2D Material-Based Surface-Enhanced Raman Spectroscopy Platforms (Either Alone or in Nanocomposite Form)─From a Chemical Enhancement PerspectiveClick to copy article linkArticle link copied!
- Dipanwita Majumdar*Dipanwita Majumdar*Email: [email protected]Satyendra Nath Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, IndiaMore by Dipanwita Majumdar
Abstract
Surface-enhanced Raman spectroscopy (SERS) is a vibrational spectroscopic technique with molecular fingerprinting capability and high sensitivity, even down to the single-molecule level. As it is 50 years since the observation of the phenomenon, it has now become an important task to discuss the challenges in this field and determine the areas of development. Electromagnetic enhancement has a mature theoretical explanation, while a chemical mechanism which involves more complex interactions has been difficult to elucidate until recently. This article focuses on the 2D material-based platforms where chemical enhancement (CE) is a significant contributor to SERS. In the context of a diverse range (transition metal dichalcogenides, MXenes, etc.) and categories (insulating, semiconducting, semimetallic, and metallic) of 2D materials, the review aims to realize the influence of various factors on SERS response such as substrates (layer thickness, structural phase, etc.), analytes (energy levels, molecular orientation, etc.), excitation wavelengths, molecular resonances, charge-transfer transitions, dipole interactions, etc. Some examples of special treatments or approaches have been outlined for overcoming well-known limitations of SERS and include how CE benefits from the defect-induced physicochemical changes to 2D materials mostly via the charge-transport ability or surface interaction efficiency. The review may help readers understand different phenomena involved in CE and broaden the substrate-designing approaches based on a diverse set of 2D materials.
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Special Issue
Published as part of ACS Omega special issue “Celebrating 50 Years of Surface Enhanced Spectroscopy”.
1. Introduction
Figure 1
Figure 1. Timeline of the crucial events contributed significantly to the advancement and realization of the SERS technique.
Figure 2
Figure 2. Schematic illustration of the EM and CE mechanism of SERS.
2. Challenges with Noble-Metal-Based SERS Substrates
3. Results and Discussion
3.1. 2D Materials Alone
Figure 3
Figure 3. (A) Raman spectra of the CuPc (2 Å) molecule on the blank SiO2/Si substrate (black line), graphene (blue line), h-BN (red line), and MoS2 (green line) substrates. The numbers marked on the peaks are the peak frequencies of the Raman signals from the CuPc molecule. For all of the spectra, the baseline correction was removed to have a better comparison. (B) Optical image of a h-BN flake. Some h-BN flakes are marked by arrows or by a red dashed ring. (C) Raman mapping image for the CuPc vibrational mode at 1531 cm–1 corresponding to (B). Reprinted with permission from ref (33). Copyright 2014 American Chemical Society.
3.1.1. Impact of Molecular Orientation
3.1.2. Photostability of the Probes
3.1.3. Structural Phase and DOS
3.2. Metal–2D Material Nanohybrids
Figure 4
Figure 4. (A) Schematic illustration of synthesizing the AuNPs@MoS2 nanocomposite. TEM images of (B) MoS2 and (C–G) AuNPs@MoS2 nanocomposites. Reprinted with permission from ref (120). Copyright 2014 American Chemical Society.
3.2.1. Attempts toward Chemical Stability
Figure 5
Figure 5. (A) Schematic illustration of the CT process among S-g-C3N4, O2, and Ag. The label δ denotes the negative charge of the Ag surface or S-g-C3N4. (B) TEM image of the S-g-C3N4/Ag hybrid. (A,B) Reprinted with permission from ref (43). Copyright 2016 the author(s).
3.3. Special Treatments of 2D Materials toward SERS
3.3.1. Impact of Defects and Doping
Figure 6
Figure 6. (A) Raman profile of R6G (10–6 M) on substrates deposited with an unincorporated MoS2 sample, hydrothermally treated oxygen-substituted MoS2 sample at 200 °C, partially oxidized sample at 300 °C for 40 min, completely oxidized MoO3 sample, and bare SiO2/Si. (B) Energy-level diagrams illustrating the electronic transitions. The calculated band structures of MoS2 (a) and MoSxOy (b) taking the Fermi level as a reference. Schematic energy-level diagrams of R6G on (c) MoSxOy and (d) MoS2 and MoO3 with respect to the vacuum level. (C) Raman spectra of 10–5, 10–6, 10–7, and 10–8 M RhB on PdSe2. (D) Energy band diagram showing the CT pathways in the RhB/PdSe2 hybrid system. (A,B) Reprinted with permission from ref (138). Copyright 2017 the author(s). (C,D) Reprinted with permission from ref (141). Copyright 2023 the author(s).
3.3.2. Surface Treatments
3.4. Homo- or Mixed-Dimensional Composites of 2D Materials in SERS
3.5. MXenes as Candidates for SERS Substrates
3.5.1. MXenes Alone
3.5.2. Metal–MXene Nanohybrids
Figure 7
Figure 7. (A) Graphical representation of in situ one-step solution processing synthesis of Ag, Au, and Pd@MXene (Ti3C2Tx) hybrids by soft-solution processing via a sonochemical approach. (B) Raman spectrum of Ti3C2Tx after soaking in MB dispersed in ethanol and subsequent drying. SERS spectra of MB with (b) Ag@, (c) Au@, and (d) Pd@MXene. Reprinted with permission from ref (169). Copyright 2016 the author(s).
Figure 8
Figure 8. (a,b) SEM images of a Ti3AlC2 bulk structure (a) and Ti3C2 MXene (b). (c,d) TEM images, HRTEM images, and the corresponding SAED patterns (inset in the HRTEM images) of Ti3C2 MXene (c) and Au–Ti3C2 (d). (e,f) SERS spectra of 4-MBA, MeB, and MV powder; SERS spectra of the mixed solution with 10–5 M 4-MBA, MV, and MeB on Ti3C2 (e) and Au–Ti3C2 (f) substrates with different excitation lasers of 532, 633, and 785 nm. Reprinted with permission from ref (174). Copyright 2020 the author(s).
Figure 9
Figure 9. (a) SEM micrographs of the r-Ti3C2Tx powder. (b) Tapping mode AFM image of Ti3C2Tx nanosheets on SiO2/Si. (c) XRD patterns of the Ti3AlC2 MAX phase (black), Ti3C2Tx (red), and r-Ti3C2Tx (blue). SERS spectra of the probe molecules: (d) crystal violet at 2 × 10–6 M, (e) MB at 1 × 10–6 M, and (f) rhodamine 6G (R6G) at 1 × 10–7 M, respectively, collected on Ti3C2Tx/SiO2/Si (black) and r-Ti3C2Tx/SiO2/Si (red) substrates. Used with permission of The Royal Society of Chemistry, from ref (179); permission conveyed through Copyright Clearance Center, Inc.
4. Mechanisms behind CEs
5. Conclusions
Acknowledgments
This work was supported by the Department of Science and Technology, Govt. of India (DST/INSPIRE/04/2016/002377).
References
This article references 183 other publications.
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- 3Albrecht, M. G.; Creighton, J. A. Anomalously Intense Raman Spectra of Pyridine at a Silver Electrode. J. Am. Chem. Soc. 1977, 99, 5215– 5217, DOI: 10.1021/ja00457a071Google Scholar3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXkslKjsb4%253D&md5=94e6c8e0977783c4d4ef4fa778a6d683Anomalously intense Raman spectra of pyridine at a silver electrodeAlbrecht, M. Grant; Creighton, J. AlanJournal of the American Chemical Society (1977), 99 (15), 5215-17CODEN: JACSAT; ISSN:0002-7863.Raman bands due to pyridine absorbed at a Ag electrode, which are absent for a freshly cleaned electrode immersed in aq. pyridine/KCl, are anomalously intense after a single electrochem. roughening cycle. The intensity enhancement is estd. to be ∼105-fold, and is possibly due to a resonance Raman effect in pyridine induced by an electronic interaction with the roughened metal surface. The high intensity of Raman bands enables changes in the surface concn. of absorbed pyridine to be readily followed during and after the roughening cycle.
- 4Moskovits, M. Surface Roughness and the Enhanced Intensity of Raman Scattering by Molecules Adsorbed on Metals. J. Chem. Phys. 1978, 69, 4159– 4161, DOI: 10.1063/1.437095Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXht1OhtQ%253D%253D&md5=16d496023b0831f1c07a9f83fb7f80ffSurface roughness and the enhanced intensity of Raman scattering by molecules adsorbed on metalsMoskovits, M.Journal of Chemical Physics (1978), 69 (9), 4159-61CODEN: JCPSA6; ISSN:0021-9606.It is proposed that the anomalous intensity arises from preresonant or resonant excitations of conduction electron resonances in adsorbate covered metal bumps on the surface. The bumps form a 2-dimensional colloidlike layer which displays a collective resonance at a frequency which depends on the bump d. The model can account for the disparate excitation functions reported in terms of varying degrees of roughness. The apparent lack of enhancement with metals other than Group IB is also explained.
- 5Stiles, P. L.; Dieringer, J. A.; Shah, N. C.; Van Duyne, R. P. Surface-enhanced Raman spectroscopy. Annu. Rev. Anal. Chem. 2008, 1, 601– 626, DOI: 10.1146/annurev.anchem.1.031207.112814Google Scholar5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtFygsLzJ&md5=993c957096ba93ca702d7b754cae7d7fSurface-enhanced Raman spectroscopyStiles, Paul L.; Dieringer, Jon A.; Shah, Nilam C.; Van Duyne, Richard P.Annual Review of Analytical Chemistry (2008), 1 (), 601-626CODEN: ARACFU; ISSN:1936-1327. (Annual Reviews Inc.)A review. The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing anal. tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithog. for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several expts. that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chem. warfare agents and several biol. mols.
- 6Baik, S. Y.; Cho, Y. J.; Lim, Y. R.; Im, H. S.; Jang, D. M.; Myung, Y.; Park, J.; Kang, H. S. Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell Nanowires. ACS Nano 2012, 6, 2459– 2470, DOI: 10.1021/nn204797bGoogle Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvFahtbY%253D&md5=df0dd1abe969498ebb7599a4a1705ca3Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell NanowiresBaik, Sun Young; Cho, Yong Jae; Lim, Young Rok; Im, Hyung Soon; Jang, Dong Myung; Myung, Yoon; Park, Jeunghee; Kang, Hong SeokACS Nano (2012), 6 (3), 2459-2470CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The deposition of silver (Ag) or gold (Au) nanoparticles (NPs) on vertically aligned silicon-carbon (Si-C) core-shell nanowires (NWs) produces sensitive substrates for surface-enhanced Raman spectroscopy (SERS). The undoped and 30% nitrogen (N)-doped graphitic layers of the C shell (avg thickness of 20 nm) induce a higher sensitivity toward neg. (-) and pos. ( + ) charged dye mols., resp., showing remarkable charge selectivity. The Ag NPs exhibit higher charge selectivity than the Au NPs. The Ag NPs deposited on p- and n-type Si NWs also exhibit (-) and ( + ) charge selectivity, resp., which is higher than that of the Au NPs. The XPS anal. indicates that the N-doped graphitic layers donate more electrons to the metal NPs than the undoped ones. More distinct electron transfer occurs to the Ag NPs than to the Au NPs. First principles calcns. of the graphene-metal adducts suggest that the large electron transfer capacity of the N-doped graphitic layers is due to the formation of a N→Ag coordinate bond involving the lone pair electrons of the N atoms. Probably the more (-) charged NPs on the N-doped graphitic layers prefer the adsorption of ( + ) charged dyes, enhancing the SERS intensity. The charge selectivity of the Si NW substrates can also be rationalized by the greater electron transfer from the n-type Si to the metal NPs.
- 7Liu, D.; Zhou, F.; Li, C.; Zhang, T.; Zhang, H.; Cai, W.; Li, Y. Black Gold: Plasmonic colloidosomes with broadband absorption self-assembled from monodispersed gold nanospheres by using a reverse emulsion system. Angew. Chem., Int. Ed. 2015, 54, 9596– 9600, DOI: 10.1002/anie.201503384Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVKmsL7O&md5=2d5cf6067b1223e3c5801cd79ef24ad1Black Gold: Plasmonic Colloidosomes with Broadband Absorption Self-Assembled from Monodispersed Gold Nanospheres by Using a Reverse Emulsion SystemLiu, Dilong; Zhou, Fei; Li, Cuncheng; Zhang, Tao; Zhang, Honghua; Cai, Weiping; Li, YueAngewandte Chemie, International Edition (2015), 54 (33), 9596-9600CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A facile approach for the fabrication of black plasmonic colloidosomes assembled from Au nanospheres is developed by an emulsion-templating strategy. This self-assembly process is based on a reverse water-in-1-butanol emulsion system, in which the water emulsion droplets can dissolve into 1-butanol (oil) phase at an appropriate rate. These Au colloidosomes possess hcp. multilayer shells and show a low reflectivity and intense broadband absorption owing to the strong interparticle plasmonic coupling, which is further investigated by a finite-difference time-domain method. This method is universal and is suitable for self-assembly of different noble-metal nanoparticles into different colloidosomes.
- 8Otto, A. The ‘chemical’ (electronic) contribution to surface-enhanced Raman scattering. J. Raman Spectrosc. 2005, 36, 497– 509, DOI: 10.1002/jrs.1355Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXntVansLw%253D&md5=03c548c51d30907fd154f651b3194a55The 'chemical' (electronic) contribution to surface-enhanced Raman scatteringOtto, AndreasJournal of Raman Spectroscopy (2005), 36 (6/7), 497-509CODEN: JRSPAF; ISSN:0377-0486. (John Wiley & Sons Ltd.)The model of surface-enhanced Raman scattering (SERS) by time-dependent evolution in the intermediate anionic state of the adsorbate is analogous to intramol. Franck-Condon resonance Raman scattering. For adsorbates with a π* state, the residence time of some femtoseconds (10-15 s) in the anionic state leads to a sepn. of electron (e) and hole (h), which quenches SERS at a smooth surface. At so-called SERS-active sites, the residence time of the hole is enhanced, and there is no final e-h pair and the excitation of only a mol. vibration leads to SERS. But for mols. with only high-energy σ* states, the residence time in the anionic state is <1 fs (analogous to the impulse mechanism in electron scattering), and the creation of e-h pairs is less likely. This leads to 1st-layer electronic Raman scattering, esp. by C-H stretch vibrations with an av. enhancement of ∼30-40-fold.
