prepared from biochar, and carbon aerogel KLCA60. (e) X-ray diffractometry of the GDs and KLCA60.
Effect of GDs When Incorporated into Carbon Aerogel Based Supercapacitor Electrodes
Figure 4
Figure 4. Microstructure of the prepared materials. (a) and (e) Longitudinal views of KLCA60 and GD-doped KLCA60; magnified images of the longitudinal sections showing the surface texture of both are shown in (b) and (f). Cross-sectional views of KLCA60 and GD-doped KLCA60 are shown in (c) and (g), and the respective high magnification images are shown in (d) and (h).
Figure 5
Figure 5. (a) Solid-state photoluminescence (PL) spectrum of KLCA60 doped with GDs at 315 nm excitation wavelength. (b) Nitrogen adsorption isotherms of KLCA60 and GD-incorporated KLCA60.
sample | BET surface area (m2 g–1) | micropore area (m2 g–1) | pore volume (cm3 g–1) | avg. pore diam. (nm) |
---|---|---|---|---|
KLCA60 | 436 | 223 | 0.254 | 2.33 |
KLCA60 with GDs | 503 | 436 | 0.222 | 1.77 |
Figure 6
Figure 6. (a) and (b) CV curves of supercapacitors composed of KLCA60 and GD-doped KLCA60 at different scan rates. (c) and (d) GCD curves of KLCA60 and GD-doped KLCA60 at different current densities.
Figure 7
Figure 7. Results from the electrochemical analysis. (a) Specific capacitances for KLCA60 at different current densities and (b) specific capacitances of GD-doped KLCA60 at different current densities obtained from GCD analysis. Capacitance contribution calculation using Trasatti method: (c) plot of the reciprocal of the gravimetric capacitance (C–1) against the square root of the scan rate (ν0.5). (d) Plot of C against the reciprocal of the square root of the scan rate (ν–0.5). (e) Nyquist plots obtained from EIS measurements and (f) Ragone plots of the carbon aerogels and GD-incorporated carbon aerogels.
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsaelm.1c00487.
(a) GD dispersion in normal light and 365 nm UV light; (b) height profile of GDs from AFM; (c) size distribution histogram of GDs based on AFM image (Figure S1); results from elemental analysis, EDX spectra of (a) pristine KLCA60 and (b) GD-doped KLCA60 (Figure S2); electrochemical parameters of carbon aerogels and GD-doped carbon aerogels based on cyclic voltammetry (CV) curves (Table S1); electrochemical properties of carbon aerogels and GDs-incorporated carbon aerogels based on galvanostatic charge–discharge (GCD) curves (Table S2); (a) schematic representation of supercapacitor (SC) assembly; (b) equivalent circuit for electrode interface fitted using ZView software showing equivalent series resistance (RESR), double-layer capacitance (CEDL), charge-transfer resistance (RCT), constant phase element (CPE) representing pseudocapacitance along with faradaic resistance (RF); (c) experimental and fitted Nyquist plots; and (d) experimental and fitted |Z| vs frequency plots for the supercapacitor demonstrating good fitting of equivalent circuit with SC (Figure S3); EIS parameters obtained after fitting the equivalent circuit using ZView (Table S3); capacitance retention for the GD-doped KLCA60 electrode after 3000 cycles in the cyclic stability measurements using three-electrode system at 3 A g–1; inset showing the charge–discharge cycles for 2990–3000 cycles; Trasatti method (Figure S4) (PDF)
Terms & Conditions
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Acknowledgments
The authors are grateful for the funding provided by the Bio4Energy National Strategic Research Program (Project name: Carbonization of biomass to high-quality renewable carbon materials for CO2 capture and energy storage). The authors are also thankful for the Grelectronics Project financed by Business Finland, Vetenskapsrådet VR for financing (Carbon Lignin 2017-04240), and the Kempe Foundation for financing the research infrastructure at LTU. Dr. Rasoul Esmaeely and the University of Oulu Nanocenter are acknowledged for the TEM analysis.
References
This article references 46 other publications.
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- 7Ganganboina, A. B.; Dutta Chowdhury, A.; Doong, R. A. New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance Supercapacitors. ACS Sustainable Chem. Eng. 2017, 5, 4930– 4940, DOI: 10.1021/acssuschemeng.7b00329Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmvVGntbs%253D&md5=d3af236df4c136037866ae80e2190820New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance SupercapacitorsGanganboina, Akhilesh Babu; Dutta Chowdhury, Ankan; Doong, Ruey-anACS Sustainable Chemistry & Engineering (2017), 5 (6), 4930-4940CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Graphene quantum dots (GQDs) are a newly developed graphene family with good elec. cond. and high theor. capacitance, while halloysite nanotubes (HNTs) are naturally occurring layered mineral materials contg. high active sites for energy storage support. The combination of HNTs and GQDs can offer a new strategy on the fabrication of eco-friendly electrode materials for high performance supercapacitor applications. Herein, an environmentally friendly GQD-HNT nanocomposite is fabricated in the presence of (3-aminopropyl)-triethoxysilane to provide increased charge storage sites as well as to allow for the fast charge transport for supercapacitor application. Morphol. and surface anal. results show that 5-10 nm GQDs are homogeneously distributed on the surface of APTES-coated HNTs via amide linkage. This new and novel layered nanocomposite can provide accessible electroactive sites and low resistance to accelerate the electrons and electrolyte ion transport, resulting in excellent specific capacitance and high energy d. The specific capacitances of 363-216 F/g at current densities of 0.5-20 A/g are obtained. In addn., the GQD-HNTs exhibit excellent energy d. of 30-50 Wh/kg. Results obtained in this study clearly demonstrate the feasibility of using GQD-HNTs as alternative energy storage materials with increased charge storage sites and fast charge transport for high energy d. supercapacitor applications.
- 8Zhu, Y.; Ji, X.; Pan, C.; Sun, Q.; Song, W.; Fang, L.; Chen, Q.; Banks, C. E. A Carbon Quantum Dot Decorated RuO 2 Network: Outstanding Supercapacitances under Ultrafast Charge and Discharge. Energy Environ. Sci. 2013, 6, 3665– 3675, DOI: 10.1039/c3ee41776jGoogle Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvVajtbbI&md5=e8bf5427ebe94121043372469bd6234fA carbon quantum dot decorated RuO2 network: outstanding supercapacitances under ultrafast charge and dischargeZhu, Yirong; Ji, Xiaobo; Pan, Chenchi; Sun, Qingqing; Song, Weixin; Fang, Laibing; Chen, Qiyuan; Banks, Craig E.Energy & Environmental Science (2013), 6 (12), 3665-3675CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)Carbon quantum dots (CQDs) due to their unique properties have recently attracted extensive attention from researchers in many fields. In the present work, a new application in the form of a CQD-based hybrid as an excellent electrode material for supercapacitors is reported for the first time. The CQDs are fabricated by a facile chem. oxidn. method following which they are thermally reduced, and further decorated with RuO2 to obtain the composites. The hybrid exhibits a specific capacitance of 460 F g-1 at an ultrahigh c.d. of 50 A g-1 (41.9 wt% Ru loading), and excellent rate capability (88.6, 84.2, and 77.4% of capacity retention rate at 10, 20, and 50 A g-1 compared with 1 A g-1, resp.). Surprisingly, the hybrid shows exceptional cycling stability with 96.9% capacity retention over 5000 cycles at 5 A g-1. Such remarkable electrochem. performances can be primarily ascribed to the significantly enhanced utilization of RuO2 achieved by the efficient dispersion of tiny reduced CQDs and the formation of a CQD-based hybrid network structure that can facilitate the fast charge transport and ionic motion during the charge-discharge process. Addnl., the contact resistance at the interface between active materials and current collectors is concluded to be a key factor in detg. the performance of the hybrid. These results above demonstrate the great potential of CQD-based hybrid materials in the development of high-performance electrode materials for supercapacitors.
- 9Jian, X.; Li, J. G.; Yang, H. M.; Cao, L. L.; Zhang, E. H.; Liang, Z. H. Carbon Quantum Dots Reinforced Polypyrrole Nanowire via Electrostatic Self-Assembly Strategy for High-Performance Supercapacitors. Carbon 2017, 114, 533– 543, DOI: 10.1016/j.carbon.2016.12.033Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitFKrtbrN&md5=556ec3f563c5a94f73d35e6d2a69a8d6Carbon quantum dots reinforced polypyrrole nanowire via electrostatic self-assembly strategy for high-performance supercapacitorsJian, Xuan; Li, Jia-gang; Yang, Hui-min; Cao, Le-le; Zhang, Er-hui; Liang, Zhen-haiCarbon (2017), 114 (), 533-543CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)Carbon quantum dots (CQDs) reinforced polypyrrole nanowire (PPy-NW) was constructed via electrostatic self-assembly strategy. The as-made CQDs/PPy-NW composite demonstrated superior electrochem. properties benefited from a dotted line structure with large specific area, more active sites and outstanding electronic cond. As the results, the CQDs/PPy-NW composite electrode displayed a specific capacitance of 306 F g-1 at a c.d. of 0.5 A g-1 and retained 66.8% capacitance when the c.d. increased by 80 times (from 0.5 to 40 A g-1). In addn., the as-fabricated sym. supercapacitor was able to offer a large areal capacitance (248.5 mF cm-2 at 0.2 mA cm-2) and good rate capability, the supercapacitor still retained good cycling stability even at a high c.d. of 5 mA cm-2 (85.2% capacitance retention after 5000 cycles). In conclusion, the good electrochem. properties suggest a great potential of the CQDs/PPy-NW in the development of high-performance supercapacitor electrode materials.
- 10Ahmed, S.; Ahmed, A.; Rafat, M. Supercapacitor Performance of Activated Carbon Derived from Rotten Carrot in Aqueous, Organic and Ionic Liquid Based Electrolytes. J. Saudi Chem. Soc. 2018, 22, 993– 1002, DOI: 10.1016/j.jscs.2018.03.002Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVensbfP&md5=1fb18bd60a879065b4cca961bce29f7dSupercapacitor performance of activated carbon derived from rotten carrot in aqueous, organic and ionic liquid based electrolytesAhmed, Sultan; Ahmed, Ahsan; Rafat, M.Journal of Saudi Chemical Society (2018), 22 (8), 993-1002CODEN: JSCSFO; ISSN:2212-4640. (Elsevier B.V.)In this work, we report the synthesis of porous activated carbon (AC). AC was derived from rotten carrot, at different values of activating temp. under inert atm., employing chem. activation method and ZnCl2 as activation agent. On the basis of results obsd. by surface area and pore size anal., effect of activation temp. on synthesized AC was detd. Other material properties such as morphol., thermal stability, vibrational response, and crystal structure of prepd. AC were studied using std. techniques of material characterization. Further, the electrochem. performance of synthesized AC was studied as an electrode, in aq., org. and ionic liq. based electrolyte. It was found that the synthesized AC based electrode exhibits highest specific capacitance (135.5 F g-1 at 10 mHz) in aq. electrolyte and highest specific energy (29.1 Wh kg-1 at 2.2 A g-1) and specific power (142.5 kW kg-1 at 2.2 A g-1) in ionic liq. based electrolyte. This shows the suitability of synthesized material for use in energy storage applications.
- 11Genc, R.; Alas, M. O.; Harputlu, E.; Repp, S.; Kremer, N.; Castellano, M.; Colak, S. G.; Ocakoglu, K.; Erdem, E. High-Capacitance Hybrid Supercapacitor Based on Multi-Colored Fluorescent Carbon-Dots. Sci. Rep. 2017, 7, 11222 DOI: 10.1038/s41598-017-11347-1Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cbmvFelsQ%253D%253D&md5=ec24ad22691ff88a47cc1bc68bc700f8High-Capacitance Hybrid Supercapacitor Based on Multi-Colored Fluorescent Carbon-DotsGenc Rukan; Alas Melis Ozge; Genc Rukan; Harputlu Ersan; Colak Suleyman Gokhan; Ocakoglu Kasim; Repp Sergej; Kremer Nora; Castellano Mike; Erdem Emre; Ocakoglu KasimScientific reports (2017), 7 (1), 11222 ISSN:.Multi-colored, water soluble fluorescent carbon nanodots (C-Dots) with quantum yield changing from 4.6 to 18.3% were synthesized in multi-gram using dated cola beverage through a simple thermal synthesis method and implemented as conductive and ion donating supercapacitor component. Various properties of C-Dots, including size, crystal structure, morphology and surface properties along with their Raman and electron paramagnetic resonance spectra were analyzed and compared by means of their fluorescence and electronic properties. α-Manganese Oxide-Polypyrrole (PPy) nanorods decorated with C-Dots were further conducted as anode materials in a supercapacitor. Reduced graphene oxide was used as cathode along with the dicationic bis-imidazolium based ionic liquid in order to enhance the charge transfer and wetting capacity of electrode surfaces. For this purpose, we used octyl-bis(3-methylimidazolium)diiodide (C8H16BImI) synthesized by N-alkylation reaction as liquid ionic membrane electrolyte. Paramagnetic resonance and impedance spectroscopy have been undertaken in order to understand the origin of the performance of hybrid capacitor in more depth. In particular, we obtained high capacitance value (C = 17.3 μF/cm(2)) which is exceptionally related not only the quality of synthesis but also the choice of electrode and electrolyte materials. Moreover, each component used in the construction of the hybrid supercapacitor is also played a key role to achieve high capacitance value.
- 12Kai, D.; Tan, M. J.; Chee, P. L.; Chua, Y. K.; Yap, Y. L.; Loh, X. J. Towards Lignin-Based Functional Materials in a Sustainable World. Green Chem. 2016, 18, 1175– 1200, DOI: 10.1039/C5GC02616DGoogle Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xlt1Ggsw%253D%253D&md5=74dffba3d3a1f6e52aae67d1969c514aTowards lignin-based functional materials in a sustainable worldKai, Dan; Tan, Mein Jin; Chee, Pei Lin; Chua, Yun Khim; Yap, Yong Liang; Loh, Xian JunGreen Chemistry (2016), 18 (5), 1175-1200CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)In light of the incessant consumption of raw materials in the world today, the search for sustainable resources is ever pressing. Lignin, the second most naturally abundant biomass, which makes up 15% to 35% of the cell walls of terrestrial plants, has always been treated as waste and used in low-value applications such as heat and electricity generation. However, its abundance in nature could potentially solve the problem of the rapidly depleting resources if it was successfully translated into a renewable resource or valorized to higher value materials. Advanced lignin modification chem. has generated a no. of functional lignin-based polymers, which integrate both the intrinsic features of lignin and addnl. properties of the grafted polymers. These modified lignin and its copolymers display better miscibility with other polymeric matrixes, leading to improved performance for these lignin/polymer composites. This review summarizes the progress in using such biopolymers as reinforcement fillers, antioxidants, UV adsorbents, antimicrobial agents, carbon precursors and biomaterials for tissue engineering and gene therapy. Recent developments in lignin-based smart materials are discussed as well.
- 13Bajwa, D. S.; Pourhashem, G.; Ullah, A. H.; Bajwa, S. G. A Concise Review of Current Lignin Production, Applications, Products and Their Environment Impact. Ind. Crops Prod. 2019, 139, 111526 DOI: 10.1016/j.indcrop.2019.111526Google Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsVCgsbjK&md5=6faa7016346504cd9562d4cdacbbfe34A concise review of current lignin production, applications, products and their environment impactBajwa, D. S.; Pourhashem, G.; Ullah, A. H.; Bajwa, S. G.Industrial Crops and Products (2019), 139 (), 111526CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)A review. Lignin is the second most abundant natural material on the earth. Com., it is generated as a waste product from the paper and ethanol prodn. The worldwide prodn. of lignin is approx. 100 million tonnes/yr valued at USD 732.7 million in 2015. It is expected to reach $913.1 million by 2025 with compd. annual growth rate (CAGR) of 2.2%. Two principal categories of lignin are ligno-sulfonate (∼88%) and kraft lignins (∼9%), however a new category organosolv (∼2%) is now gaining popularity due to the prodn. of second generation biofuels (bioethanol prodn.). The organosolv lignin segment is expected to experience the highest growth over the coming years, at an estd. CAGR of over 5% from 2016 to 2025. Chem. lignin is a polyarom. macromol. The complexity and richness of its functional groups makes it attractive for converting into a variety of value added products like high performance carbon fiber, bio-oil, vanillin, and phenolic resin to name a few. Over the years lignin has been predominantly burnt as fuel for heat and power. Less than 2% of the available lignin was sold, primarily in the formulation of dispersants, adhesives and surfactants. However, in the last decade lignin-based research and new product development has picked significant momentum due to the bio-refinery concept as aging pulp and paper mills need to diversify their products portfolio to maintain their vitality. The emerging biofuel/bioenergy technologies are working to develop value-added co-products from lignin and bio-oil as a means of making the processes more cost effective. There is a resurgence in the demand for lignin for use in binders, adhesives, bioplastics, concrete admixts. and biomedical applications. Effective "upstream" and "downstream" valorization techniques are facilitating fine tuning of lignin as a building block for high value chems. Other market dynamics driving lignin use are stringent regulations for dust control, demand for high quality concrete admixts. and dispersants, and carbon rich products (activated carbon, carbon filer, resins, etc.). To further accelerate development of lignin based products consumer awareness and gap between research and development and consumer products need to be reduced.