- 9Persson, B. N. J.; Zhao, K.; Zhang, Z. Y. Chemical contribution to surface-enhanced Raman scattering. Phys. Rev. Lett. 2006, 96, 207401, DOI: 10.1103/PhysRevLett.96.207401Google Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XltVOju7Y%253D&md5=579010b2a2a7c89e007cf16b053d0c60Chemical Contribution to Surface-Enhanced Raman ScatteringPersson, B. N. J.; Zhao, Ke; Zhang, ZhenyuPhysical Review Letters (2006), 96 (20), 207401/1-207401/4CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)We present a new mechanism for the chem. contribution to surface-enhanced Raman scattering (SERS). The theory considers the modulation of the polarizability of a metal nanocluster or a flat metal surface by the vibrational motion of an adsorbed mol. The modulated polarization of the substrate coupled with the incident light will contribute to the Raman scattering enhancement. We show that for a metal cluster and for a flat metal surface this new chem. contribution may enhance the Raman scattering intensity by a factor of ∼102 and ∼104, resp. The new SERS process is detd. by the elec. field parallel to the surface of the metal substrate at the mol. binding site.
- 10Morton, S. M.; Jensen, L. Understanding the Molecule–Surface Chemical Coupling in SERS. J. Am. Chem. Soc. 2009, 131 (11), 4090– 4098, DOI: 10.1021/ja809143cGoogle Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXisFamtLw%253D&md5=6feb18059f8e9abdb86ff2150d420cdbUnderstanding the Molecule-Surface Chemical Coupling in SERSMorton, Seth M.; Jensen, LasseJournal of the American Chemical Society (2009), 131 (11), 4090-4098CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The enhancement mechanism due to the mol.-surface chem. coupling in surface-enhanced Raman scattering (SERS) was characterized using time-dependent d. functional theory. This was achieved with a systematical study of the chem. enhancement of meta- and para-substituted pyridines interacting with a small silver cluster (Ag20). Changing the functional groups on pyridine enabled one to modulate the direct chem. interactions between the pyridine ring and the metal cluster. Surprisingly, the enhancement does not increase as more charge is transferred from the pyridine ring to the cluster. Instead, the magnitude of chem. enhancement is governed to a large extent by the energy difference between the highest occupied energy level (HOMO) of the metal and the lowest unoccupied energy level (LUMO) of the mol. The enhancement scales roughly as (ωX/‾ωe)4, where ‾ωe is an av. excitation energy between the HOMO of the metal and the LUMO of the mol. and ωX is the HOMO-LUMO gap of the free mol. The trend was verified by considering substituted benzenethiols, small mols., and silver clusters of varying sizes. The results imply that mols. that show significant stabilization of the HOMO-LUMO gaps (such as those that readily accept π-backbonding) would be likely to have strong chem. enhancement. The findings presented here provide the framework for designing new mols. which exhibit high chem. enhancements. However, it remains a challenge to accurately describe the magnitude of the Raman enhancements using electronic structure methods, esp. d. functional theory, because they often underestimate the energy gap.
- 11Creighton, J. A.; Blatchford, C. G.; Albrecht, M. G. Plasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelength. J. Chem. Soc., Faraday Trans. 2 1979, 75, 790– 798, DOI: 10.1039/f29797500790Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXlsFKrtLk%253D&md5=06880d68306c8b44a81ccd60896898ebPlasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelengthCreighton, J. Alan; Blatchford, Christopher G.; Albrecht, M. GrantJournal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics (1979), 75 (5), 790-8CODEN: JCFTBS; ISSN:0300-9238.The enhancement of the Raman-scattering intensity of pyridine mols. adsorbed on Ag or Au sols. of particle size similar to the excitation wavelength was examd. The degree of enhancement was greatest for excitation at the wavelength of the Mie extinction max. of the metal particles. A new resonance-Raman phenomenon is proposed in which the polarizability of the metal particles is modulated by vibrations of adsorbed mols. Surface plasma oscillations are involved in the intense Raman scattering by metals adsorbed on rough Ag surfaces. The metal dielec.-function requirements for resonant Mie scattering enable the excitation wavelength for plasma-resonance enhancement of Raman scattering by mols. adsorbed on other metals to be estd.
- 12Hildebrandt, P.; Stockburger, M. Surface-Enhanced Resonance Raman Spectroscopy of Rhodamine 6G Adsorbed on Colloidal Silver. J. Phys. Chem. 1984, 88, 5935– 5944, DOI: 10.1021/j150668a038Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2cXmtFyrsr8%253D&md5=c4629b5f47502c5374d8430ff211a61eSurface-enhanced resonance Raman spectroscopy of Rhodamine 6G adsorbed on colloidal silverHildebrandt, Peter; Stockburger, ManfredJournal of Physical Chemistry (1984), 88 (24), 5935-44CODEN: JPCHAX; ISSN:0022-3654.Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal Ag was studied. Adsorption isotherms could be obtained from SERRS and fluorescent measurements. Two different kinds of adsorption sites were inferred from the isotherms. One kind is rather unspecific and shows a high surface coverage. The enhancement factor at such sites is 3000, which can be well explained by the classical electromagnetic theory of colloids. The 2nd kind is only obsd. in the presence of anions (Cl-, I-, Br-, F-, SO42-). Specific active sites are formed at an extremely low surface coverage. From the isotherms at such sites the mols. are chemisorbed. Overall enhancement factors up to 106 were found for mols. at anion-activated sites. The addnl. enhancement factor is ascribed to a local mechanism of an R6G-adatom (or cluster)-anion surface complex. SERRS excitation profiles of active sites are closely related to the mol. resonance at 530 nm. SERRS spectra of R6G were recorded and analyzed in a wide frequency range. The 2 adsorption sites could be distinguished by characteristic vibrational features. It was demonstrated that SERRS is also a powerful anal. tool for dye mols.
- 13Michaels, A. M.; Nirmal, M.; Brus, L. Surface enhanced Raman spectroscopy of individual Rhodamine 6G molecules on large Ag nanocrystals. J. Am. Chem. Soc. 1999, 121 (43), 9932– 9939, DOI: 10.1021/ja992128qGoogle Scholar13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXmsFejs7c%253D&md5=e50bc2e15f5de8b3d2807e776092dfccSurface Enhanced Raman Spectroscopy of Individual Rhodamine 6G Molecules on Large Ag NanocrystalsMichaels, Amy M.; Nirmal, M.; Brus, L. E.Journal of the American Chemical Society (1999), 121 (43), 9932-9939CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)To explore the relation between local electromagnetic field enhancement and the large SERS (surface enhanced Raman scattering) enhancement that enables the observation of single mol. Raman spectra, the authors measure both resonant Rayleigh scattering spectra and rhodamine 6G Raman spectra from single Ag particles. The authors' app. combines the techniques of dark-field optical microscopy for resonant Rayleigh measurements, and grazing incidence Raman spectroscopy. The Rayleigh spectra show that the citrate-reduced Ag colloid is extremely heterogeneous. Only the larger particles, in part created by salt induced aggregation, show a large SERS effect. In agreement with the work of Nie and Emory, a few nanocrystals show huge single mol. R6G SERS intensities. While all SERS active particles have some resonant Rayleigh scattering at the 514.5 nm laser wavelength, there is no correlation between the resonant Rayleigh spectra and the SERS intensity. The authors discuss a model in which huge SERS intensities result from single chemisorbed mols. interacting with ballistic electrons in optically excited large Ag particles. This model is a natural consequence of the std. local electromagnetic field model for SERS and the high surface sensitivity of plasmon dephasing in the noble metals.
- 14Yang, Y.; Li, Z. Y.; Yamaguchi, K.; Tanemura, M.; Huang, Z. R.; Jiang, D.; Chen, Y.; Zhou, F.; Nogami, M. Controlled fabrication of silver nanoneedles array for SERS and their application in rapid detection of narcotics. Nanoscale 2012, 4 (8), 2663– 2669, DOI: 10.1039/c2nr12110gGoogle ScholarThere is no corresponding record for this reference.
- 15Guselnikova, O.; Nugraha, A. S.; Na, J.; Postnikov, P.; Kim, H.-J.; Plotnikov, E.; Yamauchi, Y. Surface Filtration in Mesoporous Au Films Decorated by Ag Nanoparticles for Solving SERS Sensing Small Molecules in Living Cells. ACS Appl. Mater. Interfaces 2022, 14 (36), 41629– 41639, DOI: 10.1021/acsami.2c12804Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xit1Kjs7nI&md5=5a83f2eedadeb4912b43ce69a42a4471Surface Filtration in Mesoporous Au Films Decorated by Ag Nanoparticles for Solving SERS Sensing Small Molecules in Living CellsGuselnikova, Olga; Nugraha, Asep Sugih; Na, Jongbeom; Postnikov, Pavel; Kim, Hyun-Jong; Plotnikov, Evgenii; Yamauchi, YusukeACS Applied Materials & Interfaces (2022), 14 (36), 41629-41639CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)For surface-enhanced Raman spectroscopy (SERS) sensing of small mols. in the presence of living cells, biofouling and blocking of plasmonic centers are key challenges. Here, we have developed a mesoporous Au (AuM) film coated with a Ag nanoparticles (NPs) as a plasmonic sensor (AuM@Ag) to analyze arom. thiols, which is an example of a small mol., in the presence of a living cell strain (e.g., MDA-MB-231) as a model living system. The resulting AuM@Ag provides 0.1 nM sensitivity and high reproducibility for thiols sensing. Simultaneously, the AuM@Ag film filters large biomols., preventing Raman signals from overlapping produced by large biomols. After anal., the AuM@Ag film undergoes recycling by the full dissoln. of the Ag-thiol layer and removal of thiols from AuM. Furthermore, fresh AgNPs are formed for further SERS anal., which circumvents the Ag oxidn. issue. The ease of the AgNPs deposition allows up to 12 cycles of on-demand recycling and sensing even after utilization as a sensor in multicomponent media without enhancement and sensitivity loss. The reported mesoporous film with surface filtering ability and prominent recycling procedure promises to offer a new strategy for the detection of various small mols. in the presence of living cells.
- 16Yao, X.; Jiang, S.; Luo, S.; Liu, B. W.; Huang, T. X.; Hu, S.; Zhu, J.; Wang, X.; Ren, B. Uniform Periodic Bowtie SERS Substrate with Narrow Nanogaps Obtained by Monitored Pulsed Electrodeposition. ACS Appl. Mater. Interfaces 2020, 12 (32), 36505– 36512, DOI: 10.1021/acsami.0c09357Google Scholar16https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVSmsL3J&md5=d4f438d0d8c87955f02b0f8b17f074cdUniform Periodic Bowtie SERS Substrate with Narrow Nanogaps Obtained by Monitored Pulsed ElectrodepositionYao, Xu; Jiang, Shan; Luo, Songsong; Liu, Bo-Wen; Huang, Teng-Xiang; Hu, Shu; Zhu, Jinfeng; Wang, Xiang; Ren, BinACS Applied Materials & Interfaces (2020), 12 (32), 36505-36512CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive technique with mol. specificity, making it an ideal anal. tool in various fields. However, the breadth of practical applications of SERS has been severely limited because it is still a great challenge to achieve simultaneously a high sensitivity and a high reproducibility. Herein, we report a highly controllable method to fabricate periodic bowtie SERS substrates with a narrow nanogap, high SERS enhancement, and good uniformity over a large area. The periodic bowtie template is first fabricated over a gold film by holog. lithog. (HL), followed by Au deposition to obtain a conductive plasmonic bowtie array. The gap size is then narrowed down by pulsed electrodeposition of Ag simultaneously monitored in situ by electrochem. dark field spectroscopy. Thus, we are able to observe the most sensitive change in the scattering spectra when the gap is just about to merge and obtain uniform SERS substrates with a gap size down to around 5 nm. The av. enhancement factor of 5 x 107 to 1 x 108 is obtained, which is 50 times larger than that from Au nanoparticle-assembled substrates and 140 times larger than that from com. Klarite chips. This substrate offers a promising opportunity for SERS practical applications.
- 17Nie, S.; Emory, S. R. Probing single molecules and single nanoparticles by surface-enhanced Raman scattering. Science 1997, 275 (5303), 1102– 1106, DOI: 10.1126/science.275.5303.1102Google Scholar17https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXhtlGlsL4%253D&md5=e8968fee3a48e1f3131e8bebcc40e2b0Probing single molecules and single nanoparticles by surface-enhanced Raman scatteringNie, Shuming; Emory, Steven R.Science (Washington, D. C.) (1997), 275 (5303), 1102-1106CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Optical detection and spectroscopy of single mols. and single nanoparticles were achieved at room temp. using surface-enhanced Raman scattering. Individual Ag colloidal nanoparticles were screened from a large heterogeneous population for special size-dependent properties and were then used to amplify the speculation for special size-dependent properties and were then used to amplify the spectroscopic signatures of adsorbed mols. For single rhodamine 6G mols. adsorbed on the selected nanoparticles, the intrinsic Raman enhancement factors were ∼1014 to 1015, much larger than the ensemble-averaged values derived from conventional measurements. This enormous enhancement leads to vibrational Raman signals that are more intense and more stable than single-mol. fluorescence.
- 18Kneipp, K.; Wang, Y.; Kneipp, H.; Perelman, L. T.; Itzkan, I.; Dasari, R. R.; Feld, M. S. Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS). Phys. Rev. Lett. 1997, 78, 1667– 1670, DOI: 10.1103/PhysRevLett.78.1667Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2sXhsV2jtb4%253D&md5=836f50582094886bb2c3b607c06b1408Single molecule detection using surface-enhanced Raman scattering (SERS)Kneipp, Katrin; Wang, Yang; Kneipp, Harald; Perelman, Lev T.; Itzkan, Irving; Dasari, Ramachandra R.; Feld, Michael S.Physical Review Letters (1997), 78 (9), 1667-1670CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)By exploiting the extremely large effective cross sections (10-17-10-16 cm2/mol.) available from surface-enhanced Raman scattering (SERS), the authors achieved the 1st observation of single mol. Raman scattering. Measured spectra of a single crystal violet mol. in aq. colloidal Ag soln. using one 2nd collection time and ∼2 × 105 W/cm2 nonresonant near-IR excitation show a clear fingerprint of its Raman features between 700 and 1700 cm-1. Spectra obsd. in a time sequence for an av. of 0.6 dye mol. in the probed vol. exhibited the expected Poisson distribution for actually measuring 0, 1, 2, or 3 mols.
- 19Petryayeva, E.; Krull, U. J. Localized surface plasmon resonance: nanostructures, bioassays and biosensing-a review. Anal. Chim. Acta 2011, 706, 8– 24, DOI: 10.1016/j.aca.2011.08.020Google Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtlemsbjM&md5=b298d4394739737ea8c3d950052924dfLocalized surface plasmon resonance: Nanostructures, bioassays and biosensing-A reviewPetryayeva, Eleonora; Krull, Ulrich J.Analytica Chimica Acta (2011), 706 (1), 8-24CODEN: ACACAM; ISSN:0003-2670. (Elsevier B.V.)A review. Localized surface plasmon resonance (LSPR) is an optical phenomena generated by light when it interacts with conductive nanoparticles (NPs) that are smaller than the incident wavelength. As in surface plasmon resonance, the elec. field of incident light can be deposited to collectively excite electrons of a conduction band, with the result being coherent localized plasmon oscillations with a resonant frequency that strongly depends on the compn., size, geometry, dielec. environment and sepn. distance of NPs. This review serves to describe the phys. theory of LSPR formation at the surface of nanostructures, and the potential for this optical technol. to serve as a basis for the development bioassays and biosensing of high sensitivity. The benefits and challenges assocd. with various exptl. designs of nanoparticles and detection systems, as well as creative approaches that have been developed to improve sensitivity and limits of detection are highlighted using examples from the literature.
- 20Kelly, K. L.; Coronado, E.; Zhao, L. L.; Schatz, G. C. The optical properties of metal nanoparticles: the influence of size, shape, and dielectric environment. J. Phys. Chem. B 2003, 107, 668– 677, DOI: 10.1021/jp026731yGoogle Scholar20https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38Xps1Ghur0%253D&md5=f7be29b07a5f0d8311d7f0042f359274The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric EnvironmentKelly, K. Lance; Coronado, Eduardo; Zhao, Lin Lin; Schatz, George C.Journal of Physical Chemistry B (2003), 107 (3), 668-677CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)The optical properties of metal nanoparticles have long been of interest in phys. chem., starting with Faraday's studies of colloidal Au in the middle 1800s. More recently, new lithog. techniques as well as improvements to classical wet chem. methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielec. environments. In this feature article, the authors describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qual. features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of anal. and numerical methods for calcg. extinction and scattering cross sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangular Ag particles and related shapes.
- 21Suzuki, M.; Niidome, Y.; Kuwahara, Y.; Terasaki, N.; Inoue, K.; Yamada, S. Surface-enhanced nonresonance Raman scattering from size-and morphology-controlled gold nanoparticle films. J. Phys. Chem. B 2004, 108, 11660– 11665, DOI: 10.1021/jp0490150Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXlsVyrsbc%253D&md5=b6c93d340fc5ebac240754d9152c1ed3Surface-Enhanced Nonresonance Raman Scattering from Size- and Morphology-Controlled Gold Nanoparticle FilmsSuzuki, Mototsugu; Niidome, Yasuro; Kuwahara, Yutaka; Terasaki, Nao; Inoue, Kazuma; Yamada, SunaoJournal of Physical Chemistry B (2004), 108 (31), 11660-11665CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)Gold nanoparticle films with different particles sizes (35 ± 5, 15 ± 1 nm) and agglomerated states were prepd. on glass substrates, by salting-out the colloidal solns. with NaClO4 or NaOH. An ethanol soln. of rhodamine 6G was cast on the gold nanoparticle film and the surface-enhanced Raman scattering (SERS) spectrum was measured. We found that the intensity of the SERS signal was higher for the film with larger particles and that the film prepd. from NaClO4 gave higher SERS signals than that prepd. from NaOH. Considerable coalescence of larger gold nanoparticles was quite effective for obtaining larger SERS signals. The SERS enhancement factor was estd. to be ∼108 for the film prepd. from NaClO4.
- 22Bell, S. E. J.; McCourt, M. R. SERS enhancement by aggregated Au colloids: effect of particle size. Phys. Chem. Chem. Phys. 2009, 11, 7455– 7462, DOI: 10.1039/b906049aGoogle Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVSmtrjP&md5=49fa0b160100872d5b002db7d5c4e667SERS enhancement by aggregated Au colloids: effect of particle sizeBell, Steven E. J.; McCourt, Maighread R.Physical Chemistry Chemical Physics (2009), 11 (34), 7455-7462CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Aggregated Au colloids were widely used as SERS enhancing media for many years but to date there was no systematic study of the effect of the particle size on the enhancements given by simple aggregated Au colloid solns. Previous systematic studies on isolated particles in soln. or multiple particles deposited onto surfaces reported widely different optimum particle sizes for the same excitation wavelength and also disagreed on the extent to which surface plasmon absorption spectra were a good predictor of enhancement factors. The spectroscopic properties of a range of samples of monodisperse Au colloids with diams. ranging from 21 to 146 nm were studied in soln. The UV/visible absorption spectra of the colloids show complex changes as a function of aggregating salt (MgSO4) concn. which diminish when the colloid is fully aggregated. Under these conditions, the relative SERS enhancements provided by the variously sized colloids vary very significantly across the size range. The largest signals in the raw data are obsd. for 46 nm colloids but correction for the total surface area available to generate enhancement shows that particles with 74 nm diam. give the largest enhancement per unit surface area. The obsd. enhancements do not correlate with absorbance at the excitation wavelength but the large differences between differently sized colloids demonstrate that even in the randomly aggregated particle assemblies studied here, inhomogeneous broadening does not mask the underlying changes due to differences in particle diam.
- 23Yang, Y.; Zhang, Q.; Fu, Z.; Qin, D. Transformation of Ag Nanocubes into Ag-Au Hollow Nanostructures with Enriched Ag Contents to Improve SERS Activity and Chemical Stability. ACS Appl. Mater. Interfaces 2014, 6, 3750– 3757, DOI: 10.1021/am500506jGoogle Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhsVKls78%253D&md5=ea8ee017cbbe12546af00378816c0af7Transformation of Ag Nanocubes into Ag-Au Hollow Nanostructures with Enriched Ag Contents to Improve SERS Activity and Chemical StabilityYang, Yin; Zhang, Qiang; Fu, Zheng-Wen; Qin, DongACS Applied Materials & Interfaces (2014), 6 (5), 3750-3757CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)The authors report a strategy to complement the galvanic replacement reaction between Ag nanocubes and HAuCl4 with co-redn. by ascorbic acid (AA) for the formation of Ag-Au hollow nanostructures with greatly enhanced SERS activity. In the early stage of synthesis, the Ag nanocubes are sharpened at corners and edges because of the selective deposition of Au and Ag atoms at these sites. In the following steps, the pure Ag in the nanocubes is constantly converted into Ag+ ions to generate voids owing to the galvanic reaction with HAuCl4, but these released Ag+ ions are immediately reduced back to Ag atoms and are co-deposited with Au atoms onto the nanocube templates. Distinctive SERS properties were obsd. for the Ag-Au hollow nanostructures at visible and near-IR excitation wavelengths. When plasmon damping was eliminated by using an excitation wavelength of 785 nm, the SERS activity of the Ag-Au hollow nanostructures was 15- and 33-fold stronger than those of the original Ag nanocubes and the Ag-Au nanocages prepd. by galvanic replacement without co-redn., resp. The Ag-Au hollow nanostructures embrace considerably improved stability in an oxidizing environment such as aq. H2O2 soln.
- 24Yang, Y.; Liu, J.; Fu, Z.; Qin, D. Galvanic Replacement-Free Deposition of Au on Ag for Core-Shell Nanocubes with Enhanced Chemical Stability and SERS Activity. J. Am. Chem. Soc. 2014, 136, 8153– 8156, DOI: 10.1021/ja502472xGoogle Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXos1WmtLY%253D&md5=fd0fa35c9bad1429840b184b24bd2983Galvanic Replacement-Free Deposition of Au on Ag for Core-Shell Nanocubes with Enhanced Chemical Stability and SERS ActivityYang, Yin; Liu, Jingyue; Fu, Zheng-Wen; Qin, DongJournal of the American Chemical Society (2014), 136 (23), 8153-8156CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The authors report a robust synthesis of Ag@Au core-shell nanocubes by directly depositing Au atoms on the surfaces of Ag nanocubes as conformal, ultrathin shells. The success relies on the introduction of a strong reducing agent to compete with and thereby block the galvanic replacement between Ag and HAuCl4. An ultrathin Au shell of 0.6 nm thick was able to protect the Ag in the core in an oxidative environment. Significantly, the core-shell nanocubes exhibited surface plasmonic properties essentially identical to those of the original Ag nanocubes, while the SERS activity showed a 5.4-fold further enhancement owing to an improvement in chem. enhancement. The combination of excellent SERS activity and chem. stability may enable a variety of new applications.
- 25Mai, F.-D.; Yang, K.-H.; Liu, Y.-C.; Hsu, T.-C. Improved Stabilities on Surface-Enhanced Raman Scattering-Active Ag/Al2O3 Films on Substrates. Analyst 2012, 137, 5906– 5912, DOI: 10.1039/c2an35829hGoogle ScholarThere is no corresponding record for this reference.
- 26Yang, K.-H.; Liu, Y.-C.; Hsu, T.-C.; Juang, M.-Y. Strategy to Improve Stability of Surface-Enhanced Raman Scattering-Active Ag Substrates. J. Mater. Chem. 2010, 20, 7530– 7535, DOI: 10.1039/c0jm00814aGoogle Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVKhsLnK&md5=9ed7e30eaba44aa5fd21266d2a1f0d8dStrategy to improve stability of surface-enhanced Raman scattering-active Ag substratesYang, Kuang-Hsuan; Liu, Yu-Chuan; Hsu, Ting-Chu; Juang, Ming-YuJournal of Materials Chemistry (2010), 20 (35), 7530-7535CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)Surface-enhanced Raman scattering (SERS)-active Ag substrates were popularly employed for evaluating the structural situation of analytes because SERS-active Ag substrates can demonstrate more significant SERS effects than Au and Cu substrates. However, the stability of SERS-active Ag substrates is an issue of concern in their application. In this work, SERS-active modified Ag substrates were simply prepd. in 0.1 N HCl solns. contg. Al2O3 nanoparticles by electrochem. methods. Exptl. results indicate that the Al2O3-modified Ag substrate can significantly improve its thermal stability by raising the operation temp. of the Ag substrate by over 100 °C. Moreover, the aging of SERS enhancement capabilities in an atm. of 50% relative humidity (RH) and 20% (vol./vol.) O2 at 30 °C is markedly depressed based on this Al2O3-modified Ag substrate.
- 27Ling, X.; Xie, L.; Fang, Y.; Xu, H.; Zhang, H.; Kong, J.; Dresselhaus, M. S.; Zhang, J.; Liu, Z. Can graphene be used as a substrate for Raman enhancement?. Nano Lett. 2010, 10, 553– 561, DOI: 10.1021/nl903414xGoogle Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhs1altbbF&md5=f70013819a8b2e1ff15687f20b835bc1Can Graphene be used as a Substrate for Raman Enhancement?Ling, Xi; Xie, Liming; Fang, Yuan; Xu, Hua; Zhang, Haoli; Kong, Jing; Dresselhaus, Mildred S.; Zhang, Jin; Liu, ZhongfanNano Letters (2010), 10 (2), 553-561CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Graphene is a monolayer of C atoms packed into a 2-dimensional (2D) honeycomb crystal structure, which is a special material with many excellent properties. The possibility that graphene can be used as a substrate for enhancing Raman signals of adsorbed mols. is discussed. Phthalocyanine (Pc), Rhodamine 6G (R6G), protoporphyin IX (PPP), and crystal violet (CV), which are popular mols. widely used as a Raman probe, are deposited equally on graphene and a SiO2/Si substrate using vacuum evapn. or soln. soaking. By comparing the Raman signals of mols. on monolayer graphene and on a SiO2/Si substrate, the intensities of the Raman signals on monolayer graphene are much stronger than on a SiO2/Si substrate, indicating a clear Raman enhancement effect on the surface of monolayer graphene. For soln. soaking, the Raman signals of the mols. are visible even though the concn. is low to ≤10-8 mol/L. The enhanced efficiencies are quite different on monolayer, few-layer, multilayer graphene, graphite, and highly ordered pyrolytic graphite (HOPG). The Raman signals of mols. on multilayer graphene are even weaker than on a SiO2/Si substrate, and the signals are even invisible on graphite and HOPG. Taking the Raman signals on the SiO2/Si substrate as a ref., Raman enhancement factors on the surface of monolayer graphene can be obtained using Raman intensity ratios. The Raman enhancement factors are quite different for different peaks, changing from 2 to 17. The Raman enhancement factors can be distinguished through 3 classes that correspond to the symmetry of vibrations of the mol. This enhancement is attributed to the charge transfer between graphene and the mols., which result in a chem. enhancement. This is a new phenomenon for graphene that will expand the application of graphene to microanal. and is good for studying the basic properties of both graphene and SERS.
- 28Ling, X.; Zhang, J. First-layer effect in graphene-enhanced Raman scattering. Small 2010, 6 (18), 2020– 2025, DOI: 10.1002/smll.201000918Google Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtFynsLnJ&md5=2752a375d4d837700f81ca1a31cf32b0First-layer effect in graphene-enhanced Raman scatteringLing, Xi; Zhang, JinSmall (2010), 6 (18), 2020-2025CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Graphene as a substrate for enhancing Raman scattering, called graphene-enhanced Raman scattering (GERS), was reported in previous work. Herein, the "first-layer effect", which is widely used to explain the chem.-enhanced mechanism in surface-enhanced Raman scattering (SERS), exists in the GERS system. The Langmuir-Blodgett (LB) technique is used to construct mono- and multilayer ordered aggregates of protoporphyrin IX (PPP). Raman spectra of PPP with different layer nos. of the LB film on graphene are collected. The Raman signal from the 1st monolayer LB film of PPP has a larger contribution to the Raman enhancement than that from subsequent monolayers. Meanwhile, the Raman enhancement is dependent on the mol. configuration in contact with graphene, in which the functional group of PPP in direct contact with graphene has a stronger enhancement than other groups. These results reveal that GERS is strongly dependent on the distance between graphene and the mol., which is convincing evidence that the Raman enhancement effect based on graphene belongs to the chem.-enhanced mechanism. This discovery provides a convenient system for the study of the chem.-enhanced mechanism and will benefit further understanding of SERS.