- 14Geng, S.; Wei, J.; Jonasson, S.; Hedlund, J.; Oksman, K. Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage. ACS Appl. Mater. Interfaces 2020, 12, 7432– 7441, DOI: 10.1021/acsami.9b19955Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtlWhurk%253D&md5=a1615e53c2f26c21293e7c17482f2beeMultifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy StorageGeng, Shiyu; Wei, Jiayuan; Jonasson, Simon; Hedlund, Jonas; Oksman, KristiinaACS Applied Materials & Interfaces (2020), 12 (6), 7432-7441CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)In current times, CO2 capture and lightwt. energy storage are receiving significant attention and will be vital functions in next-generation materials. Porous carbonaceous materials have great potential in these areas, whereas most of the developed carbon materials still have significant limitations, such as nonrenewable resources, complex and costly processing, or the absence of tailorable structure. In this study, a new strategy is developed for using the currently underutilized lignin and cellulose nanofibers, which can be extd. from renewable resources to produce high-performance multifunctional carbon aerogels with a tailorable, anisotropic pore structure. Both the macro- and microstructure of the carbon aerogels can be simultaneously controlled by carefully tuning the wt. ratio of lignin to cellulose nanofibers in the precursors, which considerably influences their final porosity and surface area. The designed carbon aerogels demonstrate excellent performance in both CO2 capture and capacitive energy storage, and the best results exhibit a CO2 adsorption capacity of 5.23 mmol g-1 at 273 K and 100 kPa and a specific elec. double-layer capacitance of 124 F g-1 at a c.d. of 0.2 A g-1, indicating that they have great future potential in the relevant applications.
- 15Thomas, B.; Geng, S.; Sain, M.; Oksman, K. Hetero-Porous, High-Surface Area Green Carbon Aerogels for the next-Generation Energy Storage Applications. Nanomaterials 2021, 11, 653 DOI: 10.3390/nano11030653Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVOjtLnF&md5=cba2dbd45cfd99658af4cae5f55a866aHetero-porous, high-surface area green carbon aerogels for the next-generation energy storage applicationsThomas, Bony; Geng, Shiyu; Sain, Mohini; Oksman, KristiinaNanomaterials (2021), 11 (3), 653CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)Various carbon materials have been developed for energy storage applications to address the increasing energy demand in the world. However, the environmentally friendly, renewable, and nontoxic bio-based carbon resources have not been extensively investigated towards high performance energy storage materials. Here, the authors report an anisotropic, hetero-porous, high-surface area carbon aerogel prepd. from renewable resources achieving an excellent elec. double-layer capacitance. Two different green, abundant, and carbon-rich lignins which can be extd. from various biomasses, have been selected as raw materials, i.e., kraft and soda lignins, resulting in clearly distinct phys., structural as well as electrochem. characteristics of the carbon aerogels after carbonization. The obtained green carbon aerogel based on kraft lignin not only demonstrates a competitive specific capacitance as high as 163 F g-1 and energy d. of 5.67 Wh kg-1 at a power d. of 50 W kg-1 when assembled as a two-electrode sym. supercapacitor, but also shows outstanding compressive mech. properties. This reveals the great potential of the carbon aerogels developed in this study for the next-generation energy storage applications requiring green and renewable resources, lightwt., robust storage ability, and reliable mech. integrity.
- 16Liu, C.; Yu, Z.; Neff, D.; Zhamu, A.; Jang, B. Z. Graphene-Based Supercapacitor with an Ultrahigh Energy Density. Nano Lett. 2010, 10, 4863– 4868, DOI: 10.1021/nl102661qGoogle Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtl2jtbjF&md5=8986081b4c509727a1aec3ccf003f76bGraphene-Based Supercapacitor with an Ultrahigh Energy DensityLiu, Chenguang; Yu, Zhenning; Neff, David; Zhamu, Aruna; Jang, Bor Z.Nano Letters (2010), 10 (12), 4863-4868CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)A supercapacitor with graphene-based electrodes was found to exhibit a specific energy d. of 85.6 Wh/kg at room temp. and 136 Wh/kg at 80° (all based on the total electrode wt.), measured at a c.d. of 1 A/g. These energy d. values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full use of the highest intrinsic surface capacitance and sp. surface area of single-layer graphene by prepg. curved graphene sheets that will not restack face-to-face. The curved morphol. enables the formation of mesopores accessible to and wettable by environmentally benign ionic liqs. capable of operating at a voltage >4 V.
- 17Li, Z.; Qin, P.; Wang, L.; Yang, C.; Li, Y.; Chen, Z.; Pan, D.; Wu, M. Amine-Enriched Graphene Quantum Dots for High-Pseudocapacitance Supercapacitors. Electrochim. Acta 2016, 208, 260– 266, DOI: 10.1016/j.electacta.2016.05.030Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xot1Knt74%253D&md5=c85ba596a4fc0ecfe052d14b1ff7186fAmine-enriched Graphene Quantum Dots for High-pseudocapacitance SupercapacitorsLi, Zhen; Qin, Ping; Wang, Liang; Yang, Chengshuai; Li, Yanfeng; Chen, Zhiwen; Pan, Dengyu; Wu, MinghongElectrochimica Acta (2016), 208 (), 260-266CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Ltd.)The applications of C-based supercapacitors were limited by their low energy storage d. owing to their limited active storage sites. To overcome this limitation, amine-enriched porous C electrodes were fabricated by the electrostatic fusion of amine-functionalized single-cryst. graphene quantum dots (GQDs) within conductive, vertically ordered TiO2 nanotube arrays as the collectors. The C films deliver ultrahigh specific capacitance (400-595 F g-1) even beyond the theor. upper limit of single-layer graphene by inducing a high concn. of active amine moieties at edge. Sym. GQD supercapacitors in H2SO4 electrolyte offer energy d. up to 21.8 Wh kg-1 and retain 90% of the initial capacitance after 10000 cyclic voltammetry tests. Amine-enriched GQDs can function as a new kind of highly active, soln.-processable, and low-cost pseudocapacitive materials applicable to high-performance supercapacitors.
- 18Yoo, J. J.; Balakrishnan, K.; Huang, J.; Meunier, V.; Sumpter, B. G.; Srivastava, A.; Conway, M.; Mohana Reddy, A. L.; Yu, J.; Vajtai, R.; Ajayan, P. M. Ultrathin Planar Graphene Supercapacitors. Nano Lett. 2011, 11, 1423– 1427, DOI: 10.1021/nl200225jGoogle Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXivFCnurg%253D&md5=f23802077f1d84f7440d041112213f47Ultrathin planar graphene supercapacitorsYoo, Jung Joon; Balakrishnan, Kaushik; Huang, Jingsong; Meunier, Vincent; Sumpter, Bobby G.; Srivastava, Anchal; Conway, Michelle; Reddy, Arava Leela Mohana; Yu, Jin; Vajtai, Robert; Ajayan, Pulickel M.Nano Letters (2011), 11 (4), 1423-1427CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)With the advent of atomically thin and flat layers of conducting materials such as graphene, new designs for thin film energy storage devices with good performance have become possible. Here, we report an "in-plane" fabrication approach for ultrathin supercapacitors based on electrodes comprised of pristine graphene and multilayer reduced graphene oxide. The in-plane design is straightforward to implement and exploits efficiently the surface of each graphene layer for energy storage. The open architecture and the effect of graphene edges enable even the thinnest of devices, made from as grown 1-2 graphene layers, to reach specific capacities up to 80 μFcm-2, while much higher (394 μFcm-2) specific capacities are obsd. multilayer reduced graphene oxide electrodes. The performances of devices with pristine as well as thicker graphene-based structures are examd. using a combination of expts. and model calcns. The demonstrated all solid-state supercapacitors provide a prototype for a broad range of thin-film based energy storage devices.
- 19Abbas, A.; Mariana, L. T.; Phan, A. N. Biomass-Waste Derived Graphene Quantum Dots and Their Applications. Carbon 2018, 140, 77– 99, DOI: 10.1016/j.carbon.2018.08.016Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsF2mu7nJ&md5=325a7fe9c7e771b1663091fb8bff06f4Biomass-waste derived graphene quantum dots and their applicationsAbbas, Aumber; Mariana, Lim Tuti; Phan, Anh N.Carbon (2018), 140 (), 77-99CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)A review. Energy crisis, environmental deterioration, and increasing customer needs have compelled scientists to search facile, low cast, and green routes for the prodn. of novel advanced materials from renewable resources. Among various materials explored, carbon-based nanomaterials, esp. graphene and graphene quantum dots (GQDs), have attracted extensive attention recently owning to their intriguing properties, such as high cond., extensive surface area, good biocompatibility, low toxicity, and long life. This review focuses on the conversion of biomass-waste into GQDs through a no. of facile, low cost, and scalable routes. Factors affecting the phys. and chem. properties of GQDs for numerous promising applications have also been discussed. GQDs have shown promising applications in the field of catalysis, carbon fixation, fuel cells, bio-imaging, drug delivery, and gas sensors. Interestingly, the recent and novel applications of GQDs in the conversion and storage of energy has been discussed here. Finally, the remaining challenges, future perspectives and possible research directions in the field are presented.
- 20Yan, Y.; Gong, J.; Chen, J.; Zeng, Z.; Huang, W.; Pu, K.; Liu, J.; Chen, P. Recent Advances on Graphene Quantum Dots: From Chemistry and Physics to Applications. Adv. Mater. 2019, 31, 1808283 DOI: 10.1002/adma.201808283Google ScholarThere is no corresponding record for this reference.
- 21Li, Y.; Wu, F.; Jin, X.; Xu, H.; Liu, X.; Shi, G. Preparation and Electrochemical Properties of Graphene Quantum Dots/Biomass Activated Carbon Electrodes. Inorg. Chem. Commun. 2020, 112, 107718 DOI: 10.1016/j.inoche.2019.107718Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVSmsr3I&md5=30f6034cf7f97c30f9bbaf6468bf54c5Preparation and electrochemical properties of graphene quantum dots/biomass activated carbon electrodesLi, Ying; Wu, Feifei; Jin, Xuan; Xu, Humin; Liu, Xuefeng; Shi, GangInorganic Chemistry Communications (2020), 112 (), 107718CODEN: ICCOFP; ISSN:1387-7003. (Elsevier B.V.)Graphene quantum dots and biomass activated carbon have enormous potential for electrochem. application, which composites as anode materials for lithium ion battery are rarely reported. Here, the rice husk based activated carbon was modified by graphene quantum dots, exhibiting excellent electrochem. performance as an electrode for lithium ion battery. With the introduction of graphene quantum dots, the charge transfer resistance of the electrode was reduced from 577.7 Ω to 123.9 Ω, and the lithium ion diffusion coeff. was increased by 175 times. Meanwhile, the introduction of graphene quantum dots plays an important role in improving the cycle stability of the battery.
- 22Li, L.; Wu, G.; Yang, G.; Peng, J.; Zhao, J.; Zhu, J. J. Focusing on Luminescent Graphene Quantum Dots: Current Status and Future Perspectives. Nanoscale 2013, 5, 4015– 4039, DOI: 10.1039/c3nr33849eGoogle Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmvFOqsrg%253D&md5=ec24e752dc6e18aacf2d73aaca268db5Focusing on luminescent graphene quantum dots: current status and future perspectivesLi, Lingling; Wu, Gehui; Yang, Guohai; Peng, Juan; Zhao, Jianwei; Zhu, Jun-JieNanoscale (2013), 5 (10), 4015-4039CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A review. To obtain graphene-based fluorescent materials, one of the effective approaches is to convert one-dimensional (1D) graphene to 0D graphene quantum dots (GQDs), yielding an emerging nanolight with extraordinary properties due to their remarkable quantum confinement and edge effects. In this review, the state-of-the-art knowledge of GQDs is presented. The synthetic methods were summarized, with emphasis on the top-down routes which possess the advantages of abundant raw materials, large scale prodn. and simple operation. Optical properties of GQDs are also systematically discussed ranging from the mechanism, the influencing factors to the optical tunability. The current applications are also reviewed, followed by an outlook on their future and potential development, involving the effective synthetic methods, systematic photoluminescent mechanism, bandgap engineering, in addn. to the potential applications in bioimaging, sensors, etc.
- 23Gong, X.; Hu, Q.; Chin Paau, M.; Zhang, Y.; Zhang, L.; Shuang, S.; Dong, C.; Choi, M. M. F. High-Performance Liquid Chromatographic and Mass Spectrometric Analysis of Fluorescent Carbon Nanodots. Talanta 2014, 129, 529– 538, DOI: 10.1016/j.talanta.2014.04.008Google Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlOmu73N&md5=a49e875d2d423b998cff665754b5b9ffHigh-performance liquid chromatographic and mass spectrometric analysis of fluorescent carbon nanodotsGong, Xiaojuan; Hu, Qin; Man, Chin Paau; Zhang, Yan; Zhang, Lei; Shuang, Shaomin; Dong, Chuan; Choi, Martin M. F.Talanta (2014), 129 (), 529-538CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)Amino/hydroxyl-functionalized fluorescent carbon nanodots (C-NanoD) are conveniently synthesized based on hydrothermal carbonization of chitosan at 180° C. Dialysis membranes with small cut-off masses (500-1000 Da) were found useful for removing the side-products and low mol. mass species to purify the C-NanoD product. Herein, reversed-phase high-performance liq. chromatog. (RP-HPLC) has been successfully applied to fractionate the C-NanoD product. The elution order of the C-NanoD species present in the sample follows approx. their core sizes from small to large. The sepd. C-NanoD fractions are collected and characterized by UV absorption spectroscopy, photoluminescence (PL) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and transmission electron microscopy (TEM). All the C-NanoD fractions display a distinctive absorption band at 300 nm, attributing to the n→π* transition of C=O bond. The PL spectra of the fractions display emission peaks at 400-415 nm which are slightly red-shifted with their increase in relative mol. masses. The C-NanoD fractions are fully anatomized by MALDI-TOF MS, displaying their fragmentation mass ion features. The core sizes of some selected C-NanoD are detd. as 1.6, 1.8, 2.5, and 3.1 nm by TEM which are in consistent with their HPLC elution order. The findings highlight the virtues of RP-HPLC to fractionate and reveal the unique characteristics of individual C-NanoD species present in an as-synthesized C-NanoD product which may have potential applications in the fields of bioanal., bioimaging, catalysis, chemosensing, energy storage, and optoelectronics device.