- 29Xu, W.; Mao, N.; Zhang, J. Graphene: A Platform for Surface-Enhanced Raman Spectroscopy. Small 2013, 9 (8), 1206– 1224, DOI: 10.1002/smll.201203097Google Scholar29https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXksFaisLk%253D&md5=584e9ad5bc39cc9d8ce9d70b20e25144Graphene: A Platform for Surface-Enhanced Raman SpectroscopyXu, Weigao; Mao, Nannan; Zhang, JinSmall (2013), 9 (8), 1206-1224CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Surface-enhanced Raman spectroscopy (SERS) imparts Raman spectroscopy with the capability of detecting analytes at the single-mol. level, but the costs are also manifold, such as a loss of signal reproducibility. Despite remarkable steps having been taken, presently SERS still seems too young to shoulder anal. missions in various practical situations. By the virtue of its unique mol. structure and phys./chem. properties, the rise of graphene opens up a unique platform for SERS studies. In this review, the multi-role of graphene played in SERS is overviewed, including as a Raman probe, as a substrate, as an additive, and as a building block for a flat surface for SERS. Apart from versatile improvements of SERS performance towards applications, graphene-involved SERS studies are also expected to shed light on the fundamental mechanism of the SERS effect.
- 30Huh, S.; Park, J.; Kim, Y. S.; Kim, K. S.; Hong, B. H.; Nam, J.-M. UV/Ozone-Oxidized Large-Scale Graphene Platform with Large Chemical Enhancement in Surface-Enhanced Raman Scattering. ACS Nano 2011, 5 (12), 9799– 9806, DOI: 10.1021/nn204156nGoogle Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsVelt7vK&md5=ee9a19b4ec48708ec30050fb59ef7856UV/Ozone-Oxidized Large-Scale Graphene Platform with Large Chemical Enhancement in Surface-Enhanced Raman ScatteringHuh, Sung; Park, Jaesung; Kim, Young Soo; Kim, Kwang S.; Hong, Byung Hee; Nam, Jwa-MinACS Nano (2011), 5 (12), 9799-9806CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)A highly oxidized large-scale graphene platform using CVD and UV/ozone-based oxidn. was fabricated. This platform offers a large-scale SERS substrate with large chem. enhancement in SERS and reproducible SERS signals over a cm-scale graphene surface. After UV-induced O3 generation, O3 mols. were reacted with graphene to produce O-contg. groups on graphene and induced the p-type doping of the graphene. These modifications introduced the structural disorder and defects on the graphene surface and resulted in a large chem. mechanism-based signal enhancement from Raman dye mols. [rhodamine B (RhB), rhodamine 6G (R6G), and crystal violet (CV) in this case] on graphene. Importantly, the enhancement factors were increased from ∼103 before ozone treatment to ∼104, which is the largest chem. enhancement factor ever on graphene, after 5 min ozone treatment due to both high oxidn. and p-doping effects on graphene surface. Over a centimeter-scale area of this UV/ozone-oxidized graphene substrate, strong SERS signals were repeatedly and reproducibly detected. In a UV/ozone-based micropattern, UV/ozone-treated areas were highly Raman-active while nontreated areas displayed very weak Raman signals.
- 31Chugh, D.; Jagadish, C.; Tan, H. Large-area hexagonal boron nitride for surface enhanced Raman spectroscopy. Adv. Mater. Technol. 2019, 4, 1900220, DOI: 10.1002/admt.201900220Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXisVart73E&md5=a53ceed6afd5678e65db5fd74c0967b4Large-Area Hexagonal Boron Nitride for Surface Enhanced Raman SpectroscopyChugh, Dipankar; Jagadish, Chennupati; Tan, HoeAdvanced Materials Technologies (Weinheim, Germany) (2019), 4 (8), 1900220CODEN: AMTDCM; ISSN:2365-709X. (Wiley-VCH Verlag GmbH & Co. KGaA)Application of atomically thin layers of hexagonal boron nitride (hBN) for passivating gold and silver nanoparticles is investigated and its potential use is demonstrated through surface-enhanced Raman spectroscopy (SERS). Silver nanoparticles readily oxidize in air, resulting in a significant decrease in its SERS activity. hBN is a novel 2D material, well-known for its thermal and chem. stability. In this study, wafer-scale hBN is grown using metal org. vapor phase epitaxy (MOVPE) and centimeter-sized hBN layers are transferred on to silver nanoparticles. hBN acts as an impermeable barrier and protects silver nanoparticles from oxidn., even at elevated temps. and help retain its SERS activity. Thermal stability of hBN coated Ag nanoparticles is studied in detail. Furthermore, wafer-scale hBN layers grown using MOVPE are esp. attractive, compared to mech. exfoliated, micrometer sized flakes from bulk crystals, as it can be easily scaled-up, shown here through design and fabrication of a SERS chip, conducive for droplet-based anal. Overall, large-area hBN layers are well suited for practical applications and can help improve the shelf-life and reusability of com. available SERS substrates.
- 32Kundu, A.; Rani, R.; Hazra, K. S. Controlled nanofabrication of metal-free SERS substrate on few layered black phosphorus by low power focused laser irradiation. Nanoscale 2019, 11 (35), 16245– 16252, DOI: 10.1039/C9NR02615KGoogle Scholar32https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsFGgtbzJ&md5=bffdf7073124974d1fba76ccd488257dControlled nanofabrication of metal-free SERS substrate on few layered black phosphorus by low power focused laser irradiationKundu, Anirban; Rani, Renu; Hazra, Kiran ShankarNanoscale (2019), 11 (35), 16245-16252CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Black Phosphorous (BP) has intrinsic in-plane ferroelec. properties that may have the inherent capability of SERS response and can be considered as a replacement of metal nanoparticle-based SERS substrates. A simple one-step process has been demonstrated for the controlled nano-structuring and rapid prototyping on a BP flake to develop a metal-free SERS substrate by low power focused laser irradn. The effect of focused laser irradn. on the surface morphol. of the pristine BP flakes has been thoroughly investigated by real time Raman spectroscopy measurements and corresponding AFM height profiling, which confirms that the proposed laser irradn. technique has more advantages over the conventional lithog. and is free from undesired contamination. For a 532 nm laser line, the min. laser power needed to create a nano-void on the BP flake is 25 mW (Power d. = ∼15.62 × 105 W cm-2) with 5 s exposure time, where the etching rate is controlled by the laser power and exposure time. By analyzing the geometrical shape of the nano-void created due to laser irradn., it is possible to identify the armchair and zigzag directions of the BP flake. The exptl. results revealed that by controlling the exposure time and laser power, it was possible to perform layer by layer thinning of BP flakes. The proposed thinning process of the BP flake did not alter the pristine quality and no signature of oxidn. was found in the Raman spectra, which signified the reliability of this low power laser irradn. technique towards the future nano-fabrication of BP-based devices. The controlled formation of the nano-void array on a few layered BP flake enhanced the local elec. field (hot spots) in the vicinity of the nano-voids, resulting in ∼30% Raman intensity enhancement. Such nano-void induced hotspots on the BP flake open up a new species of metal-free SERS substrate, demonstrating pronounced enhancement in the Raman signal of Rhodamine B as high as ∼106 and a limit of detection (LOD) up to ∼10 nM.
- 33Ling, X.; Fang, W.; Lee, Y. H.; Araujo, P. T.; Zhang, X.; Rodriguez-Nieva, J. F.; Lin, Y.; Zhang, J.; Kong, J.; Dresselhaus, M. S. Raman enhancement effect on two-dimensional layered materials: graphene, h-BN and MoS2. Nano Lett. 2014, 14, 3033– 3040, DOI: 10.1021/nl404610cGoogle Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmslGktrg%253D&md5=2ec885dc02666e888d8b51a607b0331aRaman Enhancement Effect on Two-Dimensional Layered Materials: Graphene, h-BN and MoS2Ling, Xi; Fang, Wenjing; Lee, Yi-Hsien; Araujo, Paulo T.; Zhang, Xu; Rodriguez-Nieva, Joaquin F.; Lin, Yuxuan; Zhang, Jin; Kong, Jing; Dresselhaus, Mildred S.Nano Letters (2014), 14 (6), 3033-3040CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Realizing Raman enhancement on a flat surface has become increasingly attractive after the discovery of graphene-enhanced Raman scattering (GERS). Two-dimensional (2D) layered materials, exhibiting a flat surface without dangling bonds, were thought to be strong candidates for both fundamental studies of this Raman enhancement effect and its extension to meet practical applications requirements. Here, we study the Raman enhancement effect on graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS2), by using the copper phthalocyanine (CuPc) mol. as a probe. This mol. can sit on these layered materials in a face-on configuration. However, it is found that the Raman enhancement effect, which is observable on graphene, hBN, and MoS2, has different enhancement factors for the different vibrational modes of CuPc, depending strongly on the surfaces. Higher-frequency phonon modes of CuPc (such as those at 1342, 1452, 1531 cm-1) are enhanced more strongly on graphene than that on h-BN, while the lower frequency phonon modes of CuPc (such as those at 682, 749, 1142, 1185 cm-1) are enhanced more strongly on h-BN than that on graphene. MoS2 demonstrated the weakest Raman enhancement effect as a substrate among these three 2D materials. These differences are attributed to the different enhancement mechanisms related to the different electronic properties and chem. bonds exhibited by the three substrates: (1) graphene is zero-gap semiconductor and has a nonpolar C-C bond, which induces charge transfer (2) h-BN is insulating and has a strong B-N bond, while (3) MoS2 is semiconducting with the sulfur atoms on the surface and has a polar covalent bond (Mo-S) with the polarity in the vertical direction to the surface. Therefore, the different Raman enhancement mechanisms differ for each material: (1) charge transfer may occur for graphene; (2) strong dipole-dipole coupling may occur for h-BN, and (3) both charge transfer and dipole-dipole coupling may occur, although weaker in magnitude, for MoS2. Consequently, this work studied the origin of the Raman enhancement (specifically, chem. enhancement) and identifies h-BN and MoS2 as two different types of 2D materials with potential for use as Raman enhancement substrates.
- 34Xu, Y. Y.; Yang, C.; Jiang, S. Z.; Man, B. Y.; Liu, M.; Chen, C. S.; Zhang, C.; Sun, Z. C.; Qiu, H. W.; Li, H. S.; Feng, D. J.; Zhang, J. X. Layer-controlled large area MoS2 layers grown on mica substrate for surface-enhanced Raman scattering. Appl. Surf. Sci. 2015, 357, 1708– 1713, DOI: 10.1016/j.apsusc.2015.10.032Google ScholarThere is no corresponding record for this reference.
- 35Lv, Q.; Tan, J.; Wang, Z.; Yu, L.; Liu, B.; Lin, J.; Li, J.; Huang, Z.-H.; Kang, F.; Lv, R. Femtomolar-Level Molecular Sensing of Monolayer Tungsten Diselenide Induced by Heteroatom Doping with Long-Term Stability. Adv. Funct. Mater. 2022, 32 (34), 2200273, DOI: 10.1002/adfm.202200273Google ScholarThere is no corresponding record for this reference.
- 36Yin, Y.; Miao, P.; Zhang, Y.; Han, J.; Zhang, X.; Gong, Y.; Gu, L.; Xu, C.; Yao, T.; Xu, P. Significantly increased Raman enhancement on MoX2 (X = S, Se) monolayers upon phase transition. Adv. Funct. Mater. 2017, 27, 1606694, DOI: 10.1002/adfm.201606694Google ScholarThere is no corresponding record for this reference.
- 37Yan, D.; Qiu, W.; Chen, X.; Liu, L.; Lai, Y.; Meng, Z.; Song, J.; Liu, Y.; Liu, X.-Y.; Zhan, D. Achieving High-Performance Surface-Enhanced Raman Scattering through One-Step Thermal Treatment of Bulk MoS2. J. Phys. Chem. C 2018, 122, 14467– 14473, DOI: 10.1021/acs.jpcc.8b01822Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtVKgtLnN&md5=5c6f5eb43197803252c1baef5f7e7bfeAchieving High-Performance Surface-Enhanced Raman Scattering through One-Step Thermal Treatment of Bulk MoS2Yan, Dandan; Qiu, Wu; Chen, Xuejiao; Liu, Lei; Lai, Yongjue; Meng, Zhaohui; Song, Jiepeng; Liu, Yufei; Liu, Xiang-Yang; Zhan, DaJournal of Physical Chemistry C (2018), 122 (26), 14467-14473CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)We present a strong Raman enhancement substrate through one-step thermal treatment of bulk MoS2. The substrate provides very efficient hot spots by using the rhodamine 6G (R6G) mol. as a probe. Raman and photoluminescence spectra of modified MoS2 reveal the detailed mechanism for enhancing Raman signal of R6G. It is found that both the substrate roughness and the slight chem. bond broken on the surface are the main driven forces to induce the surface enhanced Raman scattering (SERS) effects. The min. detectable concn. of R6G on the most optimized thermally treated MoS2 can be as low as 10-8 M. This synthetic approach is facile, sensitive, and reliable, which shows great potential to be an excellent SERS substrate for biol. and chem. detection.
- 38Wang, Y.; Ni, Z.; Hu, H.; Hao, Y.; Wong, C. P.; Yu, T.; Thong, J. T.; Shen, Z. X. Gold on Graphene as a Substrate for Surface Enhanced Raman Scattering Study. Appl. Phys. Lett. 2010, 97, 163111, DOI: 10.1063/1.3505335Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtlWhsLvF&md5=0a3d5e33bd42ef138f55839c4e54c633Gold on graphene as a substrate for surface enhanced Raman scattering studyWang, Yingying; Ni, Zhenhua; Hu, Hailong; Hao, Yufeng; Wong, Choun Pei; Yu, Ting; Thong, John T. L.; Shen, Ze XiangApplied Physics Letters (2010), 97 (16), 163111/1-163111/3CODEN: APPLAB; ISSN:0003-6951. (American Institute of Physics)The authors report the authors' study on Au films with different thicknesses deposited on single layer graphene (SLG) as surface enhanced Raman scattering (SERS) substrates for the characterization of rhodamine (R6G) mols. An Au film with a thickness of ∼7 nm deposited on SLG is an ideal substrate for SERS, giving the strongest Raman signals for the mols. and the weakest photoluminescence (PL) background. While Au films effectively enhance both the Raman and PL signals of mols., SLG effectively quenches the PL signals from the Au film and mols. The former is due to the electromagnetic mechanism involved while the latter is due to the strong resonance energy transfer from Au to SLG. Hence, the combination of Au films and SLG can be widely used in the characterization of low concn. mols. with relatively weak Raman signals. (c) 2010 American Institute of Physics.
- 39Zhou, H.; Qiu, C.; Yu, F.; Yang, H.; Chen, M.; Hu, L.; Sun, L. Thickness-Dependent Morphologies and Surface-Enhanced Raman Scattering of Ag Deposited on n-Layer Graphenes. J. Phys. Chem. C 2011, 115, 11348– 11354, DOI: 10.1021/jp112421qGoogle Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXmtlylsL0%253D&md5=2d6b712da0fff4dcde5edad9b2d06733Thickness-Dependent Morphologies and Surface-Enhanced Raman Scattering of Ag Deposited on n-Layer GraphenesZhou, Haiqing; Qiu, Caiyu; Yu, Fang; Yang, Huaichao; Chen, Minjiang; Hu, Lijun; Sun, LianfengJournal of Physical Chemistry C (2011), 115 (23), 11348-11354CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)After thermal deposition of silver films onto n-layer graphenes, the following results have been obtained. First, the dependence of silver morphologies on the layer no. is studied via controlling the sample temp. at 298, 333, and 373 K. This can be attributed to the changes in surface properties and/or surface diffusion coeff. of n-layer graphenes at different temps. Second, Raman scattering of n-layer graphenes is greatly enhanced after Ag deposition and the enhancement factors depend on the layer no. of n-layer graphenes. Monolayer graphene has the largest enhancement factors, and the enhancement factors decrease with layer no. increasing. For graphite, almost no enhancement effect has been detected. Third, the dependences of the enhancement factors on laser wavelength, thickness, and morphologies (nanoparticle size and spacing) of silver film are also studied. The Raman enhancement obsd. here is mainly attributed to the coupled surface plasmon resonance (SPR) absorption of silver nanoparticles.
- 40Sidorov, A. N.; Sławiński, G. W.; Jayatissa, A. H.; Zamborini, F. P.; Sumanasekera, G. U. A surface-enhanced Raman spectroscopy study of thin graphene sheets functionalized with gold and silver nanostructures by seed-mediated growth. Carbon 2012, 50 (2), 699– 705, DOI: 10.1016/j.carbon.2011.09.030Google Scholar40https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtlyrsrvI&md5=07155ec3f2bbf58bd8e7014dc7c1a230A surface-enhanced Raman spectroscopy study of thin graphene sheets functionalized with gold and silver nanostructures by seed-mediated growthSidorov, Anton N.; Slawinski, Grzegorz W.; Jayatissa, A. H.; Zamborini, Francis P.; Sumanasekera, Gamini U.Carbon (2012), 50 (2), 699-705CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)We describe a simple method for decorating graphene (1-5 layers) with Au and Ag nanostructures (nanoparticles, nanorods, and nanoplates). We deposit graphene electrostatically from highly-oriented pyrolytic graphite onto Si/SiO2 surfaces functionalized with (aminopropyl)trimethoxysilane and grow the metal nanostructures by a seed-mediated growth method from hexanethiolate-coated Au monolayer-protected cluster "seeds" that are attached to graphene by hydrophobic interactions. SEM reveals the selective growth of Au or Ag nanostructures on the graphene surface. In the case of Au, the low pH 2.8 growth soln. causes etching of the graphene and formation of scroll-like structures. For Ag, the high pH 9.3 soln. does not seem to affect the graphene. Raman spectroscopy is consistent with the graphene morphol. and reveals that the presence of Au and Ag nanostructures increases the Raman scattering from the graphene by a factor of about 45 and 150, resp. This work demonstrates a simple method for decorating graphene with noble metal nanostructures that may have interesting optical, electronic, and chem. properties for applications in nanoelectronics, sensing, and catalysis.
- 41Wang, X.; Wang, N.; Gong, T.; Zhu, Y.; Zhang, J. Preparation of Graphene-Ag Nanoparticles Hybrids and Their SERS Activities. Appl. Surf. Sci. 2016, 387, 707– 719, DOI: 10.1016/j.apsusc.2016.06.161Google Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtVynurzN&md5=ef8331b37f1e87aa8bf11acdb1f8d088Preparation of graphene-Ag nanoparticles hybrids and their SERS activitiesWang, Xinyu; Wang, Ning; Gong, Tiancheng; Zhu, Yong; Zhang, JieApplied Surface Science (2016), 387 (), 707-719CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Surface-enhanced Raman scattering (SERS) substrates based on graphene and Ag nanoparticles hybrid structures with low cost, high uniformity were prepd. by a std. process of immobilization of silver nanoparticles with 3-aminopropyltrimethoxysilane (APTMS). Thermal annealing was used for removing residual APTMS and adjusting the morphol. of silver nanoparticles, and the effectiveness of this method was verified exptl. The influence of annealing temp., dipping duration, and APTMS vol. on the distribution of Ag nanoparticles and Raman enhancement was investigated exptl. and analyzed in detail. Our samples were prepd. under the prepn. conditions of 10% ν/ν APTMS, dipping time of 48 h, annealing temp. of 450 °C, duration of 30 min, and Ar flow rate of 40 sccm. SERS activities with enhancement of 107 and relative std. deviation of <20% were obsd. using rhodamine 6G (R6G) as probe mol. with a concn. of 10-6 M and 10-7 M.
- 42Xu, S.; Jiang, S.; Wang, J.; Wei, J.; Yue, W.; Ma, Y. Graphene Isolated Au Nanoparticle Arrays with High Reproducibility for High-Performance Surface-Enhanced Raman Scattering. Sens. Actuators, B 2016, 222, 1175– 1183, DOI: 10.1016/j.snb.2015.08.009Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtlylsb3F&md5=61037e9466a2a5933434f616411be43dGraphene isolated Au nanoparticle arrays with high reproducibility for high-performance surface-enhanced Raman scatteringXu, Shicai; Jiang, Shouzhen; Wang, Jihua; Wei, Jie; Yue, Weiwei; Ma, YongSensors and Actuators, B: Chemical (2016), 222 (), 1175-1183CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)An efficient surface enhanced Raman scattering (SERS) substrate has been developed based on highly ordered arrays of graphene-isolated Au nanoparticle (G/AuNP). By combining the electromagnetic enhancement activity of AuNP arrays and unique phys./chem. properties of graphene, the G/AuNP arrays shows high performance in terms of sensitivity, signal-to-noise ratio and reproducibility. The av. enhancement factor obtained from the G/AuNP arrays for rhodamine 6G probe mols. is over 107. The max. deviations of SERS intensities from 20 positions of a same SERS substrate are in the range of 4.74% to 6.89% and from 20 different substrates in various batches are in the range of 5.67% to 8.37%, depending on different vibration modes. As a practical application of this SERS system, we detect the adenosine concn. in human serum. The detection results show a good linear correlation between SERS intensity and adenosine concn. within the range of 2 to 250 nM. This work may open up new opportunities in developing the applications of SERS in biomedical diagnostics, biol. sensing and other biotechnol.
- 43Jiang, J.; Zou, J.; Wee, A. T. S.; Zhang, W. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS). Sci. Rep. 2016, 6, 34599, DOI: 10.1038/srep34599Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xhs1SrsrnN&md5=b21382dea1cdda2eb080dc0624ce1fa9Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, WenjingScientific Reports (2016), 6 (), 34599CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single at. layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of expts. and theor. calcns. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidn. Based on the theor. calcns., we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was pos. and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.
- 44Wang, J.; Liu, R.; Zhang, C.; Han, G.; Zhao, J.; Liu, B.; Jiang, C.; Zhang, Z. Synthesis of g-C3N4 nanosheet/Au@Ag nanoparticle hybrids as SERS probes for cancer cell diagnostics. RSC Adv. 2015, 5, 86803– 86810, DOI: 10.1039/C5RA16558JGoogle ScholarThere is no corresponding record for this reference.
- 45Zhang, H.; Li, G.; Li, S.; Xu, L.; Tian, Y.; Jiao, A.; Liu, X.; Chen, F.; Chen, M. Boron nitride/gold nanocomposites for crystal violet and creatinine detection by surface-enhanced Raman spectroscopy. Appl. Surf. Sci. 2018, 457, 684– 694, DOI: 10.1016/j.apsusc.2018.06.295Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXht12jtL7I&md5=492706ff98ef3776c16c6c2fd92863c1Boron nitride/gold nanocomposites for crystal violet and creatinine detection by surface-enhanced Raman spectroscopyZhang, Hua; Li, Guanhua; Li, Shuang; Xu, Linlin; Tian, Yue; Jiao, Anxin; Liu, Xiangdong; Chen, Feng; Chen, MingApplied Surface Science (2018), 457 (), 684-694CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Hexagonal boron nitride/gold nanocomposites (h-BN/Au NCs) were fabricated and developed for ultra-sensitive detection of crystal violet (CV) and creatinine mols. using surface enhanced Raman scattering spectroscopy (SERS). The overgrowth of Au nanoparticles was driven by laser-induced photoexcitation of h-BN, which was monitored by absorption spectra. The h-BN/Au NCs with controllable Au compns. (0-1.85%) were characterized using Transmission Electron Microscopy (TEM), Scan Electron Microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). The microstructural analyses indicated that mono-dispersed Au nanoparticles with size of ∼10 nm can be accreted on h-BN via 30 min synthetic reaction. The comparative SERS results reveal that the h-BN/Au NCs with 1.68% Au compn. provide enhanced SERS activity in comparison with other nanosubstrates in this paper. The corresponding enhancement mechanism of h-BN/Au NCs has been illustrated in detail, which can be composed of four contributions in our research. Then, the SERS analyses demonstrated that the detection limit of CV mols. was achieved at femtomole level of ∼10-15 M, leading to ultrasensitive monitoring of dye pollution. More importantly, well-defined linear relationships were established between SERS signal intensities and logarithmical scale of creatinine concn. (10-2-10-6 M), providing a precise assessment of creatinine in pathol. diagnostics.
- 46Lin, Y.; Bunker, C. E.; Fernando, K. A. S.; Connell, J. W. Aqueously Dispersed Silver Nanoparticle-Decorated Boron Nitride Nanosheets for Reusable, Thermal Oxidation-Resistant Surface Enhanced Raman Spectroscopy (SERS) Devices. ACS Appl. Mater. Interfaces 2012, 4 (2), 1110– 1117, DOI: 10.1021/am201747dGoogle ScholarThere is no corresponding record for this reference.
- 47Yang, S.; Zhang, Z.; Zhao, J.; Zheng, H. High surface enhanced Raman scattering activity of BN nanosheets–Ag nanoparticles hybrids. J. Alloys Compd. 2014, 583, 231– 236, DOI: 10.1016/j.jallcom.2013.08.178Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhs1OjurzJ&md5=bb14ef72fea3a703074b8edd965b6bbbHigh surface enhanced Raman scattering activity of BN nanosheets-Ag nanoparticles hybridsYang, Shanshan; Zhang, Zhaochun; Zhao, Jun; Zheng, HouliJournal of Alloys and Compounds (2014), 583 (), 231-236CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)A facile liq.-phase reducing route was developed to modify boron nitride (BN) nanosheets with silver nanoparticles (AgNPs) in order to fabricate BN-AgNPs hybrids with high surface enhanced Raman scattering (SERS) activity. The layered structure and morphol. of BN-AgNPs nanohybrids were characterized by transmission electron microscopy and at. force microscopy, meanwhile, Fourier transform IR spectroscopy and UV-visible were used for studying optical properties and surface plasmon resonance applied to the optical sensor. The SERS of adsorbed 2-mercaptobenzimidazole (MBI) mol. was investigated which shown that the BN-AgNPs substrate exhibited a very strong SERS activity, offering a great potential application in mol. probe sensor. On the basis of the anal. of SERS and the Raman surface selection rules, it was concluded that the MBI mol. was adsorbed upright on the AgNPs surface through the sulfur and nitrogen atoms. Cyclic voltammetry indicated the electrochem. irreversible behavior of BN-AgNPs nanohybrids in KCl soln.
- 48Yang, G.; Liu, Z.; Li, Y.; Hou, Y.; Fei, X.; Su, C.; Wang, S.; Zhuang, Z.; Guo, Z. Facile synthesis of black phosphorus–Au nanocomposites for enhanced photothermal cancer therapy and surface-enhanced Raman scattering analysis. Biomater. Sci. 2017, 5, 2048– 2055, DOI: 10.1039/C7BM00414AGoogle Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVyhtbzM&md5=2fb69cc57573b07759d0ef2966b9e010Facile synthesis of black phosphorus-Au nanocomposites for enhanced photothermal cancer therapy and surface-enhanced Raman scattering analysisYang, Guangcun; Liu, Zhiming; Li, Yi; Hou, Yuqing; Fei, Xixi; Su, Chengkang; Wang, Songmao; Zhuang, Zhengfei; Guo, ZhouyiBiomaterials Science (2017), 5 (10), 2048-2055CODEN: BSICCH; ISSN:2047-4849. (Royal Society of Chemistry)Black phosphorus (BP), a new type of two-dimensional nanomaterial, has attracted crucial attention in recent years owing to its excellent properties and great potential in various chem., phys., and biol. fields. In this study, BP nanosheets loaded with Au nanoparticles (BP-Au NSs) are obtained by a one-step facile synthetic method. The Au nanostructures can not only enhance the photothermal efficiency of the nanocomposites, but also endow BP-Au NSs with the potential to act as effective surface-enhanced Raman scattering (SERS) substrates for Raman biodetection. Cancer photothermal therapy (PTT) has been carried out in vitro and in vivo using BP-Au NSs as nanoagents. Under irradn. by an 808 nm laser, BP-Au NSs are capable of producing sufficient hyperthermia to destroy cancer cells, and the transplanted tumors in most of the tumor-bearing mice disappeared; BP-Au NSs are more effective than bare BP nanosheets. The PTT effect can also be monitored by a Raman technique that benefits from the high SERS activity of the BP-Au NSs. The mol. fingerprint features of breast tumors before and after PTT treatment were clearly identified using SERS anal. The theranostic applications of BP-Au NSs exhibit promising potential in biomedicine.