- 24Fringes, S.; Volk, C.; Terrés, B.; Dauber, J.; Engels, S.; Trellenkamp, S.; Stampfer, C. Tunable Capacitive Inter-Dot Coupling in a Bilayer Graphene Double Quantum Dot. Phys. Status Solidi C 2012, 9, 169– 174, DOI: 10.1002/pssc.201100340Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFWrt7c%253D&md5=69960af3185f4ccd676e27afa05ac5e4Tunable capacitive inter-dot coupling in a bilayer graphene double quantum dotFringes, Stefan; Volk, Christian; Terres, Bernat; Dauber, Jan; Engels, Stephan; Trellenkamp, Stefan; Stampfer, ChristophPhysica Status Solidi C: Current Topics in Solid State Physics (2012), 9 (2), 169-174CODEN: PSSCGL; ISSN:1610-1642. (Wiley-Blackwell)We report on a double quantum dot which is formed in a width-modulated etched bilayer graphene nanoribbon. A no. of lateral graphene gates enable us to tune the quantum dot energy levels and the tunneling barriers of the device over a wide energy range. Charge stability diagrams and in particular individual triple point pairs allow to study the tunable capacitive inter-dot coupling energy as well as the spectrum of the electronic excited states on a no. of individual triple points. We ext. a mutual capacitive inter-dot coupling in the range of 2-6 meV and an inter-dot tunnel coupling on the order of 1.5 μeV. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
- 25Feng, J.; Dong, H.; Yu, L.; Dong, L. The Optical and Electronic Properties of Graphene Quantum Dots with Oxygen-Containing Groups: A Density Functional Theory Study. J. Mater. Chem. C 2017, 5, 5984– 5993, DOI: 10.1039/C7TC00631DGoogle Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXot1ejurs%253D&md5=3f10a0062c0fac485bc66c791fa0ea1dThe optical and electronic properties of graphene quantum dots with oxygen-containing groups: a density functional theory studyFeng, Jianguang; Dong, Hongzhou; Yu, Liyan; Dong, LifengJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2017), 5 (24), 5984-5993CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)The effects of 5 types of O-contg. functional groups (-COOH, -COC-, -OH, -CHO, and -OMe) on graphene quantum dots (GQDs) are studied using time-dependent d. functional theory (TD-DFT). Their absorption spectra and HOMO-LUMO gaps are quant. analyzed to reveal the influence of different O-contg. groups including their locations and quantities on the optical properties of GQDs. Compared with those on the edge of the GQD plane, O-contg. groups located on the surface have more evident effects on the optical properties. The calcd. HOMO-LUMO gaps of pristine GQDs and edge-functionalized GQDs with -OH, -COOH, -OMe, -CHO, and -COC- are 2.34, 2.32, 2.31, 2.30, 2.27, and 2.15 eV, resp., whereas the HOMO-LUMO gaps of surface-functionalized GQDs with the groups above are 0.36, 0.32, 0.37, 0.39, and 1.86 eV, resp. The influence of surface and edge functionalization on the HOMO-LUMO gap of GQDs is almost opposite. The absorption process is studied along with excited state anal., which includes the oscillator strengths, natural transition orbitals, and charge difference d. Functionalization on the basal plane greatly changes the distribution of electron d. in surface-functionalized GQDs.
- 26Zhu, C.; Yang, S.; Wang, G.; Mo, R.; He, P.; Sun, J.; Di, Z.; Kang, Z.; Yuan, N.; Ding, J.; Ding, G.; Xie, X. A New Mild, Clean and Highly Efficient Method for the Preparation of Graphene Quantum Dots without by-Products. J. Mater. Chem. B 2015, 3, 6871– 6876, DOI: 10.1039/c5tb01093dGoogle Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1GrsrfI&md5=6b642307a873ec63302e9bbb0f943d77A new mild, clean and highly efficient method for the preparation of graphene quantum dots without by-productsZhu, Chong; Yang, Siwei; Wang, Gang; Mo, Runwei; He, Peng; Sun, Jing; Di, Zengfeng; Kang, Zhenhui; Yuan, Ningyi; Ding, Jianning; Ding, Guqiao; Xie, XiaomingJournal of Materials Chemistry B: Materials for Biology and Medicine (2015), 3 (34), 6871-6876CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)We demonstrated that graphene oxide (GO) can be oxidized and cut into graphene quantum dots (GQDs) by hydroxyl radicals (•OH), which is obtained by the catalytic decompn. of hydrogen peroxide (H2O2) with a tungsten oxide nanowire (W18O49) catalyst. The clean oxidizing agent (H2O2) and the solid catalyst lead to a simple GQD prepg. method without any byproducts. The obtained GQD aq. soln. can be directly applied to fluorescence imaging in vitro without any further purifn. The effect of the W18O49 catalyst on the •OH formation is discussed, and the size of GQDs can be controlled via changing the concn. of hydroxyl radicals.
- 27Zong, J.; Zhu, Y.; Yang, X.; Shen, J.; Li, C. Synthesis of Photoluminescent Carbogenic Dots Using Mesoporous Silica Spheres as Nanoreactors. Chem. Commun. 2011, 47, 764– 766, DOI: 10.1039/c0cc03092aGoogle Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFGrtLnI&md5=b561241f3859372e551e8f68e462398aSynthesis of photoluminescent carbogenic dots using mesoporous silica spheres as nanoreactorsZong, Jie; Zhu, Yihua; Yang, Xiaoling; Shen, Jianhua; Li, ChunzhongChemical Communications (Cambridge, United Kingdom) (2011), 47 (2), 764-766CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)A novel and facile approach for prepg. hydrophilic carbogenic dots (CDs) has been developed with mesoporous silica spheres as nanoreactors by using an impregnation method. The resulting highly efficient photoluminescent CDs without any further treatment are monodisperse, photostable and of low toxicity, and show excellent luminescence properties.
- 28Wang, L.; Wang, Y.; Xu, T.; Liao, H.; Yao, C.; Liu, Y.; Li, Z.; Chen, Z.; Pan, D.; Sun, L.; Wu, M. Gram-Scale Synthesis of Single-Crystalline Graphene Quantum Dots with Superior Optical Properties. Nat. Commun. 2014, 5, 5357 DOI: 10.1038/ncomms6357Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVaksb7N&md5=fdf58a5d6ad1c880a5034fb4517053eaGram-scale synthesis of single-crystalline graphene quantum dots with superior optical propertiesWang, Liang; Wang, Yanli; Xu, Tao; Liao, Haobo; Yao, Chenjie; Liu, Yuan; Li, Zhen; Chen, Zhiwen; Pan, Dengyu; Sun, Litao; Wu, MinghongNature Communications (2014), 5 (), 5357CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Graphene quantum dots (GQDs) have various alluring properties and potential applications, but their large-scale applications are limited by current synthetic methods that commonly produce GQDs in small amts. Moreover, GQDs usually exhibit polycryst. or highly defective structures and thus poor optical properties. Here we report the gram-scale synthesis of single-cryst. GQDs by a facile mol. fusion route under mild and green hydrothermal conditions. The synthesis involves the nitration of pyrene followed by hydrothermal treatment in alk. aq. solns., where alk. species play a crucial role in tuning their size, functionalization and optical properties. The single-cryst. GQDs are bestowed with excellent optical properties such as bright excitonic fluorescence, strong excitonic absorption bands extending to the visible region, large molar extinction coeffs. and long-term photostability. These high-quality GQDs can find a large array of novel applications in bioimaging, biosensing, light emitting diodes, solar cells, hydrogen prodn., fuel cells and supercapacitors.
- 29Ding, Z.; Li, F.; Wen, J.; Wang, X.; Sun, R. Gram-Scale Synthesis of Single-Crystalline Graphene Quantum Dots Derived from Lignin Biomass. Green Chem. 2018, 20, 1383– 1390, DOI: 10.1039/c7gc03218hGoogle Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVWgt7g%253D&md5=c7b9c345e9a6c5e8edbef23cb6c9f36fGram-scale synthesis of single-crystalline graphene quantum dots derived from lignin biomassDing, Zheyuan; Li, Fengfeng; Wen, Jialong; Wang, Xiluan; Sun, RuncangGreen Chemistry (2018), 20 (6), 1383-1390CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Renewable, cheap, and green biomass resources could meet the urgent need for producing graphene quantum dots (GQDs) on a large scale if high quality can be obtained. We report the gram-scale synthesis of single-cryst. GQDs derived from lignin biomass via a 2-step method. The synthetic processes involve the oxidized cleavage step followed by the arom. refusion step of alkali lignin mols. Notably, this approach successively converts the biomass commonly considered as waste into a high-valued nanoscale product. The as-prepd. single-cryst. GQDs, presenting a hexagonal honeycomb graphene network, are 1-3 at. layers thick. Due to the bright fluorescence, up-conversion properties, long-term photostability, water soly. and biocompatibility, these high quality GQDs have potential to be excellent nanoprobes for multicolor bioimaging. The utilization of renewable biomass resources paves the way for green, low-cost, and large-scale prodn. of high quality GQDs and allows for the development of sustainable applications.
- 30Berglund, L.; Anugwom, I.; Hedenström, M.; Aitomäki, Y.; Mikkola, J. P.; Oksman, K. Switchable Ionic Liquids Enable Efficient Nanofibrillation of Wood Pulp. Cellulose 2017, 24, 3265– 3279, DOI: 10.1007/s10570-017-1354-2Google ScholarThere is no corresponding record for this reference.
- 31Suryawanshi, A.; Biswal, M.; Mhamane, D.; Gokhale, R.; Patil, S.; Guin, D.; Ogale, S. Large Scale Synthesis of Graphene Quantum Dots (GQDs) from Waste Biomass and Their Use as an Efficient and Selective Photoluminescence on-off-on Probe for Ag+ions. Nanoscale 2014, 6, 11664– 11670, DOI: 10.1039/c4nr02494jGoogle Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1Kkt7rJ&md5=ac018f9f51b70d9d2c5ae0ef174d649bLarge scale synthesis of graphene quantum dots (GQDs) from waste biomass and their use as an efficient and selective photoluminescence on-off-on probe for Ag+ ionsSuryawanshi, Anil; Biswal, Mandakini; Mhamane, Dattakumar; Gokhale, Rohan; Patil, Shankar; Guin, Debanjan; Ogale, SatishchandraNanoscale (2014), 6 (20), 11664-11670CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Graphene quantum dots (GQDs) are synthesized from bio-waste and are further modified to produce amine-terminated GQDs (Am-GQDs) which have higher dispersibility and photoluminescence intensity than those of GQDs. A strong fluorescence quenching of Am-GQDs (switch-off) is obsd. for a no. of metal ions, but only for the Ag+ ions is the original fluorescence regenerated (switch-on) upon addn. of L-cysteine.
- 32Ran, C.; Wang, M.; Gao, W.; Yang, Z.; Shao, J.; Deng, J.; Song, X. A General Route to Enhance the Fluorescence of Graphene Quantum Dots by Ag Nanoparticles. RSC Adv. 2014, 4, 21772– 21776, DOI: 10.1039/c4ra03542aGoogle Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXovVeht7c%253D&md5=3490ea78508ce9a21135d73f02518520A general route to enhance the fluorescence of graphene quantum dots by Ag nanoparticlesRan, Chenxin; Wang, Minqiang; Gao, Weiyin; Yang, Zhi; Shao, Jinyou; Deng, Jianping; Song, XiaohuiRSC Advances (2014), 4 (42), 21772-21776CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Graphene quantum dots (GQDs)/Ag nanoparticles with an unexpected quantum yield of 16.3% are synthesized by an efficient simple solvothermal method at atm. pressure. Exptl. results show that the enhanced fluorescence is caused by the plasmonic effect of the Ag nanoparticles. The possible mechanism of this fluorescence enhancement is also proposed.
- 33Gan, Z. X.; Xiong, S. J.; Wu, X. L.; He, C. Y.; Shen, J. C.; Chu, P. K. Mn2+-Bonded Reduced Graphene Oxide with Strong Radiative Recombination in Broad Visible Range Caused by Resonant Energy Transfer. Nano Lett. 2011, 11, 3951– 3956, DOI: 10.1021/nl202240sGoogle Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGnu7fF&md5=0341de856ee10629345ef8fbcf86d798Mn2+-Bonded Reduced Graphene Oxide with Strong Radiative Recombination in Broad Visible Range Caused by Resonant Energy TransferGan, Z.-X.; Xiong, S.-J.; Wu, X.-L.; He, C.-Y.; Shen, J.-C.; Chu, Paul K.Nano Letters (2011), 11 (9), 3951-3956CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The photoluminescence (PL) characteristics of Mn2+-bonded reduced graphene oxide (rGO) are studied in details. The Mn2+-bonded rGO is synthesized using MnO2-decorated GO as the intermediate products and ideal tunable PL is obtained by enhancing the long-wavelength (450-550 nm) emission. The PL spectra excited by different wavelengths are analyzed to elucidate the mechanism, and the resonant energy transfer between Mn2+ and sp2 clusters of the rGO appears to be responsible for the enhanced long-wavelength emission. To examine the effect of Mn2+ on the long-wavelength emission from the Mn2+-bonded rGO, the PL characteristics of Mn2+-bonded rGO with smaller Mn concns. are studied and weaker emission is obsd. Theor. calcn. corroborates the exptl. results.
- 34Bao, L.; Zhang, Z. L.; Tian, Z. Q.; Zhang, L.; Liu, C.; Lin, Y.; Qi, B.; Pang, D. W. Electrochemical Tuning of Luminescent Carbon Nanodots: From Preparation to Luminescence Mechanism. Adv. Mater. 2011, 23, 5801– 5806, DOI: 10.1002/adma.201102866Google Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFOnsb7N&md5=f3f5e7a249d54b38a8f218f4d183c6e0Electrochemical Tuning of Luminescent Carbon Nanodots: From Preparation to Luminescence MechanismBao, Lei; Zhang, Zhi-Ling; Tian, Zhi-Quan; Zhang, Li; Liu, Cui; Lin, Yi; Qi, Baoping; Pang, Dai-WenAdvanced Materials (Weinheim, Germany) (2011), 23 (48), 5801-5806CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The authors propose a new strategy to controllably prep. luminescent carbon nanodots (C-dots) by electrochem. etching of carbon fibers. Monodisperse luminescent C-dots can be obtained controllably by only adjusting the applied potentials, without further sepns. or surface passivation. The authors explore the effects of size and surface oxidn. degree on the luminescence of C-dots in detail and propose a surface oxidn.-related luminescence mechanism for C-dots. Surface states are a key to the luminescence of the C-dots. Red-shifted emissions have been obsd. for the C-dots with a high surface oxidn. degree.
- 35Dong, Y.; Chen, C.; Zheng, X.; Gao, L.; Cui, Z.; Yang, H.; Guo, C.; Chi, Y.; Li, C. M. One-Step and High Yield Simultaneous Preparation of Single- and Multi-Layer Graphene Quantum Dots from CX-72 Carbon Black. J. Mater. Chem. 2012, 22, 8764– 8766, DOI: 10.1039/c2jm30658aGoogle Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XltlGlsLo%253D&md5=fb1e2db0300711ddf67d6c3cc135b36dOne-step and high yield simultaneous preparation of single- and multi-layer graphene quantum dots from CX-72 carbon blackDong, Yongqiang; Chen, Congqiang; Zheng, Xinting; Gao, Lili; Cui, Zhiming; Yang, Hongbin; Guo, Chunxian; Chi, Yuwu; Li, Chang MingJournal of Materials Chemistry (2012), 22 (18), 8764-8766CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A facile, low cost and high yield method was developed to prep. single- and multi-layer graphene quantum dots (GQDs) from XC-72 C black by chem. oxidn. The single-layer GQDs are excellent probes for cellular imaging, while the multi-layer GQDs may offer great potential applications in optoelectronic devices.
- 36Gao, T.; Wang, X.; Yang, L. Y.; He, H.; Ba, X. X.; Zhao, J.; Jiang, F. L.; Liu, Y. Red, Yellow, and Blue Luminescence by Graphene Quantum Dots: Syntheses, Mechanism, and Cellular Imaging. ACS Appl. Mater. Interfaces 2017, 9, 24846– 24856, DOI: 10.1021/acsami.7b05569Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFSnurbK&md5=ce786b3b4e87cae87f1c16e9d1b2145dRed, Yellow, and Blue Luminescence by Graphene Quantum Dots: Syntheses, Mechanism, and Cellular ImagingGao, Tian; Wang, Xi; Yang, Li-Yun; He, Huan; Ba, Xiao-Xu; Zhao, Jie; Jiang, Feng-Lei; Liu, YiACS Applied Materials & Interfaces (2017), 9 (29), 24846-24856CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Owing to their excellent photoluminescence (PL) properties, good biocompatibility, and low toxicity, graphene quantum dots (GQDs) are widely applied in bioimaging, biosensing, and so forth. However, further development of GQDs is limited by their synthetic methodol. and unclear PL mechanism. Therefore, it is urgent to find efficient and universal methods for the synthesis of GQDs with high stability, controllable surface properties, and tunable PL emission wavelength. By coating with polyethyleneimine (PEI) of different mol. wts., blue-, yellow-, and red-emitting GQDs were successfully prepd. By TEM, at. force microscopy, and dynamic light scattering, the characterization of size and morphol. revealed that blue-emitting PEI1800 GQDs were monocoated, like jelly beans, and red-emitting PEI600 GQDs were multicoated, like capsules. The amidation reaction between carboxyl and amide functional groups played an important role in the coating process, as evidenced by IR spectroscopy and theor. calcn. with d. functional theory B3LYP/6-31G*. The PL-tunable GQDs exhibited an excellent chem. stability and extremely low cytotoxicity, and they had been shown to be feasible for bioimaging, making these GQDs highly attractive for a wide variety of applications, including multicolor imaging and bioanal.
- 37Fan, T.; Zeng, W.; Tang, W.; Yuan, C.; Tong, S.; Cai, K.; Liu, Y.; Huang, W.; Min, Y.; Epstein, A. J. Controllable Size-Selective Method to Prepare Graphene Quantum Dots from Graphene Oxide. Nanoscale Res. Lett. 2015, 10, 55 DOI: 10.1186/s11671-015-0783-9Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2MjitFCmuw%253D%253D&md5=6d86dbb2509aaa8eb6953e007d14aaa4Controllable size-selective method to prepare graphene quantum dots from graphene oxideFan Tianju; Zeng Wenjin; Tang Wei; Yuan Chunqiu; Tong Songzhao; Cai Kaiyu; Liu Yidong; Huang Wei; Min Yong; Epstein Arthur JNanoscale research letters (2015), 10 (), 55 ISSN:1931-7573.We demonstrated one-step method to fabricate two different sizes of graphene quantum dots (GQDs) through chemical cutting from graphene oxide (GO), which had many advantages in terms of simple process, low cost, and large scale in manufacturing with higher production yield comparing to the reported methods. Several analytical methods were employed to characterize the composition and morphology of the resultants. Bright blue luminescent GQDs were obtained with a produced yield as high as 34.8%. Moreover, how the different sizes affect fluorescence wavelength mechanism was investigated in details.
- 38Abdul, G.; Zhu, X.; Chen, B. Structural Characteristics of Biochar-Graphene Nanosheet Composites and Their Adsorption Performance for Phthalic Acid Esters. Chem. Eng. J. 2017, 319, 9– 20, DOI: 10.1016/j.cej.2017.02.074Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXktFWitLc%253D&md5=387d653175c7044a07e4a4f09bf24d3aStructural characteristics of biochar-graphene nanosheet composites and their adsorption performance for phthalic acid estersAbdul, Ghaffar; Zhu, Xiaoying; Chen, BaoliangChemical Engineering Journal (Amsterdam, Netherlands) (2017), 319 (), 9-20CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)To create more active sites on biochar surface, biochar-graphene (BG) nanosheet composites were prepd. by 1-step facile dip coating following thermal route at 3 different temps., in addn. to biochars (300, 500, 700°). The morphol. and structural compn. of biochars and BG composites were examd. by SEM, TEM, BET-N and CO2, Raman, FTIR, XPS, TGA and CHN elemental anal. It was found that graphene nanosheets (GNS, ∼1 μm, 0.1% mass) could ensure relatively higher surface area (N and CO2), porous structure and thermal stability within BG composites. BG composites portrayed the existence of GNS bearing cavities and evidently increased the graphitic structure. The adsorption capabilities of biochars and BG composites towards di-Me phthalate (DMP), di-Et phthalate (DEP), and di-Bu phthalate (DBP) as model phthalic acid esters (PAEs) were examd. by batch sorption technique. The BG composites exhibited the increased adsorption capacity comparatively to biochars. The pseudo-2nd-order kinetic rate (k2) illustrated that adsorption of PAEs was efficient and smaller mol. (DMP) was quicker to pore-diffusion mechanism. The arom. sheets of biochars and GNS on biochars dominated the π-π EDA (electron donor-acceptor) interaction for ring structure of DMP mol., whereas adsorption of DBP was attributed to hydrophobicity. The surface morphol. and compn. of biochars can be regulated with GNS to promote the adsorption capacity and kinetics for effective pollutant remediation and could be considered as promising adsorbent for various org. contaminants.
- 39Ghani, W. A. W. A. K.; Mohd, A.; da Silva, G.; Bachmann, R. T.; Taufiq-Yap, Y. H.; Rashid, U.; Al-Muhtaseb, A. H. Biochar Production from Waste Rubber-Wood-Sawdust and Its Potential Use in C Sequestration: Chemical and Physical Characterization. Ind. Crops Prod. 2013, 44, 18– 24, DOI: 10.1016/j.indcrop.2012.10.017Google ScholarThere is no corresponding record for this reference.
- 40Das, O.; Kim, N. K.; Kalamkarov, A. L.; Sarmah, A. K.; Bhattacharyya, D. Biochar to the Rescue: Balancing the Fire Performance and Mechanical Properties of Polypropylene Composites. Polym. Degrad. Stab. 2017, 144, 485– 496, DOI: 10.1016/j.polymdegradstab.2017.09.006Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFCqu7jF&md5=29d313e17449902923f151973c101b10Biochar to the rescue: Balancing the fire performance and mechanical properties of polypropylene compositesDas, Oisik; Kim, Nam Kyeun; Kalamkarov, Alexander L.; Sarmah, Ajit K.; Bhattacharyya, DebesPolymer Degradation and Stability (2017), 144 (), 485-496CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Biochar based wood/polypropylene (PP) composites were manufd. with two flame retardants (FRs): ammonium polyphosphate/APP and magnesium hydroxide/Mg(OH)2. The amts. of wood and biochar were alternated for accommodating the FRs in each blend. Flammability and mech. characterization for both the batches contg. different FRs were done. Having higher proportion of biochar and less wood is beneficial to reduce flammability. The thermally stable biochar contributes to formation of effective char to restrict O2 transfer into PP. The higher wt. ratio of biochar than wood in the composites compromised the tensile and flexural strengths to some extent as the APP and Mg(OH)2 particles were trapped inside biochar pores consequently reducing the effectiveness of biochar pore infiltration by PP. In general, addn. of biochar with a woody biomass (with FRs) to neat PP significantly impedes its flammability while enhancing certain mech. properties, such as flexural strength and tensile/flexural moduli and preserving the tensile strength.
- 41Vázquez-Nakagawa, M.; Rodríguez-Pérez, L.; Herranz, M. A.; Martín, N. Chirality Transfer from Graphene Quantum Dots. Chem. Commun. 2016, 52, 665– 668, DOI: 10.1039/c5cc08890aGoogle Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvVGnt7bE&md5=503b93cd7fa3e857cdfa40b6509e0dedChirality transfer from graphene quantum dotsVazquez-Nakagawa, M.; Rodriguez-Perez, L.; Herranz, M. A.; Martin, N.Chemical Communications (Cambridge, United Kingdom) (2016), 52 (4), 665-668CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Chiral graphene quantum dots were prepd. by acidic exfoliation and oxidn. of graphite, dialysis, and esterification with enantiomerically pure (R) or (S)-2-phenyl-1-propanol. CD studies support the formation of supramol. aggregates with pyrene mols., where a transfer of chirality occurs from the chiral graphene quantum dots to the pyrene.
- 42Dervishi, E.; Ji, Z.; Htoon, H.; Sykora, M.; Doorn, S. K. Raman Spectroscopy of Bottom-up Synthesized Graphene Quantum Dots: Size and Structure Dependence. Nanoscale 2019, 11, 16571– 16581, DOI: 10.1039/c9nr05345jGoogle Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhs1ahs7nO&md5=85a91fe140316a11827a49cc66afe7cfRaman spectroscopy of bottom-up synthesized graphene quantum dots: size and structure dependenceDervishi, Enkeleda; Ji, Zhiqiang; Htoon, Han; Sykora, Milan; Doorn, Stephen K.Nanoscale (2019), 11 (35), 16571-16581CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Graphene quantum dots (GQDs) have attracted significant interest as synthetically tunable optoelectronic and photonic materials that can also serve as model systems for understanding size-dependent behaviors of related graphene structures such as nanoribbons. We present a Raman spectroscopy study of bottom-up synthesized GQDs with lateral dimensions between 0.97 to 1.62 nm, well-defined (armchair) edge type, and fully benzenoid structures. For a better understanding of obsd. size-dependent trends, the study is extended to larger graphene structures including nano-graphene platelets (>25 nm) and large-area graphene. Raman spectra of GQDs reveal the presence of D and G bands, as well as higher order modes (2D, D + G, and 2G). The D and G band frequencies and intensity were found to increase as GQD size increases, while higher order modes (2D, D + G, and 2G) also increased in intensity and became more well-defined. The integrated intensity ratios of D and G bands (ID/IG) increase as the size of the GQDs approaches 2 nm and rapidly decrease for larger graphene structures. We present a quant. comparison of ID/IG ratios for the GQDs and for defects introduced into large area graphenes through ion bombardment, for which inter-defect distances are comparable to the sizes of GQDs studied here. Close agreement suggests the ID/IG ratio as a size diagnostic for other nanographenes. Finally, we show that Raman spectroscopy is also a good diagnostic tool for monitoring the formation of bottom-up synthesized GQDs.
- 43Jia, H.; Cai, Y.; Lin, J.; Liang, H.; Qi, J.; Cao, J.; Feng, J.; Fei, W. D. Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High-Potential Window Electrodes for High-Performance Supercapacitors. Adv. Sci. 2018, 5, 1700887 DOI: 10.1002/advs.201700887Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1MbkslSntg%253D%253D&md5=95d3a762e41e864320db28ce54057244Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High-Potential Window Electrodes for High-Performance SupercapacitorsJia Henan; Cai Yifei; Lin Jinghuang; Liang Haoyan; Qi Junlei; Cao Jian; Feng Jicai; Fei WeiDongAdvanced science (Weinheim, Baden-Wurttemberg, Germany) (2018), 5 (5), 1700887 ISSN:2198-3844.The potential window of aqueous supercapacitors is limited by the theoretical value (≈1.23 V) and is usually lower than ≈1 V, which hinders further improvements for energy density. Here, a simple and scalable method is developed to fabricate unique graphene quantum dot (GQD)/MnO2 heterostructural electrodes to extend the potential window to 0-1.3 V for high-performance aqueous supercapacitor. The GQD/MnO2 heterostructural electrode is fabricated by GQDs in situ formed on the surface of MnO2 nanosheet arrays with good interface bonding by the formation of Mn-O-C bonds. Further, it is interesting to find that the potential window can be extended to 1.3 V by a potential drop in the built-in electric field of the GQD/MnO2 heterostructural region. Additionally, the specific capacitance up to 1170 F g(-1) at a scan rate of 5 mV s(-1) (1094 F g(-1) at 0-1 V) and cycle performance (92.7%@10 000 cycles) between 0 and 1.3 V are observed. A 2.3 V aqueous GQD/MnO2-3//nitrogen-doped graphene ASC is assembled, which exhibits the high energy density of 118 Wh kg(-1) at the power density of 923 W kg(-1). This work opens new opportunities for developing high-voltage aqueous supercapacitors using in situ formed heterostructures to further increase energy density.
- 44Liu, J.; Zhou, Y.; Xie, Z.; Li, Y.; Liu, Y.; Sun, J.; Ma, Y.; Terasaki, O.; Chen, L. Conjugated Copper–Catecholate Framework Electrodes for Efficient Energy Storage. Angew. Chem., Int. Ed. 2020, 59, 1081– 1086, DOI: 10.1002/anie.201912642Google Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVajsr3E&md5=0f7e7b653ecffda622dd412d203e2f4bConjugated Copper-Catecholate Framework Electrodes for Efficient Energy StorageLiu, Jingjuan; Zhou, Yi; Xie, Zhen; Li, Yang; Liu, Yunpeng; Sun, Jie; Ma, Yanhang; Terasaki, Osamu; Chen, LongAngewandte Chemie, International Edition (2020), 59 (3), 1081-1086CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A conjugated copper(II) catecholate based metal-org. framework (namely Cu-DBC) was prepd. using a D2-sym. redox-active ligand in a copper bis(dihydroxy) coordination geometry. The π-d conjugated framework exhibits typical semiconducting behavior with a high elec. cond. of ca. 1.0 S m-1 at room temp. Benefiting from the good elec. cond. and the excellent redox reversibility of both ligand and copper centers, Cu-DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g-1 at a discharge rate of 0.2 A g-1. Moreover, the sym. solid-state supercapacitor of Cu-DBC exhibits high areal (879 mF cm-2) and volumetric (22 F cm-3) capacitances, as well as good rate capability. These metrics are superior to most reported MOF-based supercapacitors, demonstrating promising applications in energy-storage devices.
- 45Luo, J.; Wang, J.; Liu, S.; Wu, W.; Jia, T.; Yang, Z.; Mu, S.; Huang, Y. Graphene Quantum Dots Encapsulated Tremella-like NiCo2O4 for Advanced Asymmetric Supercapacitors. Carbon 2019, 146, 1– 8, DOI: 10.1016/j.carbon.2019.01.078Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisFCrsbc%253D&md5=18e298c7c1e5086fd82833e884410a60Graphene quantum dots encapsulated tremella-like NiCo2O4 for advanced asymmetric supercapacitorsLuo, Jiahuan; Wang, Jing; Liu, Sen; Wu, Weiming; Jia, Taixuan; Yang, Ze; Mu, Shichun; Huang, YunhuiCarbon (2019), 146 (), 1-8CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)A tremella-like NiCo2O4@graphene quantum dots (GQDs) composite is prepd. where the tremella-like NiCo2O4 is homogeneously encapsulated by GQDs. Herein, the GQDs based on π-conjugated core with abundant edge sites, make NiCo2O4 favorable for advanced elec. energy storage (EES). In terms of the synergistic effect between the conductive GQDs and tremella-like NiCo2O4, the as prepd. NiCo2O4@GQDs composite exhibits an excellent specific capacitance of 1242 F g-1 at 30 A g-1 in 2.0 M KOH electrolytes, much higher than that of pristine NiCo2O4 (790 F g-1 at 30 A g-1). Also, it manifests outstanding cycle stability (99% capacitance retention after 4000 cycles). Furthermore, an asym. supercapacitor (ASC) is assembled by pairing NiCo2O4@GQDs composite as pos. electrode and activated carbon (AC) as neg. electrode (NiCo2O4@GQDs//AC), and its specific energy d. is as high as 38 W h kg-1 at a power d. of 800 W kg-1.
- 46El-Kady, M. F.; Strong, V.; Dubin, S.; Kaner, R. B. Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors. Science 2012, 335, 1326– 1330, DOI: 10.1126/science.1216744Google Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xjs1Smurw%253D&md5=301781d36eac2b361aa04ddafb874cecLaser Scribing of High-Performance and Flexible Graphene-Based Electrochemical CapacitorsEl-Kady, Maher F.; Strong, Veronica; Dubin, Sergey; Kaner, Richard B.Science (Washington, DC, United States) (2012), 335 (6074), 1326-1330CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Although electrochem. capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. The authors used a std. LightScribe DVD optical drive to do the direct laser redn. of graphite oxide films to graphene. The produced films are mech. robust, show high elec. cond. (1738 S per m) and sp. surface area (1520 square meters per g), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy d. values in different electrolytes while maintaining the high power d. and excellent cycle stability of ECs. Also, these ECs maintain excellent electrochem. attributes under high mech. stress and thus hold promise for high-power, flexible electronics.
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Abstract
Figure 1
Figure 1. Schematic representation of the preparation steps for GD-doped carbon aerogel. (a) Preparation of carbon aerogel from lignin/CNF suspension. (b) Synthesis of GDs from biochar using oxidative acid treatment involving 3:1 concentration of H2SO4/HNO3; the reaction mixture was refluxed for 6 h at 90 °C. (c) Surface doping of prepared carbon aerogels using GDs synthesized from biochar.
Figure 2
Figure 2. (a) UV–visible spectrum. (b) Photoluminescence (PL) spectra at different excitation wavelengths, showing the optical properties of the produced GDs in an aqueous medium (0.01 wt %). (c) Atomic force microscopic image of GDs. (d) TEM image showing graphene particles with an ordered carbon structure and a size range of 5–15 nm.
Figure 3
Figure 3. (a) FTIR spectrum of GDs exhibiting numerous surface functional groups. (b) Thermogravimetric analysis of GDs compared to the biochar precursor showing a higher weight loss of GDs owing to the decomposition of carboxylic acid groups. (c) Thermogravimetric analysis of KL and CNF. (d) Raman spectra of biochar precursor, GDs prepared from biochar, and carbon aerogel KLCA60. (e) X-ray diffractometry of the GDs and KLCA60.