- 49Lin, C.; Liang, S.; Peng, Y.; Long, L.; Li, Y.; Huang, Z.; Long, N. V.; Luo, X.; Liu, J.; Li, Z.; Yang, Y. Visualized SERS Imaging of Single Molecule by Ag/Black Phosphorus Nanosheets. Nano-Micro Lett. 2022, 14, 75, DOI: 10.1007/s40820-022-00803-xGoogle Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XpvVyhsrc%253D&md5=f815fdb45bc6a098348434fae6516ce8Visualized SERS imaging of single molecule by Ag/black phosphorus nanosheetsLin, Chenglong; Liang, Shunshun; Peng, Yusi; Long, Li; Li, Yanyan; Huang, Zhengren; Long, Nguyen Viet; Luo, Xiaoying; Liu, Jianjun; Li, Zhiyuan; Yang, YongNano-Micro Letters (2022), 14 (), 75CODEN: NLAEBV; ISSN:2150-5551. (Nano-Micro Letters)Single-mol. detection and imaging are of great value in chem. anal., biomarker identification and other trace detection fields. However, the localization and visualization of single mol. are still quite a challenge. Here, we report a special-engineered nanostructure of Ag nanoparticles embedded in multi-layer black phosphorus nanosheets (Ag/BP-NS) synthesized by a unique photoredn. method as a surface-enhanced Raman scattering (SERS) sensor. Such a SERS substrate features the lowest detection limit of 10-20 mol L-1 for R6G, which is due to the three synergistic resonance enhancement of mol. resonance, photo-induced charge transfer resonance and electromagnetic resonance. We propose a polarization-mapping strategy to realize the detection and visualization of single mol. In addn., combined with machine learning, Ag/BP-NS substrates are capable of recognition of different tumor exosomes, which is meaningful for monitoring and early warning of the cancer. This work provides a reliable strategy for the detection of single mol. and a potential candidate for the practical bio-application of SERS technol.
- 50Kim, J.; Byun, S.; Smith, A. J.; Yu, J.; Huang, J. Enhanced Electrocatalytic Properties of Transition-Metal Dichalcogenides Sheets by Spontaneous Gold Nanoparticle Decoration. J. Phys. Chem. Lett. 2013, 4 (8), 1227– 1232, DOI: 10.1021/jz400507tGoogle Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXks1Gjsrk%253D&md5=7958d31f758a3fbbd7897f31f9dce6b4Enhanced Electrocatalytic Properties of Transition-Metal Dichalcogenides Sheets by Spontaneous Gold Nanoparticle DecorationKim, Jaemyung; Byun, Segi; Smith, Alexander J.; Yu, Jin; Huang, JiaxingJournal of Physical Chemistry Letters (2013), 4 (8), 1227-1232CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)Here, the authors report that transition-metal dichalcogenides such as MoS2 and WS2 can be decorated with Au nanoparticles by a spontaneous redox reaction with tetrachloroauric acid in H2O. The resulting Au nanoparticles tend to grow at defective sites, and therefore, selective decorations at the edges and the line defects in the basal planes of bulk single crystals were obsd. The Li intercalation-exfoliation process makes the basal planes of chem. exfoliated MoS2 and WS2 sheets much more defective than their single-cryst. counterparts, leading to a more uniform and higher-d. deposition of Au nanoparticles. Due to the greatly improved charge transport between adjacent sheets, the resulting MoS2/Au and WS2/Au hybrids show significantly enhanced electrocatalytic performance toward H evolution reactions.
- 51Li, J.; Zhang, W.; Lei, H.; Li, B. Ag nanowire/nanoparticle-decorated MoS2 monolayers for surface-enhanced Raman scattering applications. Nano Res. 2018, 11 (4), 2181– 2189, DOI: 10.1007/s12274-017-1836-4Google Scholar51https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhsFOlsb3K&md5=471b37970602d5f7a13df23e5ea4ba24Ag nanowire/nanoparticle-decorated MoS2 monolayers for surface-enhanced Raman scattering applicationsLi, Juan; Zhang, Weina; Lei, Hongxiang; Li, BaojunNano Research (2018), 11 (4), 2181-2189CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)Developing well-defined nanostructures with superior surface-enhanced Raman scattering (SERS) performance is a crit. and highly desirable goal for the practical applications of SERS in sensing and anal. Here, a SERS-active substrate was fabricated by decorating a MoS2 monolayer with Ag nanowire (NW) and nanoparticle (NP) structures, using a spin-coating method. Both exptl. and theor. results indicate that strong SERS signals of rhodamine 6G (R6G) mols. can be achieved at "hotspots" formed in the Ag NW-Ag NP-MoS2 hybrid structure, with an enhancement factor of 106. The SERS enhancement is found to be strongly polarization dependent. The fabricated SERS substrate also exhibits ultrasensitive detection capabilities with a detection limit of 10-11 M, as well as reliable reproducibility and good stability. [Figure not available: see fulltext.].
- 52Pramanik, A.; Davis, D.; Patibandla, S.; Begum, S.; Ray, P.; Gates, K.; Gao, Y.; Chandra Ray, P. A WS2-gold nanoparticle heterostructure-based novel SERS platform for the rapid identification of antibiotic-resistant pathogens. Nanoscale Adv. 2020, 2, 2025– 2033, DOI: 10.1039/d0na00141dGoogle ScholarThere is no corresponding record for this reference.
- 53Majumdar, D.; Jana, S.; Ray, S. K. Gold nanoparticles decorated 2D-WSe2 as a SERS substrate. Spectrochim. Acta, Part A 2022, 278, 121349, DOI: 10.1016/j.saa.2022.121349Google ScholarThere is no corresponding record for this reference.
- 54Pyrak, E.; Krajczewski, J.; Kowalik, A.; Kudelski, A.; Jaworska, A. Surface enhanced Raman spectroscopy for DNA biosensors─how far are we?. Molecules 2019, 24 (24), 4423, DOI: 10.3390/molecules24244423Google ScholarThere is no corresponding record for this reference.
- 55Liu, T.; Tsai, K. T.; Wang, H. H.; Chen, Y.; Chen, Y. H.; Chao, Y. C.; Chang, H. H.; Lin, C. H.; Wang, J. K.; Wang, Y. L. Functionalized Arrays of Raman-Enhancing Nanoparticles for Capture and Culture-Free Analysis of Bacteria in Human Blood. Nat. Commun. 2011, 2, 538, DOI: 10.1038/ncomms1546Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC38%252FgsVSisw%253D%253D&md5=733174ed9f40e470027755e585d5664aFunctionalized arrays of Raman-enhancing nanoparticles for capture and culture-free analysis of bacteria in human bloodLiu Ting-Yu; Tsai Kun-Tong; Wang Huai-Hsien; Chen Yu; Chen Yu-Hsuan; Chao Yuan-Chun; Chang Hsuan-Hao; Lin Chi-Hung; Wang Juen-Kai; Wang Yuh-LinNature communications (2011), 2 (), 538 ISSN:.Detecting bacteria in clinical samples without using time-consuming culture processes would allow rapid diagnoses. Such a culture-free detection method requires the capture and analysis of bacteria from a body fluid, which are usually of complicated composition. Here we show that coating Ag-nanoparticle arrays with vancomycin (Van) can provide label-free analysis of bacteria via surface-enhanced Raman spectroscopy (SERS), leading to a ~1,000-fold increase in bacteria capture, without introducing significant spectral interference. Bacteria from human blood can be concentrated onto a microscopic Van-coated area while blood cells are excluded. Furthermore, a Van-coated substrate provides distinctly different SERS spectra of Van-susceptible and Van-resistant Enterococcus, indicating its potential use for drug-resistance tests. Our results represent a critical step towards the creation of SERS-based multifunctional biochips for rapid culture- and label-free detection and drug-resistant testing of microorganisms in clinical samples.
- 56Cao, Y. C.; Jin, R. C.; Mirkin, C. A. Nanoparticles with Raman spectroscopic fingerprints for DNA and RNA detection. Science 2002, 297, 1536– 1540, DOI: 10.1126/science.297.5586.1536Google Scholar56https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XmslSjt7c%253D&md5=fd33781690a1ec44ed1cecfdd10bbea2Nanoparticles with Raman spectroscopic fingerprints for DNA and RNA detectionCao, YunWei Charles; Jin, Rongchao; Mirkin, Chad A.Science (Washington, DC, United States) (2002), 297 (5586), 1536-1540CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Multiplexed detection of oligonucleotide targets has been performed with gold nanoparticle probes labeled with oligonucleotides and Raman-active dyes. The gold nanoparticles facilitate the formation of a silver coating that acts as a surface-enhanced Raman scattering promoter for the dye-labeled particles that have been captured by target mols. and an underlying chip in microarray format. The strategy provides the high-sensitivity and high-selectivity attributes of gray-scale scanometric detection but adds multiplexing and ratioing capabilities because a very large no. of probes can be designed based on the concept of using a Raman tag as a narrow-band spectroscopic fingerprint. Six dissimilar DNA targets with six Raman-labeled nanoparticle probes were distinguished, as well as two RNA targets with single nucleotide polymorphisms. The current unoptimized detection limit of this method is 20 femtomolar.
- 57Wang, H.-H.; Cheng, T. Y.; Sharma, P.; Chiang, F. Y.; Chiu, S. W. Y.; Wang, J. K.; Wang, Y. L. Transparent Raman-enhancing substrates for microbiological monitoring and in situ pollutant detection. Nanotechnology 2011, 22, 385702, DOI: 10.1088/0957-4484/22/38/385702Google ScholarThere is no corresponding record for this reference.
- 58Peksa, V.; Jahn, M.; Štolcová, L.; Schulz, V.; Proška, J.; Procházka, M.; Weber, K.; Cialla-May, D.; Popp, J. Quantitative SERS Analysis of Azorubine (E 122) in Sweet Drinks. Anal. Chem. 2015, 87, 2840– 2844, DOI: 10.1021/ac504254kGoogle Scholar58https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXitlKltLo%253D&md5=428328bde5113753a39bed3a3cb01c0dQuantitative SERS Analysis of Azorubine (E 122) in Sweet DrinksPeksa, Vlastimil; Jahn, Martin; Stolcova, Lucie; Schulz, Volker; Proska, Jan; Prochazka, Marek; Weber, Karina; Cialla-May, Dana; Popp, JurgenAnalytical Chemistry (Washington, DC, United States) (2015), 87 (5), 2840-2844CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Considering both the potential effects on human health and the need for knowledge of food compn., quant. detection of synthetic dyes in foodstuffs and beverages is an important issue. For the first time, we report a fast quant. anal. of the food and drink colorant azorubine (E 122) in different types of beverages using surface-enhanced Raman scattering (SERS) without any sample prepn. Seven com. available sweet drinks (including two neg. controls) with high levels of complexity (sugar/artificial sweetener, ethanol content, etc.) were tested. Highly uniform Au "film over nanospheres" (FON) substrates together with use of Raman signal from silicon support as internal intensity std. enabled us to quant. det. the concn. of azorubine in each drink. SERS spectral anal. provided sufficient sensitivity (0.5-500 mg L-1) and detd. azorubine concn. closely correlated with those obtained by a std. HPLC technique. The anal. was direct without the need for any pretreatment of the drinks or Au surface. Our SERS approach is a simple and rapid (35 min) prescan method, which can be easily implemented for a field application and for preliminary testing of food samples.
- 59Nilghaz, A.; Mahdi Mousavi, S.; Amiri, A.; Tian, J.; Cao, R.; Wang, X. Surface-Enhanced Raman Spectroscopy Substrates for Food Safety and Quality Analysis. J. Agric. Food Chem. 2022, 70 (18), 5463– 5476, DOI: 10.1021/acs.jafc.2c00089Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtVyrs7vK&md5=adabfb2f59ed7526cb3be7603efa3476Surface-enhanced raman spectroscopy substrates for food safety and quality analysisNilghaz, Azadeh; Mahdi Mousavi, Seyed; Amiri, Amir; Tian, Junfei; Cao, Rong; Wang, XungaiJournal of Agricultural and Food Chemistry (2022), 70 (18), 5463-5476CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)A review. Surface-enhanced Raman spectroscopy (SERS) has been identified as a fundamental surface-sensitive technique that boosts Raman scattering by adsorbing target mols. on sp. surfaces. The application of SERS highly relies on the development of smart SERS substrates, and thus the fabrication of SERS substrates has been constantly improved. Herein, we investigate the impacts of different substrates on SERS technol. including plasmonic metal nanoparticles, semiconductors, and hybrid systems in quant. food safety and quality anal. We first discuss the fundamentals, substrate designs, and applications of SERS. We then provide a crit. review of the recent progress of SERS in its usage for screening and detecting chem. and biol. contaminants including fungicides, herbicides, insecticides, hazardous colorants, and biohazards in food samples to assess the anal. capabilities of this technol. Finally, we investigate the future trends and provide practical techniques that could be used to fulfill the requirements for rapid anal. of food at a low cost.
- 60Fisher, K. M.; McLeish, J. A.; Jamieson, L. E.; Jiang, J.; Hopgood, J. R.; McLaughlin, S.; Donaldson, K.; Campbell, C. J. SERS as a tool for in vitro toxicology. Faraday Discuss. 2016, 187, 501– 520, DOI: 10.1039/C5FD00216HGoogle ScholarThere is no corresponding record for this reference.
- 61Yang, Y.; Li, Z. Y.; Yamaguchi, K.; Tanemura, M.; Huang, Z. R.; Jiang, D.; Chen, Y.; Zhou, F.; Nogami, M. Controlled fabrication of silver nanoneedles array for SERS and their application in rapid detection of narcotics. Nanoscale 2012, 4 (8), 2663– 2669, DOI: 10.1039/c2nr12110gGoogle ScholarThere is no corresponding record for this reference.