Figure 4
Figure 4. Microstructure of the prepared materials. (a) and (e) Longitudinal views of KLCA60 and GD-doped KLCA60; magnified images of the longitudinal sections showing the surface texture of both are shown in (b) and (f). Cross-sectional views of KLCA60 and GD-doped KLCA60 are shown in (c) and (g), and the respective high magnification images are shown in (d) and (h).
Figure 5
Figure 5. (a) Solid-state photoluminescence (PL) spectrum of KLCA60 doped with GDs at 315 nm excitation wavelength. (b) Nitrogen adsorption isotherms of KLCA60 and GD-incorporated KLCA60.
Figure 6
Figure 6. (a) and (b) CV curves of supercapacitors composed of KLCA60 and GD-doped KLCA60 at different scan rates. (c) and (d) GCD curves of KLCA60 and GD-doped KLCA60 at different current densities.
Figure 7
Figure 7. Results from the electrochemical analysis. (a) Specific capacitances for KLCA60 at different current densities and (b) specific capacitances of GD-doped KLCA60 at different current densities obtained from GCD analysis. Capacitance contribution calculation using Trasatti method: (c) plot of the reciprocal of the gravimetric capacitance (C–1) against the square root of the scan rate (ν0.5). (d) Plot of C against the reciprocal of the square root of the scan rate (ν–0.5). (e) Nyquist plots obtained from EIS measurements and (f) Ragone plots of the carbon aerogels and GD-incorporated carbon aerogels.
References
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- 6Wang, J.; Ding, B.; Xu, Y.; Shen, L.; Dou, H.; Zhang, X. Crumpled Nitrogen-Doped Graphene for Supercapacitors with High Gravimetric and Volumetric Performances. ACS Appl. Mater. Interfaces 2015, 7, 22284– 22291, DOI: 10.1021/acsami.5b054286https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsFCjur3J&md5=09086ef788c1b4043f7df9dace6fdd12Crumpled Nitrogen-Doped Graphene for Supercapacitors with High Gravimetric and Volumetric PerformancesWang, Jie; Ding, Bing; Xu, Yunling; Shen, Laifa; Dou, Hui; Zhang, XiaogangACS Applied Materials & Interfaces (2015), 7 (40), 22284-22291CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Graphene is considered a promising electrochem. capacitors electrode material due to its high surface area and high elec. cond. However, restacking interactions between graphene nanosheets significantly decrease the ion-accessible surface area and impede electronic and ionic transfer. This would, in turn, severely hinder the realization of high energy d. Herein, we report a strategy for prepn. of few-layer graphene material with abundant crumples and high-level nitrogen doping. The two-dimensional graphene nanosheets (CNG) feature high ion-available surface area, excellent electronic and ion transfer properties, and high packing d., permitting the CNG electrode to exhibit excellent electrochem. performance. In ionic liq. electrolyte, the CNG electrode exhibits gravimetric and volumetric capacitances of 128 F g-1 and 98 F cm-3, resp., achieving gravimetric and volumetric energy densities of 56 Wh kg-1 and 43 Wh L-1. The prepn. strategy described here provides a new approach for developing a graphene-based supercapacitor with high gravimetric and volumetric energy densities.
- 7Ganganboina, A. B.; Dutta Chowdhury, A.; Doong, R. A. New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance Supercapacitors. ACS Sustainable Chem. Eng. 2017, 5, 4930– 4940, DOI: 10.1021/acssuschemeng.7b003297https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXmvVGntbs%253D&md5=d3af236df4c136037866ae80e2190820New Avenue for Appendage of Graphene Quantum Dots on Halloysite Nanotubes as Anode Materials for High Performance SupercapacitorsGanganboina, Akhilesh Babu; Dutta Chowdhury, Ankan; Doong, Ruey-anACS Sustainable Chemistry & Engineering (2017), 5 (6), 4930-4940CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Graphene quantum dots (GQDs) are a newly developed graphene family with good elec. cond. and high theor. capacitance, while halloysite nanotubes (HNTs) are naturally occurring layered mineral materials contg. high active sites for energy storage support. The combination of HNTs and GQDs can offer a new strategy on the fabrication of eco-friendly electrode materials for high performance supercapacitor applications. Herein, an environmentally friendly GQD-HNT nanocomposite is fabricated in the presence of (3-aminopropyl)-triethoxysilane to provide increased charge storage sites as well as to allow for the fast charge transport for supercapacitor application. Morphol. and surface anal. results show that 5-10 nm GQDs are homogeneously distributed on the surface of APTES-coated HNTs via amide linkage. This new and novel layered nanocomposite can provide accessible electroactive sites and low resistance to accelerate the electrons and electrolyte ion transport, resulting in excellent specific capacitance and high energy d. The specific capacitances of 363-216 F/g at current densities of 0.5-20 A/g are obtained. In addn., the GQD-HNTs exhibit excellent energy d. of 30-50 Wh/kg. Results obtained in this study clearly demonstrate the feasibility of using GQD-HNTs as alternative energy storage materials with increased charge storage sites and fast charge transport for high energy d. supercapacitor applications.
- 8Zhu, Y.; Ji, X.; Pan, C.; Sun, Q.; Song, W.; Fang, L.; Chen, Q.; Banks, C. E. A Carbon Quantum Dot Decorated RuO 2 Network: Outstanding Supercapacitances under Ultrafast Charge and Discharge. Energy Environ. Sci. 2013, 6, 3665– 3675, DOI: 10.1039/c3ee41776j8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvVajtbbI&md5=e8bf5427ebe94121043372469bd6234fA carbon quantum dot decorated RuO2 network: outstanding supercapacitances under ultrafast charge and dischargeZhu, Yirong; Ji, Xiaobo; Pan, Chenchi; Sun, Qingqing; Song, Weixin; Fang, Laibing; Chen, Qiyuan; Banks, Craig E.Energy & Environmental Science (2013), 6 (12), 3665-3675CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)Carbon quantum dots (CQDs) due to their unique properties have recently attracted extensive attention from researchers in many fields. In the present work, a new application in the form of a CQD-based hybrid as an excellent electrode material for supercapacitors is reported for the first time. The CQDs are fabricated by a facile chem. oxidn. method following which they are thermally reduced, and further decorated with RuO2 to obtain the composites. The hybrid exhibits a specific capacitance of 460 F g-1 at an ultrahigh c.d. of 50 A g-1 (41.9 wt% Ru loading), and excellent rate capability (88.6, 84.2, and 77.4% of capacity retention rate at 10, 20, and 50 A g-1 compared with 1 A g-1, resp.). Surprisingly, the hybrid shows exceptional cycling stability with 96.9% capacity retention over 5000 cycles at 5 A g-1. Such remarkable electrochem. performances can be primarily ascribed to the significantly enhanced utilization of RuO2 achieved by the efficient dispersion of tiny reduced CQDs and the formation of a CQD-based hybrid network structure that can facilitate the fast charge transport and ionic motion during the charge-discharge process. Addnl., the contact resistance at the interface between active materials and current collectors is concluded to be a key factor in detg. the performance of the hybrid. These results above demonstrate the great potential of CQD-based hybrid materials in the development of high-performance electrode materials for supercapacitors.
- 9Jian, X.; Li, J. G.; Yang, H. M.; Cao, L. L.; Zhang, E. H.; Liang, Z. H. Carbon Quantum Dots Reinforced Polypyrrole Nanowire via Electrostatic Self-Assembly Strategy for High-Performance Supercapacitors. Carbon 2017, 114, 533– 543, DOI: 10.1016/j.carbon.2016.12.0339https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitFKrtbrN&md5=556ec3f563c5a94f73d35e6d2a69a8d6Carbon quantum dots reinforced polypyrrole nanowire via electrostatic self-assembly strategy for high-performance supercapacitorsJian, Xuan; Li, Jia-gang; Yang, Hui-min; Cao, Le-le; Zhang, Er-hui; Liang, Zhen-haiCarbon (2017), 114 (), 533-543CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)Carbon quantum dots (CQDs) reinforced polypyrrole nanowire (PPy-NW) was constructed via electrostatic self-assembly strategy. The as-made CQDs/PPy-NW composite demonstrated superior electrochem. properties benefited from a dotted line structure with large specific area, more active sites and outstanding electronic cond. As the results, the CQDs/PPy-NW composite electrode displayed a specific capacitance of 306 F g-1 at a c.d. of 0.5 A g-1 and retained 66.8% capacitance when the c.d. increased by 80 times (from 0.5 to 40 A g-1). In addn., the as-fabricated sym. supercapacitor was able to offer a large areal capacitance (248.5 mF cm-2 at 0.2 mA cm-2) and good rate capability, the supercapacitor still retained good cycling stability even at a high c.d. of 5 mA cm-2 (85.2% capacitance retention after 5000 cycles). In conclusion, the good electrochem. properties suggest a great potential of the CQDs/PPy-NW in the development of high-performance supercapacitor electrode materials.
- 10Ahmed, S.; Ahmed, A.; Rafat, M. Supercapacitor Performance of Activated Carbon Derived from Rotten Carrot in Aqueous, Organic and Ionic Liquid Based Electrolytes. J. Saudi Chem. Soc. 2018, 22, 993– 1002, DOI: 10.1016/j.jscs.2018.03.00210https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVensbfP&md5=1fb18bd60a879065b4cca961bce29f7dSupercapacitor performance of activated carbon derived from rotten carrot in aqueous, organic and ionic liquid based electrolytesAhmed, Sultan; Ahmed, Ahsan; Rafat, M.Journal of Saudi Chemical Society (2018), 22 (8), 993-1002CODEN: JSCSFO; ISSN:2212-4640. (Elsevier B.V.)In this work, we report the synthesis of porous activated carbon (AC). AC was derived from rotten carrot, at different values of activating temp. under inert atm., employing chem. activation method and ZnCl2 as activation agent. On the basis of results obsd. by surface area and pore size anal., effect of activation temp. on synthesized AC was detd. Other material properties such as morphol., thermal stability, vibrational response, and crystal structure of prepd. AC were studied using std. techniques of material characterization. Further, the electrochem. performance of synthesized AC was studied as an electrode, in aq., org. and ionic liq. based electrolyte. It was found that the synthesized AC based electrode exhibits highest specific capacitance (135.5 F g-1 at 10 mHz) in aq. electrolyte and highest specific energy (29.1 Wh kg-1 at 2.2 A g-1) and specific power (142.5 kW kg-1 at 2.2 A g-1) in ionic liq. based electrolyte. This shows the suitability of synthesized material for use in energy storage applications.
- 11Genc, R.; Alas, M. O.; Harputlu, E.; Repp, S.; Kremer, N.; Castellano, M.; Colak, S. G.; Ocakoglu, K.; Erdem, E. High-Capacitance Hybrid Supercapacitor Based on Multi-Colored Fluorescent Carbon-Dots. Sci. Rep. 2017, 7, 11222 DOI: 10.1038/s41598-017-11347-111https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1cbmvFelsQ%253D%253D&md5=ec24ad22691ff88a47cc1bc68bc700f8High-Capacitance Hybrid Supercapacitor Based on Multi-Colored Fluorescent Carbon-DotsGenc Rukan; Alas Melis Ozge; Genc Rukan; Harputlu Ersan; Colak Suleyman Gokhan; Ocakoglu Kasim; Repp Sergej; Kremer Nora; Castellano Mike; Erdem Emre; Ocakoglu KasimScientific reports (2017), 7 (1), 11222 ISSN:.Multi-colored, water soluble fluorescent carbon nanodots (C-Dots) with quantum yield changing from 4.6 to 18.3% were synthesized in multi-gram using dated cola beverage through a simple thermal synthesis method and implemented as conductive and ion donating supercapacitor component. Various properties of C-Dots, including size, crystal structure, morphology and surface properties along with their Raman and electron paramagnetic resonance spectra were analyzed and compared by means of their fluorescence and electronic properties. α-Manganese Oxide-Polypyrrole (PPy) nanorods decorated with C-Dots were further conducted as anode materials in a supercapacitor. Reduced graphene oxide was used as cathode along with the dicationic bis-imidazolium based ionic liquid in order to enhance the charge transfer and wetting capacity of electrode surfaces. For this purpose, we used octyl-bis(3-methylimidazolium)diiodide (C8H16BImI) synthesized by N-alkylation reaction as liquid ionic membrane electrolyte. Paramagnetic resonance and impedance spectroscopy have been undertaken in order to understand the origin of the performance of hybrid capacitor in more depth. In particular, we obtained high capacitance value (C = 17.3 μF/cm(2)) which is exceptionally related not only the quality of synthesis but also the choice of electrode and electrolyte materials. Moreover, each component used in the construction of the hybrid supercapacitor is also played a key role to achieve high capacitance value.
- 12Kai, D.; Tan, M. J.; Chee, P. L.; Chua, Y. K.; Yap, Y. L.; Loh, X. J. Towards Lignin-Based Functional Materials in a Sustainable World. Green Chem. 2016, 18, 1175– 1200, DOI: 10.1039/C5GC02616D12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xlt1Ggsw%253D%253D&md5=74dffba3d3a1f6e52aae67d1969c514aTowards lignin-based functional materials in a sustainable worldKai, Dan; Tan, Mein Jin; Chee, Pei Lin; Chua, Yun Khim; Yap, Yong Liang; Loh, Xian JunGreen Chemistry (2016), 18 (5), 1175-1200CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)In light of the incessant consumption of raw materials in the world today, the search for sustainable resources is ever pressing. Lignin, the second most naturally abundant biomass, which makes up 15% to 35% of the cell walls of terrestrial plants, has always been treated as waste and used in low-value applications such as heat and electricity generation. However, its abundance in nature could potentially solve the problem of the rapidly depleting resources if it was successfully translated into a renewable resource or valorized to higher value materials. Advanced lignin modification chem. has generated a no. of functional lignin-based polymers, which integrate both the intrinsic features of lignin and addnl. properties of the grafted polymers. These modified lignin and its copolymers display better miscibility with other polymeric matrixes, leading to improved performance for these lignin/polymer composites. This review summarizes the progress in using such biopolymers as reinforcement fillers, antioxidants, UV adsorbents, antimicrobial agents, carbon precursors and biomaterials for tissue engineering and gene therapy. Recent developments in lignin-based smart materials are discussed as well.
- 13Bajwa, D. S.; Pourhashem, G.; Ullah, A. H.; Bajwa, S. G. A Concise Review of Current Lignin Production, Applications, Products and Their Environment Impact. Ind. Crops Prod. 2019, 139, 111526 DOI: 10.1016/j.indcrop.2019.11152613https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsVCgsbjK&md5=6faa7016346504cd9562d4cdacbbfe34A concise review of current lignin production, applications, products and their environment impactBajwa, D. S.; Pourhashem, G.; Ullah, A. H.; Bajwa, S. G.Industrial Crops and Products (2019), 139 (), 111526CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)A review. Lignin is the second most abundant natural material on the earth. Com., it is generated as a waste product from the paper and ethanol prodn. The worldwide prodn. of lignin is approx. 100 million tonnes/yr valued at USD 732.7 million in 2015. It is expected to reach $913.1 million by 2025 with compd. annual growth rate (CAGR) of 2.2%. Two principal categories of lignin are ligno-sulfonate (∼88%) and kraft lignins (∼9%), however a new category organosolv (∼2%) is now gaining popularity due to the prodn. of second generation biofuels (bioethanol prodn.). The organosolv lignin segment is expected to experience the highest growth over the coming years, at an estd. CAGR of over 5% from 2016 to 2025. Chem. lignin is a polyarom. macromol. The complexity and richness of its functional groups makes it attractive for converting into a variety of value added products like high performance carbon fiber, bio-oil, vanillin, and phenolic resin to name a few. Over the years lignin has been predominantly burnt as fuel for heat and power. Less than 2% of the available lignin was sold, primarily in the formulation of dispersants, adhesives and surfactants. However, in the last decade lignin-based research and new product development has picked significant momentum due to the bio-refinery concept as aging pulp and paper mills need to diversify their products portfolio to maintain their vitality. The emerging biofuel/bioenergy technologies are working to develop value-added co-products from lignin and bio-oil as a means of making the processes more cost effective. There is a resurgence in the demand for lignin for use in binders, adhesives, bioplastics, concrete admixts. and biomedical applications. Effective "upstream" and "downstream" valorization techniques are facilitating fine tuning of lignin as a building block for high value chems. Other market dynamics driving lignin use are stringent regulations for dust control, demand for high quality concrete admixts. and dispersants, and carbon rich products (activated carbon, carbon filer, resins, etc.). To further accelerate development of lignin based products consumer awareness and gap between research and development and consumer products need to be reduced.
- 14Geng, S.; Wei, J.; Jonasson, S.; Hedlund, J.; Oksman, K. Multifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy Storage. ACS Appl. Mater. Interfaces 2020, 12, 7432– 7441, DOI: 10.1021/acsami.9b1995514https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtlWhurk%253D&md5=a1615e53c2f26c21293e7c17482f2beeMultifunctional Carbon Aerogels with Hierarchical Anisotropic Structure Derived from Lignin and Cellulose Nanofibers for CO2 Capture and Energy StorageGeng, Shiyu; Wei, Jiayuan; Jonasson, Simon; Hedlund, Jonas; Oksman, KristiinaACS Applied Materials & Interfaces (2020), 12 (6), 7432-7441CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)In current times, CO2 capture and lightwt. energy storage are receiving significant attention and will be vital functions in next-generation materials. Porous carbonaceous materials have great potential in these areas, whereas most of the developed carbon materials still have significant limitations, such as nonrenewable resources, complex and costly processing, or the absence of tailorable structure. In this study, a new strategy is developed for using the currently underutilized lignin and cellulose nanofibers, which can be extd. from renewable resources to produce high-performance multifunctional carbon aerogels with a tailorable, anisotropic pore structure. Both the macro- and microstructure of the carbon aerogels can be simultaneously controlled by carefully tuning the wt. ratio of lignin to cellulose nanofibers in the precursors, which considerably influences their final porosity and surface area. The designed carbon aerogels demonstrate excellent performance in both CO2 capture and capacitive energy storage, and the best results exhibit a CO2 adsorption capacity of 5.23 mmol g-1 at 273 K and 100 kPa and a specific elec. double-layer capacitance of 124 F g-1 at a c.d. of 0.2 A g-1, indicating that they have great future potential in the relevant applications.
- 15Thomas, B.; Geng, S.; Sain, M.; Oksman, K. Hetero-Porous, High-Surface Area Green Carbon Aerogels for the next-Generation Energy Storage Applications. Nanomaterials 2021, 11, 653 DOI: 10.3390/nano1103065315https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhtVOjtLnF&md5=cba2dbd45cfd99658af4cae5f55a866aHetero-porous, high-surface area green carbon aerogels for the next-generation energy storage applicationsThomas, Bony; Geng, Shiyu; Sain, Mohini; Oksman, KristiinaNanomaterials (2021), 11 (3), 653CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)Various carbon materials have been developed for energy storage applications to address the increasing energy demand in the world. However, the environmentally friendly, renewable, and nontoxic bio-based carbon resources have not been extensively investigated towards high performance energy storage materials. Here, the authors report an anisotropic, hetero-porous, high-surface area carbon aerogel prepd. from renewable resources achieving an excellent elec. double-layer capacitance. Two different green, abundant, and carbon-rich lignins which can be extd. from various biomasses, have been selected as raw materials, i.e., kraft and soda lignins, resulting in clearly distinct phys., structural as well as electrochem. characteristics of the carbon aerogels after carbonization. The obtained green carbon aerogel based on kraft lignin not only demonstrates a competitive specific capacitance as high as 163 F g-1 and energy d. of 5.67 Wh kg-1 at a power d. of 50 W kg-1 when assembled as a two-electrode sym. supercapacitor, but also shows outstanding compressive mech. properties. This reveals the great potential of the carbon aerogels developed in this study for the next-generation energy storage applications requiring green and renewable resources, lightwt., robust storage ability, and reliable mech. integrity.
- 16Liu, C.; Yu, Z.; Neff, D.; Zhamu, A.; Jang, B. Z. Graphene-Based Supercapacitor with an Ultrahigh Energy Density. Nano Lett. 2010, 10, 4863– 4868, DOI: 10.1021/nl102661q16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtl2jtbjF&md5=8986081b4c509727a1aec3ccf003f76bGraphene-Based Supercapacitor with an Ultrahigh Energy DensityLiu, Chenguang; Yu, Zhenning; Neff, David; Zhamu, Aruna; Jang, Bor Z.Nano Letters (2010), 10 (12), 4863-4868CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)A supercapacitor with graphene-based electrodes was found to exhibit a specific energy d. of 85.6 Wh/kg at room temp. and 136 Wh/kg at 80° (all based on the total electrode wt.), measured at a c.d. of 1 A/g. These energy d. values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full use of the highest intrinsic surface capacitance and sp. surface area of single-layer graphene by prepg. curved graphene sheets that will not restack face-to-face. The curved morphol. enables the formation of mesopores accessible to and wettable by environmentally benign ionic liqs. capable of operating at a voltage >4 V.
- 17Li, Z.; Qin, P.; Wang, L.; Yang, C.; Li, Y.; Chen, Z.; Pan, D.; Wu, M. Amine-Enriched Graphene Quantum Dots for High-Pseudocapacitance Supercapacitors. Electrochim. Acta 2016, 208, 260– 266, DOI: 10.1016/j.electacta.2016.05.03017https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xot1Knt74%253D&md5=c85ba596a4fc0ecfe052d14b1ff7186fAmine-enriched Graphene Quantum Dots for High-pseudocapacitance SupercapacitorsLi, Zhen; Qin, Ping; Wang, Liang; Yang, Chengshuai; Li, Yanfeng; Chen, Zhiwen; Pan, Dengyu; Wu, MinghongElectrochimica Acta (2016), 208 (), 260-266CODEN: ELCAAV; ISSN:0013-4686. (Elsevier Ltd.)The applications of C-based supercapacitors were limited by their low energy storage d. owing to their limited active storage sites. To overcome this limitation, amine-enriched porous C electrodes were fabricated by the electrostatic fusion of amine-functionalized single-cryst. graphene quantum dots (GQDs) within conductive, vertically ordered TiO2 nanotube arrays as the collectors. The C films deliver ultrahigh specific capacitance (400-595 F g-1) even beyond the theor. upper limit of single-layer graphene by inducing a high concn. of active amine moieties at edge. Sym. GQD supercapacitors in H2SO4 electrolyte offer energy d. up to 21.8 Wh kg-1 and retain 90% of the initial capacitance after 10000 cyclic voltammetry tests. Amine-enriched GQDs can function as a new kind of highly active, soln.-processable, and low-cost pseudocapacitive materials applicable to high-performance supercapacitors.
- 18Yoo, J. J.; Balakrishnan, K.; Huang, J.; Meunier, V.; Sumpter, B. G.; Srivastava, A.; Conway, M.; Mohana Reddy, A. L.; Yu, J.; Vajtai, R.; Ajayan, P. M. Ultrathin Planar Graphene Supercapacitors. Nano Lett. 2011, 11, 1423– 1427, DOI: 10.1021/nl200225j18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXivFCnurg%253D&md5=f23802077f1d84f7440d041112213f47Ultrathin planar graphene supercapacitorsYoo, Jung Joon; Balakrishnan, Kaushik; Huang, Jingsong; Meunier, Vincent; Sumpter, Bobby G.; Srivastava, Anchal; Conway, Michelle; Reddy, Arava Leela Mohana; Yu, Jin; Vajtai, Robert; Ajayan, Pulickel M.Nano Letters (2011), 11 (4), 1423-1427CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)With the advent of atomically thin and flat layers of conducting materials such as graphene, new designs for thin film energy storage devices with good performance have become possible. Here, we report an "in-plane" fabrication approach for ultrathin supercapacitors based on electrodes comprised of pristine graphene and multilayer reduced graphene oxide. The in-plane design is straightforward to implement and exploits efficiently the surface of each graphene layer for energy storage. The open architecture and the effect of graphene edges enable even the thinnest of devices, made from as grown 1-2 graphene layers, to reach specific capacities up to 80 μFcm-2, while much higher (394 μFcm-2) specific capacities are obsd. multilayer reduced graphene oxide electrodes. The performances of devices with pristine as well as thicker graphene-based structures are examd. using a combination of expts. and model calcns. The demonstrated all solid-state supercapacitors provide a prototype for a broad range of thin-film based energy storage devices.
- 19Abbas, A.; Mariana, L. T.; Phan, A. N. Biomass-Waste Derived Graphene Quantum Dots and Their Applications. Carbon 2018, 140, 77– 99, DOI: 10.1016/j.carbon.2018.08.01619https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhsF2mu7nJ&md5=325a7fe9c7e771b1663091fb8bff06f4Biomass-waste derived graphene quantum dots and their applicationsAbbas, Aumber; Mariana, Lim Tuti; Phan, Anh N.Carbon (2018), 140 (), 77-99CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)A review. Energy crisis, environmental deterioration, and increasing customer needs have compelled scientists to search facile, low cast, and green routes for the prodn. of novel advanced materials from renewable resources. Among various materials explored, carbon-based nanomaterials, esp. graphene and graphene quantum dots (GQDs), have attracted extensive attention recently owning to their intriguing properties, such as high cond., extensive surface area, good biocompatibility, low toxicity, and long life. This review focuses on the conversion of biomass-waste into GQDs through a no. of facile, low cost, and scalable routes. Factors affecting the phys. and chem. properties of GQDs for numerous promising applications have also been discussed. GQDs have shown promising applications in the field of catalysis, carbon fixation, fuel cells, bio-imaging, drug delivery, and gas sensors. Interestingly, the recent and novel applications of GQDs in the conversion and storage of energy has been discussed here. Finally, the remaining challenges, future perspectives and possible research directions in the field are presented.
- 20Yan, Y.; Gong, J.; Chen, J.; Zeng, Z.; Huang, W.; Pu, K.; Liu, J.; Chen, P. Recent Advances on Graphene Quantum Dots: From Chemistry and Physics to Applications. Adv. Mater. 2019, 31, 1808283 DOI: 10.1002/adma.201808283There is no corresponding record for this reference.
- 21Li, Y.; Wu, F.; Jin, X.; Xu, H.; Liu, X.; Shi, G. Preparation and Electrochemical Properties of Graphene Quantum Dots/Biomass Activated Carbon Electrodes. Inorg. Chem. Commun. 2020, 112, 107718 DOI: 10.1016/j.inoche.2019.10771821https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVSmsr3I&md5=30f6034cf7f97c30f9bbaf6468bf54c5Preparation and electrochemical properties of graphene quantum dots/biomass activated carbon electrodesLi, Ying; Wu, Feifei; Jin, Xuan; Xu, Humin; Liu, Xuefeng; Shi, GangInorganic Chemistry Communications (2020), 112 (), 107718CODEN: ICCOFP; ISSN:1387-7003. (Elsevier B.V.)Graphene quantum dots and biomass activated carbon have enormous potential for electrochem. application, which composites as anode materials for lithium ion battery are rarely reported. Here, the rice husk based activated carbon was modified by graphene quantum dots, exhibiting excellent electrochem. performance as an electrode for lithium ion battery. With the introduction of graphene quantum dots, the charge transfer resistance of the electrode was reduced from 577.7 Ω to 123.9 Ω, and the lithium ion diffusion coeff. was increased by 175 times. Meanwhile, the introduction of graphene quantum dots plays an important role in improving the cycle stability of the battery.
- 22Li, L.; Wu, G.; Yang, G.; Peng, J.; Zhao, J.; Zhu, J. J. Focusing on Luminescent Graphene Quantum Dots: Current Status and Future Perspectives. Nanoscale 2013, 5, 4015– 4039, DOI: 10.1039/c3nr33849e22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmvFOqsrg%253D&md5=ec24e752dc6e18aacf2d73aaca268db5Focusing on luminescent graphene quantum dots: current status and future perspectivesLi, Lingling; Wu, Gehui; Yang, Guohai; Peng, Juan; Zhao, Jianwei; Zhu, Jun-JieNanoscale (2013), 5 (10), 4015-4039CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)A review. To obtain graphene-based fluorescent materials, one of the effective approaches is to convert one-dimensional (1D) graphene to 0D graphene quantum dots (GQDs), yielding an emerging nanolight with extraordinary properties due to their remarkable quantum confinement and edge effects. In this review, the state-of-the-art knowledge of GQDs is presented. The synthetic methods were summarized, with emphasis on the top-down routes which possess the advantages of abundant raw materials, large scale prodn. and simple operation. Optical properties of GQDs are also systematically discussed ranging from the mechanism, the influencing factors to the optical tunability. The current applications are also reviewed, followed by an outlook on their future and potential development, involving the effective synthetic methods, systematic photoluminescent mechanism, bandgap engineering, in addn. to the potential applications in bioimaging, sensors, etc.
- 23Gong, X.; Hu, Q.; Chin Paau, M.; Zhang, Y.; Zhang, L.; Shuang, S.; Dong, C.; Choi, M. M. F. High-Performance Liquid Chromatographic and Mass Spectrometric Analysis of Fluorescent Carbon Nanodots. Talanta 2014, 129, 529– 538, DOI: 10.1016/j.talanta.2014.04.00823https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlOmu73N&md5=a49e875d2d423b998cff665754b5b9ffHigh-performance liquid chromatographic and mass spectrometric analysis of fluorescent carbon nanodotsGong, Xiaojuan; Hu, Qin; Man, Chin Paau; Zhang, Yan; Zhang, Lei; Shuang, Shaomin; Dong, Chuan; Choi, Martin M. F.Talanta (2014), 129 (), 529-538CODEN: TLNTA2; ISSN:0039-9140. (Elsevier B.V.)Amino/hydroxyl-functionalized fluorescent carbon nanodots (C-NanoD) are conveniently synthesized based on hydrothermal carbonization of chitosan at 180° C. Dialysis membranes with small cut-off masses (500-1000 Da) were found useful for removing the side-products and low mol. mass species to purify the C-NanoD product. Herein, reversed-phase high-performance liq. chromatog. (RP-HPLC) has been successfully applied to fractionate the C-NanoD product. The elution order of the C-NanoD species present in the sample follows approx. their core sizes from small to large. The sepd. C-NanoD fractions are collected and characterized by UV absorption spectroscopy, photoluminescence (PL) spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and transmission electron microscopy (TEM). All the C-NanoD fractions display a distinctive absorption band at 300 nm, attributing to the n→π* transition of C=O bond. The PL spectra of the fractions display emission peaks at 400-415 nm which are slightly red-shifted with their increase in relative mol. masses. The C-NanoD fractions are fully anatomized by MALDI-TOF MS, displaying their fragmentation mass ion features. The core sizes of some selected C-NanoD are detd. as 1.6, 1.8, 2.5, and 3.1 nm by TEM which are in consistent with their HPLC elution order. The findings highlight the virtues of RP-HPLC to fractionate and reveal the unique characteristics of individual C-NanoD species present in an as-synthesized C-NanoD product which may have potential applications in the fields of bioanal., bioimaging, catalysis, chemosensing, energy storage, and optoelectronics device.
- 24Fringes, S.; Volk, C.; Terrés, B.; Dauber, J.; Engels, S.; Trellenkamp, S.; Stampfer, C. Tunable Capacitive Inter-Dot Coupling in a Bilayer Graphene Double Quantum Dot. Phys. Status Solidi C 2012, 9, 169– 174, DOI: 10.1002/pssc.20110034024https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtFWrt7c%253D&md5=69960af3185f4ccd676e27afa05ac5e4Tunable capacitive inter-dot coupling in a bilayer graphene double quantum dotFringes, Stefan; Volk, Christian; Terres, Bernat; Dauber, Jan; Engels, Stephan; Trellenkamp, Stefan; Stampfer, ChristophPhysica Status Solidi C: Current Topics in Solid State Physics (2012), 9 (2), 169-174CODEN: PSSCGL; ISSN:1610-1642. (Wiley-Blackwell)We report on a double quantum dot which is formed in a width-modulated etched bilayer graphene nanoribbon. A no. of lateral graphene gates enable us to tune the quantum dot energy levels and the tunneling barriers of the device over a wide energy range. Charge stability diagrams and in particular individual triple point pairs allow to study the tunable capacitive inter-dot coupling energy as well as the spectrum of the electronic excited states on a no. of individual triple points. We ext. a mutual capacitive inter-dot coupling in the range of 2-6 meV and an inter-dot tunnel coupling on the order of 1.5 μeV. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).