- 62Muehlethaler, C.; Leona, M.; Lombardi, J. R. Review of Surface Enhanced Raman Scattering Applications in Forensic Science. Anal. Chem. 2016, 88 (1), 152– 169, DOI: 10.1021/acs.analchem.5b04131Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFKltb7I&md5=3993b23b7e68eb5ef991996988d691e4Review of Surface Enhanced Raman Scattering Applications in Forensic ScienceMuehlethaler, Cyril; Leona, Marco; Lombardi, John R.Analytical Chemistry (Washington, DC, United States) (2016), 88 (1), 152-169CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)A review. Surface enhanced Raman spectroscopy/scattering (SERS) is a surface-sensitive resonance extension of the std. Raman spectroscopy (RS). It was first obsd. that mols. of interest, when excited in the vicinity of or on rough metal substrates exhibited an increase in Raman scattering up to 10 orders of magnitude. Since its discovery in the 70's, SERS has found increasing value as an anal. tool. Its discriminating power to identify mols. unambiguously is amplified by the enhancement afforded, enabling detection of trace quantities materials.
- 63Cui, X.; Li, J.; Li, Y.; Liu, M.; Qiao, J.; Wang, D.; Cao, H.; He, W.; Feng, Y.; Yang, Z. Detection of glucose in diabetic tears by using gold nanoparticles and MXene composite surface-enhanced Raman scattering substrates. Spectrochim. Acta, Part A 2022, 266, 120432, DOI: 10.1016/j.saa.2021.120432Google Scholar63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitFKltbjM&md5=2a8fae8b8fa15acbab3f4ea2bba3eb04Detection of glucose in diabetic tears by using gold nanoparticles and MXene composite surface-enhanced Raman scattering substratesCui, Xiaoyu; Li, Jinming; Li, Yuting; Liu, Mingyu; Qiao, Jinglong; Wang, Dong; Cao, Hui; He, Wanli; Feng, Yun; Yang, ZhouSpectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy (2022), 266 (), 120432CODEN: SAMCAS; ISSN:1386-1425. (Elsevier B.V.)Diabetes has become one of the three chronic non-communicable diseases threatening human health in the world, and the detection of glucose concn. is of great importance for the prevention and treatment of diabetes. The noninvasive detection of glucose in tears has attracted interest over the past several decades, however, time-consuming, expensive equipment, and specialist technicians make tear anal. still challenging. Here, flexible surface-enhanced Raman scattering (SERS) substrates composed of gold nanoparticles (AuNPs) and two-dimensional MXene Ti3C2TX nanosheets have been designed. The GMXeP (gold nanoparticles with MXene nanosheets loaded on paper) SERS substrates show good sensitivity, reproducibility, and stability, yielding an enhancement factor (EF) of 3.7 x 105 at the concn. of 10-9 M. The GMXeP SERS substrates are used to detect glucose of diabetic tears within a linear range of 1-50μM, the lowest detection concn. is 0.39μM and the significant correlation between tear glucose and blood glucose indicates that this method is suitable for sensitive and noninvasive detection of blood glucose.
- 64Wang, Y.; Zhao, P.; Mao, L.; Hou, Y.; Li, D. Determination of brain injury biomarkers by surface-enhanced Raman scattering using hollow gold nanospheres. RSC Adv. 2018, 8, 3143– 3150, DOI: 10.1039/C7RA12410DGoogle ScholarThere is no corresponding record for this reference.
- 65Zhou, W.; Gao, X.; Liu, D.; Chen, X. Gold Nanoparticles for In Vitro Diagnostics. Chem. Rev. 2015, 115, 10575– 10636, DOI: 10.1021/acs.chemrev.5b00100Google Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVOit7jJ&md5=bc70ccd0e7d5d962ebfa02128539b520Gold Nanoparticles for In Vitro DiagnosticsZhou, Wen; Gao, Xia; Liu, Dingbin; Chen, XiaoyuanChemical Reviews (Washington, DC, United States) (2015), 115 (19), 10575-10636CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. In vitro diagnosis (IVD) show great value in different economic settings. Undoubtedly, the rapid development of nanotechnol. provides significant improvement in IVD systems.
- 66Hidi, I. J.; Jahn, M.; Pletz, M. W.; Weber, K.; Cialla-May, D.; Popp, J. Toward Levofloxacin Monitoring in Human Urine Samples by Employing the LoC-SERS Technique. J. Phys. Chem. C 2016, 120, 20613– 20623, DOI: 10.1021/acs.jpcc.6b01005Google Scholar66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28Xkt1Cgtbk%253D&md5=79c81f25e4416810684819f0596fa760Toward Levofloxacin Monitoring in Human Urine Samples by Employing the LoC-SERS TechniqueHidi, Izabella J.; Jahn, Martin; Pletz, Mathias W.; Weber, Karina; Cialla-May, Dana; Popp, JuergenJournal of Physical Chemistry C (2016), 120 (37), 20613-20623CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The pharmacokinetics of antibiotics such as levofloxacin exhibits large interindividual differences, questioning the value of fixed dose regimens and warranting individual dosing based on therapeutic drug monitoring. Here, in a proof of principal study, it is shown that levofloxacin can be detected in human urine samples by employing lab-on-a-chip surface enhanced Raman spectroscopy (LoC-SERS). First, artificial urine is used as a matrix in order to get insights into the influence of different parameters such as matrix complexity, aggregation time, and matrix diln. on the overall SERS signal. Second, three anonymized individual and three pooled urine samples originating from patients undergoing either no or unknown medical treatments have been spiked with the target analyte. Measurements were performed with a benchtop and a portable Raman setup. In all six samples urinary levofloxacin concns. between 0.45 mM (162.6 μg/mL) and 1.8 mM (650.5 μg/mL) have been successfully detected. According to the literature, the normal levofloxacin concn. in urine is 1.38 mM ± 0.68 mM with a min. measured concn. of 0.45 mM after 4 h from the administration of a 500 mg dose. The presented results therefore show that LoC-SERS is a promising bioanal. tool for urine anal.
- 67Chon, H.; Lee, S.; Yoon, S. Y.; Lee, E. K.; Chang, S. I.; Choo, J. SERS-based competitive immunoassay of troponin I and CK-MB markers for early diagnosis of acute myocardial infarction. Chem. Commun. 2014, 50, 1058– 1060, DOI: 10.1039/C3CC47850EGoogle Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFyrt7vL&md5=575fc2cfc5cb713081a518ef557c2f13SERS-based competitive immunoassay of troponin I and CK-MB markers for early diagnosis of acute myocardial infarctionChon, Hyangah; Lee, Sangyeop; Yoon, Soo-Young; Lee, Eun Kyu; Chang, Soo-Ik; Choo, JaebumChemical Communications (Cambridge, United Kingdom) (2014), 50 (9), 1058-1060CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)We report a SERS-based competitive immunoassay technique for the early diagnosis of acute myocardial infarction (AMI). Simultaneous quantification of the dual cardiac markers, CK-MB and troponin I, was achieved by single wavelength excitation.
- 68Xu, H.; Aizpurua, J.; Kall, M.; Apell, P. Electromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scattering. Phys. Rev. E 2000, 62, 4318– 4324, DOI: 10.1103/PhysRevE.62.4318Google Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3cXmsFShsr0%253D&md5=e345f684a5cfdf4a5ecc455992f56b9eElectromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scatteringXu, Hongxing; Aizpurua, Javier; Kall, Mikael; Apell, PeterPhysical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics (2000), 62 (3-B), 4318-4324CODEN: PLEEE8; ISSN:1063-651X. (American Physical Society)The authors examine whether single mol. sensitivity in surface-enhanced Raman scattering (SERS) can be explained in the framework of classical electromagnetic theory. The influence of colloid particle shape and size, compn. (Ag or Au) and interparticle sepn. distance on the wavelength-dependent SERS enhancement factor is reported. The authors' calcns. indicate that the max. enhancement factor achievable through electromagnetics is of the order 1011. This was obtained only under special circumstances, at interstitial sites between particles and at locations outside sharp surface protrusions. The comparative rarity of such sites, together with the extreme spatial localization of the enhancement they provide, can qual. explain why only very few surface sites seem to contribute to the measured signal in single-mol. SERS expts. Enhancement factors of the order 1014-1015, which are reported in recent expts., probably involve addnl. enhancement mechanisms such as chemisorption induced resonance Raman effects.
- 69Stockman, M. I. Electromagnetic Theory of SERS. In Surface-Enhanced Raman Scattering; Kneipp, K.; Moskovits, M.; Kneipp, H., Eds.; Topics in Applied Physics; Springer: Berlin, Heidelberg, 2006; Vol. 103.Google ScholarThere is no corresponding record for this reference.
- 70Wustholz, K. L.; Brosseau, C. L.; Casadio, F.; Van Duyne, R. P. Surface-enhanced Raman spectroscopy of dyes: from single molecules to the artists’ canvas. Phys. Chem. Chem. Phys. 2009, 11, 7350– 7359, DOI: 10.1039/b904733fGoogle Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtVSmtrvN&md5=d343f6e636ca1c9a33eabeeaf821a354Surface-enhanced Raman spectroscopy of dyes: from single molecules to the artists' canvasWustholz, Kristin L.; Brosseau, Christa L.; Casadio, Francesca; Van Duyne, Richard P.Physical Chemistry Chemical Physics (2009), 11 (34), 7350-7359CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)This perspective presents recent surface-enhanced Raman spectroscopy (SERS) studies of dyes, with applications to the fields of single-mol. spectroscopy and art conservation. First we describe the development and outlook of single-mol. SERS (SMSERS). Rather than providing an exhaustive review of the literature, SMSERS expts. that we consider essential for its future development are emphasized. Shifting from single-mol. to ensemble-averaged expts., we describe recent efforts toward SERS anal. of colorants in precious artworks. Our intention is to illustrate through these examples that the forward development of SERS is dependent upon both fundamental (e.g., SMSERS) and applied (e.g., on-the-specimen SERS of historical art objects) investigations and that the future of SERS is very bright indeed.
- 71Ding, S.-Y.; You, E.-M.; Tian, Z.-Q.; Moskovits, M. Electromagnetic theories of surface-enhanced Raman spectroscopy. Chem. Soc. Rev. 2017, 46, 4042– 4076, DOI: 10.1039/C7CS00238FGoogle Scholar71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVyhtb3M&md5=34de1cd27397af7823bc3667cb945df9Electromagnetic theories of surface-enhanced Raman spectroscopyDing, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, MartinChemical Society Reviews (2017), 46 (13), 4042-4076CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concn. of the electromagnetic (EM) fields assocd. with light in or near appropriately nanostructured elec.-conducting materials, most prominently, but not exclusively high-cond. metals such as silver and gold. This field concn. takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to conc. EM optical fields at locations where mols. of interest reside, and to enhance the radiation efficiency of the oscillating dipoles assocd. with these mols. and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, esp. those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theor. approaches for optimizing nanostructures with hotspots as efficient EM near-field concg. and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estd. Several exptl. strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and esp. to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical strategies for simulating the optical properties and consequential SERS performance of particle-on-substrate systems that might guide the design of SERS-active systems. Finally, some current theor. attempts are briefly discussed for unifying EM and non-EM contribution to SERS.
- 72Schlücker, S. Surface-Enhanced Raman Spectroscopy: Concepts and Chemical Applications. Angew. Chem., Int. Ed. 2014, 53 (19), 4756– 4795, DOI: 10.1002/anie.201205748Google Scholar72https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlvVSntbY%253D&md5=bc6f5d5e61e9d1d5ea168d13cb5193d1Surface-Enhanced Raman Spectroscopy: Concepts and Chemical ApplicationsSchluecker, SebastianAngewandte Chemie, International Edition (2014), 53 (19), 4756-4795CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Surface-enhanced Raman scattering (SERS) has become a mature vibrational spectroscopic technique during the last decades and the no. of applications in the chem., material, and in particular life sciences is rapidly increasing. This Review explains the basic theory of SERS in a brief tutorial and-based on original results from recent research-summarizes fundamental aspects necessary for understanding SERS and provides examples for the prepn. of plasmonic nanostructures for SERS. Chem. applications of SERS are the centerpiece of this Review. They cover a broad range of topics such as catalysis and spectroelectrochem., single-mol. detection, and (bio)anal. chem.
- 73Camden, J. P.; Dieringer, J. A.; Wang, Y.; Masiello, D. J.; Marks, L. D.; Schatz, G. C.; Van Duyne, R. P. Probing the structure of single-molecule surface-enhanced Raman scattering hot spots. J. Am. Chem. Soc. 2008, 130, 12616– 12617, DOI: 10.1021/ja8051427Google Scholar73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtVOqtLjM&md5=2ed76d046d5fedb7fd3c1f72bf7194fbProbing the Structure of Single-Molecule Surface-Enhanced Raman Scattering Hot SpotsCamden, Jon P.; Dieringer, Jon A.; Wang, Yingmin; Masiello, David J.; Marks, Lawrence D.; Schatz, George C.; Van Duyne, Richard P.Journal of the American Chemical Society (2008), 130 (38), 12616-12617CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The authors present here a detailed study of the specific nanoparticle structures that give rise to single-mol. surface-enhanced Raman scattering (SMSERS). A variety of structures are obsd., but the simplest are dimers of Ag nanocrystals. The authors chose one of these structures for detailed study using electrodynamics calcns. and found that the electromagnetic SERS enhancement factors of 109 are easily obtained and are consistent with single-mol. SERS activity.
- 74Rycenga, M.; Camargo, P. H. C.; Li, W.; Moran, C. H.; Xia, Y. Understanding the SERS Effects of Single Silver Nanoparticles and Their Dimers, One at a Time. J. Phys. Chem. Lett. 2010, 1 (4), 696– 703, DOI: 10.1021/jz900286aGoogle Scholar74https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtVGgsL8%253D&md5=72d34e7f1ab39b44d7df4e532756cad5Understanding the SERS Effects of Single Silver Nanoparticles and Their Dimers, One at a TimeRycenga, Matthew; Camargo, Pedro H. C.; Li, Weiyang; Moran, Christine H.; Xia, YounanJournal of Physical Chemistry Letters (2010), 1 (4), 696-703CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)A review. This Perspective article highlights recent developments in a class of surface-enhanced Raman scattering (SERS) expts. that aim to correlate SERS enhancement factors with the phys. parameters of metal nanostructures. In a typical study, the SERS substrate is fabricated by depositing colloidal nanoparticles on a silicon wafer to obtain individual particles isolated from each other or small aggregates such as dimeric units. With the help of registration marks, the same nanoparticle, or dimer of nanoparticles, can be quickly located under a Raman microscope (for SERS spectra) and a scanning electron microscope (for structural characterization). The nanoscale characterization achieved by these studies has resulted in unparalleled investigations into the nature of polarization dependency for SERS, the hot spot nature of single nanoparticles and dimers, and the manipulation of hot spots through shape-controlled synthesis and self-assembly. We discuss the new insights that these studies have offered and the future progress that they can deliver to the advancement of SERS.