- 25Feng, J.; Dong, H.; Yu, L.; Dong, L. The Optical and Electronic Properties of Graphene Quantum Dots with Oxygen-Containing Groups: A Density Functional Theory Study. J. Mater. Chem. C 2017, 5, 5984– 5993, DOI: 10.1039/C7TC00631D25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXot1ejurs%253D&md5=3f10a0062c0fac485bc66c791fa0ea1dThe optical and electronic properties of graphene quantum dots with oxygen-containing groups: a density functional theory studyFeng, Jianguang; Dong, Hongzhou; Yu, Liyan; Dong, LifengJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2017), 5 (24), 5984-5993CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)The effects of 5 types of O-contg. functional groups (-COOH, -COC-, -OH, -CHO, and -OMe) on graphene quantum dots (GQDs) are studied using time-dependent d. functional theory (TD-DFT). Their absorption spectra and HOMO-LUMO gaps are quant. analyzed to reveal the influence of different O-contg. groups including their locations and quantities on the optical properties of GQDs. Compared with those on the edge of the GQD plane, O-contg. groups located on the surface have more evident effects on the optical properties. The calcd. HOMO-LUMO gaps of pristine GQDs and edge-functionalized GQDs with -OH, -COOH, -OMe, -CHO, and -COC- are 2.34, 2.32, 2.31, 2.30, 2.27, and 2.15 eV, resp., whereas the HOMO-LUMO gaps of surface-functionalized GQDs with the groups above are 0.36, 0.32, 0.37, 0.39, and 1.86 eV, resp. The influence of surface and edge functionalization on the HOMO-LUMO gap of GQDs is almost opposite. The absorption process is studied along with excited state anal., which includes the oscillator strengths, natural transition orbitals, and charge difference d. Functionalization on the basal plane greatly changes the distribution of electron d. in surface-functionalized GQDs.
- 26Zhu, C.; Yang, S.; Wang, G.; Mo, R.; He, P.; Sun, J.; Di, Z.; Kang, Z.; Yuan, N.; Ding, J.; Ding, G.; Xie, X. A New Mild, Clean and Highly Efficient Method for the Preparation of Graphene Quantum Dots without by-Products. J. Mater. Chem. B 2015, 3, 6871– 6876, DOI: 10.1039/c5tb01093d26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXht1GrsrfI&md5=6b642307a873ec63302e9bbb0f943d77A new mild, clean and highly efficient method for the preparation of graphene quantum dots without by-productsZhu, Chong; Yang, Siwei; Wang, Gang; Mo, Runwei; He, Peng; Sun, Jing; Di, Zengfeng; Kang, Zhenhui; Yuan, Ningyi; Ding, Jianning; Ding, Guqiao; Xie, XiaomingJournal of Materials Chemistry B: Materials for Biology and Medicine (2015), 3 (34), 6871-6876CODEN: JMCBDV; ISSN:2050-7518. (Royal Society of Chemistry)We demonstrated that graphene oxide (GO) can be oxidized and cut into graphene quantum dots (GQDs) by hydroxyl radicals (•OH), which is obtained by the catalytic decompn. of hydrogen peroxide (H2O2) with a tungsten oxide nanowire (W18O49) catalyst. The clean oxidizing agent (H2O2) and the solid catalyst lead to a simple GQD prepg. method without any byproducts. The obtained GQD aq. soln. can be directly applied to fluorescence imaging in vitro without any further purifn. The effect of the W18O49 catalyst on the •OH formation is discussed, and the size of GQDs can be controlled via changing the concn. of hydroxyl radicals.
- 27Zong, J.; Zhu, Y.; Yang, X.; Shen, J.; Li, C. Synthesis of Photoluminescent Carbogenic Dots Using Mesoporous Silica Spheres as Nanoreactors. Chem. Commun. 2011, 47, 764– 766, DOI: 10.1039/c0cc03092a27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFGrtLnI&md5=b561241f3859372e551e8f68e462398aSynthesis of photoluminescent carbogenic dots using mesoporous silica spheres as nanoreactorsZong, Jie; Zhu, Yihua; Yang, Xiaoling; Shen, Jianhua; Li, ChunzhongChemical Communications (Cambridge, United Kingdom) (2011), 47 (2), 764-766CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)A novel and facile approach for prepg. hydrophilic carbogenic dots (CDs) has been developed with mesoporous silica spheres as nanoreactors by using an impregnation method. The resulting highly efficient photoluminescent CDs without any further treatment are monodisperse, photostable and of low toxicity, and show excellent luminescence properties.
- 28Wang, L.; Wang, Y.; Xu, T.; Liao, H.; Yao, C.; Liu, Y.; Li, Z.; Chen, Z.; Pan, D.; Sun, L.; Wu, M. Gram-Scale Synthesis of Single-Crystalline Graphene Quantum Dots with Superior Optical Properties. Nat. Commun. 2014, 5, 5357 DOI: 10.1038/ncomms635728https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXitVaksb7N&md5=fdf58a5d6ad1c880a5034fb4517053eaGram-scale synthesis of single-crystalline graphene quantum dots with superior optical propertiesWang, Liang; Wang, Yanli; Xu, Tao; Liao, Haobo; Yao, Chenjie; Liu, Yuan; Li, Zhen; Chen, Zhiwen; Pan, Dengyu; Sun, Litao; Wu, MinghongNature Communications (2014), 5 (), 5357CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Graphene quantum dots (GQDs) have various alluring properties and potential applications, but their large-scale applications are limited by current synthetic methods that commonly produce GQDs in small amts. Moreover, GQDs usually exhibit polycryst. or highly defective structures and thus poor optical properties. Here we report the gram-scale synthesis of single-cryst. GQDs by a facile mol. fusion route under mild and green hydrothermal conditions. The synthesis involves the nitration of pyrene followed by hydrothermal treatment in alk. aq. solns., where alk. species play a crucial role in tuning their size, functionalization and optical properties. The single-cryst. GQDs are bestowed with excellent optical properties such as bright excitonic fluorescence, strong excitonic absorption bands extending to the visible region, large molar extinction coeffs. and long-term photostability. These high-quality GQDs can find a large array of novel applications in bioimaging, biosensing, light emitting diodes, solar cells, hydrogen prodn., fuel cells and supercapacitors.
- 29Ding, Z.; Li, F.; Wen, J.; Wang, X.; Sun, R. Gram-Scale Synthesis of Single-Crystalline Graphene Quantum Dots Derived from Lignin Biomass. Green Chem. 2018, 20, 1383– 1390, DOI: 10.1039/c7gc03218h29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXisVWgt7g%253D&md5=c7b9c345e9a6c5e8edbef23cb6c9f36fGram-scale synthesis of single-crystalline graphene quantum dots derived from lignin biomassDing, Zheyuan; Li, Fengfeng; Wen, Jialong; Wang, Xiluan; Sun, RuncangGreen Chemistry (2018), 20 (6), 1383-1390CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Renewable, cheap, and green biomass resources could meet the urgent need for producing graphene quantum dots (GQDs) on a large scale if high quality can be obtained. We report the gram-scale synthesis of single-cryst. GQDs derived from lignin biomass via a 2-step method. The synthetic processes involve the oxidized cleavage step followed by the arom. refusion step of alkali lignin mols. Notably, this approach successively converts the biomass commonly considered as waste into a high-valued nanoscale product. The as-prepd. single-cryst. GQDs, presenting a hexagonal honeycomb graphene network, are 1-3 at. layers thick. Due to the bright fluorescence, up-conversion properties, long-term photostability, water soly. and biocompatibility, these high quality GQDs have potential to be excellent nanoprobes for multicolor bioimaging. The utilization of renewable biomass resources paves the way for green, low-cost, and large-scale prodn. of high quality GQDs and allows for the development of sustainable applications.
- 30Berglund, L.; Anugwom, I.; Hedenström, M.; Aitomäki, Y.; Mikkola, J. P.; Oksman, K. Switchable Ionic Liquids Enable Efficient Nanofibrillation of Wood Pulp. Cellulose 2017, 24, 3265– 3279, DOI: 10.1007/s10570-017-1354-2There is no corresponding record for this reference.
- 31Suryawanshi, A.; Biswal, M.; Mhamane, D.; Gokhale, R.; Patil, S.; Guin, D.; Ogale, S. Large Scale Synthesis of Graphene Quantum Dots (GQDs) from Waste Biomass and Their Use as an Efficient and Selective Photoluminescence on-off-on Probe for Ag+ions. Nanoscale 2014, 6, 11664– 11670, DOI: 10.1039/c4nr02494j31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXht1Kkt7rJ&md5=ac018f9f51b70d9d2c5ae0ef174d649bLarge scale synthesis of graphene quantum dots (GQDs) from waste biomass and their use as an efficient and selective photoluminescence on-off-on probe for Ag+ ionsSuryawanshi, Anil; Biswal, Mandakini; Mhamane, Dattakumar; Gokhale, Rohan; Patil, Shankar; Guin, Debanjan; Ogale, SatishchandraNanoscale (2014), 6 (20), 11664-11670CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Graphene quantum dots (GQDs) are synthesized from bio-waste and are further modified to produce amine-terminated GQDs (Am-GQDs) which have higher dispersibility and photoluminescence intensity than those of GQDs. A strong fluorescence quenching of Am-GQDs (switch-off) is obsd. for a no. of metal ions, but only for the Ag+ ions is the original fluorescence regenerated (switch-on) upon addn. of L-cysteine.
- 32Ran, C.; Wang, M.; Gao, W.; Yang, Z.; Shao, J.; Deng, J.; Song, X. A General Route to Enhance the Fluorescence of Graphene Quantum Dots by Ag Nanoparticles. RSC Adv. 2014, 4, 21772– 21776, DOI: 10.1039/c4ra03542a32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXovVeht7c%253D&md5=3490ea78508ce9a21135d73f02518520A general route to enhance the fluorescence of graphene quantum dots by Ag nanoparticlesRan, Chenxin; Wang, Minqiang; Gao, Weiyin; Yang, Zhi; Shao, Jinyou; Deng, Jianping; Song, XiaohuiRSC Advances (2014), 4 (42), 21772-21776CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Graphene quantum dots (GQDs)/Ag nanoparticles with an unexpected quantum yield of 16.3% are synthesized by an efficient simple solvothermal method at atm. pressure. Exptl. results show that the enhanced fluorescence is caused by the plasmonic effect of the Ag nanoparticles. The possible mechanism of this fluorescence enhancement is also proposed.
- 33Gan, Z. X.; Xiong, S. J.; Wu, X. L.; He, C. Y.; Shen, J. C.; Chu, P. K. Mn2+-Bonded Reduced Graphene Oxide with Strong Radiative Recombination in Broad Visible Range Caused by Resonant Energy Transfer. Nano Lett. 2011, 11, 3951– 3956, DOI: 10.1021/nl202240s33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGnu7fF&md5=0341de856ee10629345ef8fbcf86d798Mn2+-Bonded Reduced Graphene Oxide with Strong Radiative Recombination in Broad Visible Range Caused by Resonant Energy TransferGan, Z.-X.; Xiong, S.-J.; Wu, X.-L.; He, C.-Y.; Shen, J.-C.; Chu, Paul K.Nano Letters (2011), 11 (9), 3951-3956CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)The photoluminescence (PL) characteristics of Mn2+-bonded reduced graphene oxide (rGO) are studied in details. The Mn2+-bonded rGO is synthesized using MnO2-decorated GO as the intermediate products and ideal tunable PL is obtained by enhancing the long-wavelength (450-550 nm) emission. The PL spectra excited by different wavelengths are analyzed to elucidate the mechanism, and the resonant energy transfer between Mn2+ and sp2 clusters of the rGO appears to be responsible for the enhanced long-wavelength emission. To examine the effect of Mn2+ on the long-wavelength emission from the Mn2+-bonded rGO, the PL characteristics of Mn2+-bonded rGO with smaller Mn concns. are studied and weaker emission is obsd. Theor. calcn. corroborates the exptl. results.
- 34Bao, L.; Zhang, Z. L.; Tian, Z. Q.; Zhang, L.; Liu, C.; Lin, Y.; Qi, B.; Pang, D. W. Electrochemical Tuning of Luminescent Carbon Nanodots: From Preparation to Luminescence Mechanism. Adv. Mater. 2011, 23, 5801– 5806, DOI: 10.1002/adma.20110286634https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFOnsb7N&md5=f3f5e7a249d54b38a8f218f4d183c6e0Electrochemical Tuning of Luminescent Carbon Nanodots: From Preparation to Luminescence MechanismBao, Lei; Zhang, Zhi-Ling; Tian, Zhi-Quan; Zhang, Li; Liu, Cui; Lin, Yi; Qi, Baoping; Pang, Dai-WenAdvanced Materials (Weinheim, Germany) (2011), 23 (48), 5801-5806CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The authors propose a new strategy to controllably prep. luminescent carbon nanodots (C-dots) by electrochem. etching of carbon fibers. Monodisperse luminescent C-dots can be obtained controllably by only adjusting the applied potentials, without further sepns. or surface passivation. The authors explore the effects of size and surface oxidn. degree on the luminescence of C-dots in detail and propose a surface oxidn.-related luminescence mechanism for C-dots. Surface states are a key to the luminescence of the C-dots. Red-shifted emissions have been obsd. for the C-dots with a high surface oxidn. degree.
- 35Dong, Y.; Chen, C.; Zheng, X.; Gao, L.; Cui, Z.; Yang, H.; Guo, C.; Chi, Y.; Li, C. M. One-Step and High Yield Simultaneous Preparation of Single- and Multi-Layer Graphene Quantum Dots from CX-72 Carbon Black. J. Mater. Chem. 2012, 22, 8764– 8766, DOI: 10.1039/c2jm30658a35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XltlGlsLo%253D&md5=fb1e2db0300711ddf67d6c3cc135b36dOne-step and high yield simultaneous preparation of single- and multi-layer graphene quantum dots from CX-72 carbon blackDong, Yongqiang; Chen, Congqiang; Zheng, Xinting; Gao, Lili; Cui, Zhiming; Yang, Hongbin; Guo, Chunxian; Chi, Yuwu; Li, Chang MingJournal of Materials Chemistry (2012), 22 (18), 8764-8766CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)A facile, low cost and high yield method was developed to prep. single- and multi-layer graphene quantum dots (GQDs) from XC-72 C black by chem. oxidn. The single-layer GQDs are excellent probes for cellular imaging, while the multi-layer GQDs may offer great potential applications in optoelectronic devices.
- 36Gao, T.; Wang, X.; Yang, L. Y.; He, H.; Ba, X. X.; Zhao, J.; Jiang, F. L.; Liu, Y. Red, Yellow, and Blue Luminescence by Graphene Quantum Dots: Syntheses, Mechanism, and Cellular Imaging. ACS Appl. Mater. Interfaces 2017, 9, 24846– 24856, DOI: 10.1021/acsami.7b0556936https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFSnurbK&md5=ce786b3b4e87cae87f1c16e9d1b2145dRed, Yellow, and Blue Luminescence by Graphene Quantum Dots: Syntheses, Mechanism, and Cellular ImagingGao, Tian; Wang, Xi; Yang, Li-Yun; He, Huan; Ba, Xiao-Xu; Zhao, Jie; Jiang, Feng-Lei; Liu, YiACS Applied Materials & Interfaces (2017), 9 (29), 24846-24856CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Owing to their excellent photoluminescence (PL) properties, good biocompatibility, and low toxicity, graphene quantum dots (GQDs) are widely applied in bioimaging, biosensing, and so forth. However, further development of GQDs is limited by their synthetic methodol. and unclear PL mechanism. Therefore, it is urgent to find efficient and universal methods for the synthesis of GQDs with high stability, controllable surface properties, and tunable PL emission wavelength. By coating with polyethyleneimine (PEI) of different mol. wts., blue-, yellow-, and red-emitting GQDs were successfully prepd. By TEM, at. force microscopy, and dynamic light scattering, the characterization of size and morphol. revealed that blue-emitting PEI1800 GQDs were monocoated, like jelly beans, and red-emitting PEI600 GQDs were multicoated, like capsules. The amidation reaction between carboxyl and amide functional groups played an important role in the coating process, as evidenced by IR spectroscopy and theor. calcn. with d. functional theory B3LYP/6-31G*. The PL-tunable GQDs exhibited an excellent chem. stability and extremely low cytotoxicity, and they had been shown to be feasible for bioimaging, making these GQDs highly attractive for a wide variety of applications, including multicolor imaging and bioanal.
- 37Fan, T.; Zeng, W.; Tang, W.; Yuan, C.; Tong, S.; Cai, K.; Liu, Y.; Huang, W.; Min, Y.; Epstein, A. J. Controllable Size-Selective Method to Prepare Graphene Quantum Dots from Graphene Oxide. Nanoscale Res. Lett. 2015, 10, 55 DOI: 10.1186/s11671-015-0783-937https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC2MjitFCmuw%253D%253D&md5=6d86dbb2509aaa8eb6953e007d14aaa4Controllable size-selective method to prepare graphene quantum dots from graphene oxideFan Tianju; Zeng Wenjin; Tang Wei; Yuan Chunqiu; Tong Songzhao; Cai Kaiyu; Liu Yidong; Huang Wei; Min Yong; Epstein Arthur JNanoscale research letters (2015), 10 (), 55 ISSN:1931-7573.We demonstrated one-step method to fabricate two different sizes of graphene quantum dots (GQDs) through chemical cutting from graphene oxide (GO), which had many advantages in terms of simple process, low cost, and large scale in manufacturing with higher production yield comparing to the reported methods. Several analytical methods were employed to characterize the composition and morphology of the resultants. Bright blue luminescent GQDs were obtained with a produced yield as high as 34.8%. Moreover, how the different sizes affect fluorescence wavelength mechanism was investigated in details.
- 38Abdul, G.; Zhu, X.; Chen, B. Structural Characteristics of Biochar-Graphene Nanosheet Composites and Their Adsorption Performance for Phthalic Acid Esters. Chem. Eng. J. 2017, 319, 9– 20, DOI: 10.1016/j.cej.2017.02.07438https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXktFWitLc%253D&md5=387d653175c7044a07e4a4f09bf24d3aStructural characteristics of biochar-graphene nanosheet composites and their adsorption performance for phthalic acid estersAbdul, Ghaffar; Zhu, Xiaoying; Chen, BaoliangChemical Engineering Journal (Amsterdam, Netherlands) (2017), 319 (), 9-20CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)To create more active sites on biochar surface, biochar-graphene (BG) nanosheet composites were prepd. by 1-step facile dip coating following thermal route at 3 different temps., in addn. to biochars (300, 500, 700°). The morphol. and structural compn. of biochars and BG composites were examd. by SEM, TEM, BET-N and CO2, Raman, FTIR, XPS, TGA and CHN elemental anal. It was found that graphene nanosheets (GNS, ∼1 μm, 0.1% mass) could ensure relatively higher surface area (N and CO2), porous structure and thermal stability within BG composites. BG composites portrayed the existence of GNS bearing cavities and evidently increased the graphitic structure. The adsorption capabilities of biochars and BG composites towards di-Me phthalate (DMP), di-Et phthalate (DEP), and di-Bu phthalate (DBP) as model phthalic acid esters (PAEs) were examd. by batch sorption technique. The BG composites exhibited the increased adsorption capacity comparatively to biochars. The pseudo-2nd-order kinetic rate (k2) illustrated that adsorption of PAEs was efficient and smaller mol. (DMP) was quicker to pore-diffusion mechanism. The arom. sheets of biochars and GNS on biochars dominated the π-π EDA (electron donor-acceptor) interaction for ring structure of DMP mol., whereas adsorption of DBP was attributed to hydrophobicity. The surface morphol. and compn. of biochars can be regulated with GNS to promote the adsorption capacity and kinetics for effective pollutant remediation and could be considered as promising adsorbent for various org. contaminants.
- 39Ghani, W. A. W. A. K.; Mohd, A.; da Silva, G.; Bachmann, R. T.; Taufiq-Yap, Y. H.; Rashid, U.; Al-Muhtaseb, A. H. Biochar Production from Waste Rubber-Wood-Sawdust and Its Potential Use in C Sequestration: Chemical and Physical Characterization. Ind. Crops Prod. 2013, 44, 18– 24, DOI: 10.1016/j.indcrop.2012.10.017There is no corresponding record for this reference.
- 40Das, O.; Kim, N. K.; Kalamkarov, A. L.; Sarmah, A. K.; Bhattacharyya, D. Biochar to the Rescue: Balancing the Fire Performance and Mechanical Properties of Polypropylene Composites. Polym. Degrad. Stab. 2017, 144, 485– 496, DOI: 10.1016/j.polymdegradstab.2017.09.00640https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFCqu7jF&md5=29d313e17449902923f151973c101b10Biochar to the rescue: Balancing the fire performance and mechanical properties of polypropylene compositesDas, Oisik; Kim, Nam Kyeun; Kalamkarov, Alexander L.; Sarmah, Ajit K.; Bhattacharyya, DebesPolymer Degradation and Stability (2017), 144 (), 485-496CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Biochar based wood/polypropylene (PP) composites were manufd. with two flame retardants (FRs): ammonium polyphosphate/APP and magnesium hydroxide/Mg(OH)2. The amts. of wood and biochar were alternated for accommodating the FRs in each blend. Flammability and mech. characterization for both the batches contg. different FRs were done. Having higher proportion of biochar and less wood is beneficial to reduce flammability. The thermally stable biochar contributes to formation of effective char to restrict O2 transfer into PP. The higher wt. ratio of biochar than wood in the composites compromised the tensile and flexural strengths to some extent as the APP and Mg(OH)2 particles were trapped inside biochar pores consequently reducing the effectiveness of biochar pore infiltration by PP. In general, addn. of biochar with a woody biomass (with FRs) to neat PP significantly impedes its flammability while enhancing certain mech. properties, such as flexural strength and tensile/flexural moduli and preserving the tensile strength.
- 41Vázquez-Nakagawa, M.; Rodríguez-Pérez, L.; Herranz, M. A.; Martín, N. Chirality Transfer from Graphene Quantum Dots. Chem. Commun. 2016, 52, 665– 668, DOI: 10.1039/c5cc08890a41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvVGnt7bE&md5=503b93cd7fa3e857cdfa40b6509e0dedChirality transfer from graphene quantum dotsVazquez-Nakagawa, M.; Rodriguez-Perez, L.; Herranz, M. A.; Martin, N.Chemical Communications (Cambridge, United Kingdom) (2016), 52 (4), 665-668CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Chiral graphene quantum dots were prepd. by acidic exfoliation and oxidn. of graphite, dialysis, and esterification with enantiomerically pure (R) or (S)-2-phenyl-1-propanol. CD studies support the formation of supramol. aggregates with pyrene mols., where a transfer of chirality occurs from the chiral graphene quantum dots to the pyrene.
- 42Dervishi, E.; Ji, Z.; Htoon, H.; Sykora, M.; Doorn, S. K. Raman Spectroscopy of Bottom-up Synthesized Graphene Quantum Dots: Size and Structure Dependence. Nanoscale 2019, 11, 16571– 16581, DOI: 10.1039/c9nr05345j42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhs1ahs7nO&md5=85a91fe140316a11827a49cc66afe7cfRaman spectroscopy of bottom-up synthesized graphene quantum dots: size and structure dependenceDervishi, Enkeleda; Ji, Zhiqiang; Htoon, Han; Sykora, Milan; Doorn, Stephen K.Nanoscale (2019), 11 (35), 16571-16581CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Graphene quantum dots (GQDs) have attracted significant interest as synthetically tunable optoelectronic and photonic materials that can also serve as model systems for understanding size-dependent behaviors of related graphene structures such as nanoribbons. We present a Raman spectroscopy study of bottom-up synthesized GQDs with lateral dimensions between 0.97 to 1.62 nm, well-defined (armchair) edge type, and fully benzenoid structures. For a better understanding of obsd. size-dependent trends, the study is extended to larger graphene structures including nano-graphene platelets (>25 nm) and large-area graphene. Raman spectra of GQDs reveal the presence of D and G bands, as well as higher order modes (2D, D + G, and 2G). The D and G band frequencies and intensity were found to increase as GQD size increases, while higher order modes (2D, D + G, and 2G) also increased in intensity and became more well-defined. The integrated intensity ratios of D and G bands (ID/IG) increase as the size of the GQDs approaches 2 nm and rapidly decrease for larger graphene structures. We present a quant. comparison of ID/IG ratios for the GQDs and for defects introduced into large area graphenes through ion bombardment, for which inter-defect distances are comparable to the sizes of GQDs studied here. Close agreement suggests the ID/IG ratio as a size diagnostic for other nanographenes. Finally, we show that Raman spectroscopy is also a good diagnostic tool for monitoring the formation of bottom-up synthesized GQDs.
- 43Jia, H.; Cai, Y.; Lin, J.; Liang, H.; Qi, J.; Cao, J.; Feng, J.; Fei, W. D. Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High-Potential Window Electrodes for High-Performance Supercapacitors. Adv. Sci. 2018, 5, 1700887 DOI: 10.1002/advs.20170088743https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1MbkslSntg%253D%253D&md5=95d3a762e41e864320db28ce54057244Heterostructural Graphene Quantum Dot/MnO2 Nanosheets toward High-Potential Window Electrodes for High-Performance SupercapacitorsJia Henan; Cai Yifei; Lin Jinghuang; Liang Haoyan; Qi Junlei; Cao Jian; Feng Jicai; Fei WeiDongAdvanced science (Weinheim, Baden-Wurttemberg, Germany) (2018), 5 (5), 1700887 ISSN:2198-3844.The potential window of aqueous supercapacitors is limited by the theoretical value (≈1.23 V) and is usually lower than ≈1 V, which hinders further improvements for energy density. Here, a simple and scalable method is developed to fabricate unique graphene quantum dot (GQD)/MnO2 heterostructural electrodes to extend the potential window to 0-1.3 V for high-performance aqueous supercapacitor. The GQD/MnO2 heterostructural electrode is fabricated by GQDs in situ formed on the surface of MnO2 nanosheet arrays with good interface bonding by the formation of Mn-O-C bonds. Further, it is interesting to find that the potential window can be extended to 1.3 V by a potential drop in the built-in electric field of the GQD/MnO2 heterostructural region. Additionally, the specific capacitance up to 1170 F g(-1) at a scan rate of 5 mV s(-1) (1094 F g(-1) at 0-1 V) and cycle performance (92.7%@10 000 cycles) between 0 and 1.3 V are observed. A 2.3 V aqueous GQD/MnO2-3//nitrogen-doped graphene ASC is assembled, which exhibits the high energy density of 118 Wh kg(-1) at the power density of 923 W kg(-1). This work opens new opportunities for developing high-voltage aqueous supercapacitors using in situ formed heterostructures to further increase energy density.
- 44Liu, J.; Zhou, Y.; Xie, Z.; Li, Y.; Liu, Y.; Sun, J.; Ma, Y.; Terasaki, O.; Chen, L. Conjugated Copper–Catecholate Framework Electrodes for Efficient Energy Storage. Angew. Chem., Int. Ed. 2020, 59, 1081– 1086, DOI: 10.1002/anie.20191264244https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVajsr3E&md5=0f7e7b653ecffda622dd412d203e2f4bConjugated Copper-Catecholate Framework Electrodes for Efficient Energy StorageLiu, Jingjuan; Zhou, Yi; Xie, Zhen; Li, Yang; Liu, Yunpeng; Sun, Jie; Ma, Yanhang; Terasaki, Osamu; Chen, LongAngewandte Chemie, International Edition (2020), 59 (3), 1081-1086CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A conjugated copper(II) catecholate based metal-org. framework (namely Cu-DBC) was prepd. using a D2-sym. redox-active ligand in a copper bis(dihydroxy) coordination geometry. The π-d conjugated framework exhibits typical semiconducting behavior with a high elec. cond. of ca. 1.0 S m-1 at room temp. Benefiting from the good elec. cond. and the excellent redox reversibility of both ligand and copper centers, Cu-DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g-1 at a discharge rate of 0.2 A g-1. Moreover, the sym. solid-state supercapacitor of Cu-DBC exhibits high areal (879 mF cm-2) and volumetric (22 F cm-3) capacitances, as well as good rate capability. These metrics are superior to most reported MOF-based supercapacitors, demonstrating promising applications in energy-storage devices.
- 45Luo, J.; Wang, J.; Liu, S.; Wu, W.; Jia, T.; Yang, Z.; Mu, S.; Huang, Y. Graphene Quantum Dots Encapsulated Tremella-like NiCo2O4 for Advanced Asymmetric Supercapacitors. Carbon 2019, 146, 1– 8, DOI: 10.1016/j.carbon.2019.01.07845https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisFCrsbc%253D&md5=18e298c7c1e5086fd82833e884410a60Graphene quantum dots encapsulated tremella-like NiCo2O4 for advanced asymmetric supercapacitorsLuo, Jiahuan; Wang, Jing; Liu, Sen; Wu, Weiming; Jia, Taixuan; Yang, Ze; Mu, Shichun; Huang, YunhuiCarbon (2019), 146 (), 1-8CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)A tremella-like NiCo2O4@graphene quantum dots (GQDs) composite is prepd. where the tremella-like NiCo2O4 is homogeneously encapsulated by GQDs. Herein, the GQDs based on π-conjugated core with abundant edge sites, make NiCo2O4 favorable for advanced elec. energy storage (EES). In terms of the synergistic effect between the conductive GQDs and tremella-like NiCo2O4, the as prepd. NiCo2O4@GQDs composite exhibits an excellent specific capacitance of 1242 F g-1 at 30 A g-1 in 2.0 M KOH electrolytes, much higher than that of pristine NiCo2O4 (790 F g-1 at 30 A g-1). Also, it manifests outstanding cycle stability (99% capacitance retention after 4000 cycles). Furthermore, an asym. supercapacitor (ASC) is assembled by pairing NiCo2O4@GQDs composite as pos. electrode and activated carbon (AC) as neg. electrode (NiCo2O4@GQDs//AC), and its specific energy d. is as high as 38 W h kg-1 at a power d. of 800 W kg-1.
- 46El-Kady, M. F.; Strong, V.; Dubin, S.; Kaner, R. B. Laser Scribing of High-Performance and Flexible Graphene-Based Electrochemical Capacitors. Science 2012, 335, 1326– 1330, DOI: 10.1126/science.121674446https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xjs1Smurw%253D&md5=301781d36eac2b361aa04ddafb874cecLaser Scribing of High-Performance and Flexible Graphene-Based Electrochemical CapacitorsEl-Kady, Maher F.; Strong, Veronica; Dubin, Sergey; Kaner, Richard B.Science (Washington, DC, United States) (2012), 335 (6074), 1326-1330CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Although electrochem. capacitors (ECs), also known as supercapacitors or ultracapacitors, charge and discharge faster than batteries, they are still limited by low energy densities and slow rate capabilities. The authors used a std. LightScribe DVD optical drive to do the direct laser redn. of graphite oxide films to graphene. The produced films are mech. robust, show high elec. cond. (1738 S per m) and sp. surface area (1520 square meters per g), and can thus be used directly as EC electrodes without the need for binders or current collectors, as is the case for conventional ECs. Devices made with these electrodes exhibit ultrahigh energy d. values in different electrolytes while maintaining the high power d. and excellent cycle stability of ECs. Also, these ECs maintain excellent electrochem. attributes under high mech. stress and thus hold promise for high-power, flexible electronics.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsaelm.1c00487.
(a) GD dispersion in normal light and 365 nm UV light; (b) height profile of GDs from AFM; (c) size distribution histogram of GDs based on AFM image (Figure S1); results from elemental analysis, EDX spectra of (a) pristine KLCA60 and (b) GD-doped KLCA60 (Figure S2); electrochemical parameters of carbon aerogels and GD-doped carbon aerogels based on cyclic voltammetry (CV) curves (Table S1); electrochemical properties of carbon aerogels and GDs-incorporated carbon aerogels based on galvanostatic charge–discharge (GCD) curves (Table S2); (a) schematic representation of supercapacitor (SC) assembly; (b) equivalent circuit for electrode interface fitted using ZView software showing equivalent series resistance (RESR), double-layer capacitance (CEDL), charge-transfer resistance (RCT), constant phase element (CPE) representing pseudocapacitance along with faradaic resistance (RF); (c) experimental and fitted Nyquist plots; and (d) experimental and fitted |Z| vs frequency plots for the supercapacitor demonstrating good fitting of equivalent circuit with SC (Figure S3); EIS parameters obtained after fitting the equivalent circuit using ZView (Table S3); capacitance retention for the GD-doped KLCA60 electrode after 3000 cycles in the cyclic stability measurements using three-electrode system at 3 A g–1; inset showing the charge–discharge cycles for 2990–3000 cycles; Trasatti method (Figure S4) (PDF)
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