- 75Diebold, E. D.; Peng, P.; Mazur, E. Isolating surface-enhanced Raman scattering hot spots using multiphoton lithography. J. Am. Chem. Soc. 2009, 131, 16356– 16357, DOI: 10.1021/ja9073936Google Scholar75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXhtlWlsr%252FN&md5=686764b5c9f62ba3ee9b1486c6f6a72eIsolating surface-enhanced Raman scattering hot spots using multiphoton lithographyDiebold, Eric D.; Peng, Paul; Mazur, EricJournal of the American Chemical Society (2009), 131 (45), 16356-16357CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The authors present a method for improving femtomole-level trace detection (109 mols.) using large-area surface-enhanced Raman scattering (SERS) substrates. Using multiphoton-induced exposure of a com. photoresist, the authors phys. limit the available mol. adsorption sites to only the electromagnetic hot spots on the substrate. This process prevents mols. from adsorbing to sites of weak SERS enhancement, while permitting adsorption to sites of extraordinary SERS enhancement. For a randomly adsorbed submonolayer of benzenethiol mols. the av. Raman scattering cross section of the processed sample is 27 times larger than that of an unprocessed SERS substrate.
- 76Petti, L.; Capasso, R.; Rippa, M.; Pannico, M.; La Manna, P.; Peluso, G.; Calarco, A.; Bobeico, E.; Musto, P. A plasmonic nanostructure fabricated by electron beam lithography as a sensitive and highly homogeneous SERS substrate for bio-sensing applications. Vib. Spectrosc. 2016, 82, 22– 30, DOI: 10.1016/j.vibspec.2015.11.007Google Scholar76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XisFSltrg%253D&md5=e65180045347ef9ce5d33d54435d7d6bA plasmonic nanostructure fabricated by electron beam lithography as a sensitive and highly homogeneous SERS substrate for bio-sensing applicationsPetti, Lucia; Capasso, Rossella; Rippa, Massimo; Pannico, Marianna; La Manna, Pietro; Peluso, Gianfranco; Calarco, Anna; Bobeico, Eugenia; Musto, PellegrinoVibrational Spectroscopy (2016), 82 (), 22-30CODEN: VISPEK; ISSN:0924-2031. (Elsevier B.V.)Surface-enhanced Raman scattering (SERS) on a gold triangular nanoprisms array with precisely controlled size and spacing, fabricated via electron beam lithog. was investigated. This SERS substrate shows reasonable efficiency at 785 nm excitation for the detection of p-mercaptoaniline (pMA), and a remarkable homogeneity of the SERS response over the sensing area. The performances of the engineered SERS substrate with human prostate cancer cells has been tested, highlighting excellent sensitivity in comparison to spontaneous Raman scattering, esp. in the 1500-1700 cm-1 frequency range, characteristic of the peptide linkage and the neighboring functional groups. The results are promising for biosensing applications, provided the selectivity is enhanced by suitable functionalization approaches.
- 77Yue, W.; Wang, Z.; Yang, Y.; Chen, L.; Syed, A.; Wong, K.; Wang, X. Electron-beam lithography of gold nanostructures for surface-enhanced Raman scattering. J. Manuf. Syst. 2012, 22 (12), 125007, DOI: 10.1088/0960-1317/22/12/125007Google ScholarThere is no corresponding record for this reference.
- 78Mikac, L.; Ivanda, M.; Gotić, M.; Mihelj, T.; Horvat, L. Synthesis and characterization of silver colloidal nanoparticles with different coatings for SERS application. J. Nanopart. Res. 2014, 16, 2748, DOI: 10.1007/s11051-014-2748-9Google ScholarThere is no corresponding record for this reference.
- 79Munro, C. H.; Smith, W. E.; Garner, M.; Clarkson, J.; White, P. C. Characterization of the Surface of a Citrate-Reduced Colloid Optimized for Use as a Substrate for Surface-Enhanced Resonance Raman Scattering. Langmuir 1995, 11 (10), 3712– 3720, DOI: 10.1021/la00010a021Google Scholar79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXotlKjsr0%253D&md5=1e08259e678e94e15ef0b9d1651038d5Characterization of the Surface of a Citrate-Reduced Colloid Optimized for Use as a Substrate for Surface-Enhanced Resonance Raman ScatteringMunro, C. H.; Smith, W. E.; Garner, M.; Clarkson, J.; White, P. C.Langmuir (1995), 11 (10), 3712-20CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Citrate-reduced colloids can be used to give reproducible, sensitive, and selective anal. by surface-enhanced (resonance) Raman scattering (SE(R)RS). Control of the chem. at the colloid surface is essential to realize the potential of this method. This study is aimed at understanding the surface chem. in aq. solns., characterizing the nature of the final surface, and developing a robust method for SE(R)RS anal. at the surface. An optimized procedure for the redn. of silver nitrate with trisodium citrate is described. Visible absorption and photon correlation spectroscopies of colloid formation indicate that the initial redn. of AgI to Ag0 occurs within 2 min of citrate addn., and the initial particles formed are large (60-80 nm) and polydisperse. Subsequent heating initially provides a less polydisperse mixt. of 20-30 and 40-50 nm particles and finally an approx. monodisperse distribution of smaller particles (∼27 nm). Soln. NMR studies of the colloidal suspension indicate the presence of citrate and its decompn. products, acetoacetic acid and formate in soln. throughout colloid formation. Raman scattering from aggregated aliquots of colloid indicates two forms of citrate depending on the stage of prepn., but neither acetoacetic acid nor formate is detected as being adsorbed at the silver surface. The final, approx. monodisperse particles are believed to be stabilized by a surface layer of silver citrate, with pendant neg. groups. The colloids are stable for over 2 mo. The SE(R)RS effect requires controlled aggregation of the colloid. The aggregation process is generally induced by the addn. of acid or activating ions, for example, Cl- or I-. Aggregation with acid (HNO3) and with poly(L-lysine) and ascorbic acid are compared. The poly(L-lysine) method is more effective, enhancing the monodispersity of colloidal aggregates. The reproducibility of SERRS (relative std. deviation (RSD) < 5%) is acceptable for anal. purposes, whereas that from aggregation with acid (HNO3) (RSD = 18.5%) is not. Furthermore, at low analyte concns., SE(R)RS from both the analyte and the citrate layer are obsd. on aggregation with nitric acid. However, SE(R)RS is only obsd. from the analyte on aggregation with poly(L-lysine) and ascorbic acid. The advantages for trace anal. of anionic, neutral, and cationic species of using reagents which alter surface charge and dielec. const. are illustrated.
- 80Athira, K.; Ranjana, M.; Bharathi, M. S. S.; Narasimha Reddy, B.; Satheesh Babu, T.; Venugopal Rao, S.; Ravi Kumar, D. V. Aggregation induced, formaldehyde tailored nanowire like networks of Cu and their SERS activity. Chem. Phys. Lett. 2020, 748, 137390, DOI: 10.1016/j.cplett.2020.137390Google ScholarThere is no corresponding record for this reference.
- 81Chang, Y.-L.; Su, C.-J.; Lu, L.-C.; Wan, D. Aluminum Plasmonic Nanoclusters for Paper-Based Surface-Enhanced Raman Spectroscopy. Anal. Chem. 2022, 94 (47), 16319– 16327, DOI: 10.1021/acs.analchem.2c03014Google Scholar81https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivVCktb7K&md5=e9c3a87fff90ea2bc47c2c6ba6d69a39Aluminum Plasmonic Nanoclusters for Paper-Based Surface-Enhanced Raman SpectroscopyChang, Yu-Ling; Su, Chiao-Jung; Lu, Li-Chia; Wan, DehuiAnalytical Chemistry (Washington, DC, United States) (2022), 94 (47), 16319-16327CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Although surface-enhanced Raman spectroscopy (SERS) can rapidly identify mol. fingerprints and has great potential for anal., the need for delicate plasmonic substrates and complex lab. instruments seriously limits its applicability for on-site detection. This paper describes the development of an inexpensive aluminum nanoparticle (AlNP)-decorated paper that functions as a facile SERS-based detection platform (Al-PSERS). Polydopamine-protected AlNPs were chem. synthesized and then simply drop-cast onto a hydrophobic cellulose paper, forming a monolayer AlNP cluster array. Because of the abundance of hot spots arising from the plasmonic clusters, the inherent quasi-three-dimensional structure of the cellulose fibers, and the concn. effect of the hydrophobic surface, the Al-PSERS provided significant enhancements to the signal of various analytes, measured using a portable 785 nm Raman spectrometer. Near-field optical simulations and exptl. spectroscopic results revealed that the local elec. fields and corresponding SERS signal intensities of the AlNP array exhibited clear particle-length and cluster-size dependencies. Therefore, the Al-PSERS could be optimized to provide high sensitivity (enhancement factor: 2 x 103) and excellent reproducibility (variation: 8.72%). Moreover, the optimal Al-PSERS was capable of detecting colorants and environmental pollutants; for example, the detection limits of allura red and benzo[a]pyrene reached as low as 3.5 and 0.15 ppm, resp. Furthermore, the Al-PSERS could rapidly identify illegal (rhodamine B) and edible (allura red, erythrosine) colorants from a mixt. of multiple colorants or from adulterated candies. Because it facilitates rapid detection, is of low cost, and has minimal tech. requirements, Al-PSERS should be applicable to on-site detection in, for example, food inspection and environmental monitoring.
- 82Cai, W.; Ren, B.; Li, X.; She, C.; Liu, F.; Cai, X.; Tian, Z. Investigation of surface-enhanced Raman scattering from platinum electrodes using a confocal Raman microscope: Dependence of surface roughening pretreatment. Surf. Sci. 1998, 406, 9– 22, DOI: 10.1016/S0039-6028(97)01030-3Google Scholar82https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXksFKiu74%253D&md5=ffefbece8594afc96830091b512516eeInvestigation of surface-enhanced Raman scattering from platinum electrodes using a confocal raman microscope: dependence of surface roughening pretreatmentCai, W. B.; Ren, B.; Li, X. Q.; She, C. X.; Liu, F. M.; Ca, X. W.; Tian, Z. Q.Surface Science (1998), 406 (1-3), 9-22CODEN: SUSCAS; ISSN:0039-6028. (Elsevier Science B.V.)In order to establish an appropriate surface roughening procedure for obtaining high-quality surface Raman spectra from Pt electrodes, various roughening conditions for the SERS from the adsorbed pyridine, thiocyanate and hydrogen are assessed in terms of the corresponding surface Raman intensities, enhancement factors and surface homogeneity. The repetitive square-wave oxidn. redn. cycle (SWORC), triangular-wave ORC (TWORC) and platinization have been performed in the present study. The enhancement factor (G) is calcd. based on the confocal feature of a confocal microprobe Raman system, showing one to two orders of amplification of Raman signal for adsorbed pyridine on roughened Pt surfaces. The involvement of charge transfer (CT) enhancement is inferred from the SERS intensity-potential profiles that are dependent on excitation lines. In general, the Pt surfaces with different roughness factors (R) can be divided into three categories: (I) the mildly roughened surface with R of 20-30 seems more adequate for the study of SERS mechanism including calcn. of G; (2) the moderately roughened surface with R ranging from 20 to 100, providing homogeneous morphologies, is suitable for investigating surface adsorption and reactions; (3) the highly roughened surface with R ranging from 100 to 300, with non-uniform morphologies, could only be used for investigating species having small Raman cross-sections such as hydrogen adsorption.
- 83Liu, Z.; Yang, Z.; Cui, L.; Ren, B.; Tian, Z. Electrochemically roughened palladium electrodes for surface-enhanced Raman spectroscopy: Methodology, mechanism, and application. J. Phys. Chem. C 2007, 111, 1770– 1775, DOI: 10.1021/jp066122gGoogle Scholar83https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXjtVWqug%253D%253D&md5=2f6c77a87b6a45e45093411087e30d4bElectrochemically Roughened Palladium Electrodes for Surface-Enhanced Raman Spectroscopy: Methodology, Mechanism, and ApplicationLiu, Zheng; Yang, Zhi-Lin; Cui, Li; Ren, Bin; Tian, Zhong-QunJournal of Physical Chemistry C (2007), 111 (4), 1770-1775CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Pd is one of the important materials in surface sciences due to its unique catalytic activities toward various reactions. To study the process occurring on the Pd surface by Raman spectroscopy, it is necessary to obtain a surface with surface-enhanced Raman scattering (SERS) activity. The authors reported here the prepn. method for obtaining SERS-active pure massive Pd electrodes via an electrochem. roughening method by strictly controlling the roughening potential and frequency. The roughened surface consists mostly of spherical nanoparticles with a diam. of 50-60 nm. The SERS activity of the electrode was demonstrated by using pyridine as a model mol., and the surface enhancement could be ≤3 orders of magnitude. With such high enhancement, the authors were able to study processes related to mols. with small Raman cross sections, such as CO. Distinctly different from other transition metals in the VIIIB group, Pd electrode shows SERS activity clearly dependent on the wavelength of the excitation laser, with highest enhancement appearing at 632.8 nm. To understand the enhancement mechanism, a finite difference time domain method was used to simulate the optical properties of the roughened Pd surface, and electromagnetic enhancement plays an important role in the SERS of the Pd, which is in good agreement with the exptl. result.
- 84Guo, L.; Huang, Q.; Li, X.-Y.; Yang, S. Iron nanoparticles: Synthesis and applications in surface enhanced Raman scattering and electrocatalysis. Phys. Chem. Chem. Phys. 2001, 3, 1661– 1665, DOI: 10.1039/b009951lGoogle Scholar84https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD3MXis1Sitr0%253D&md5=e7d4e0eb8e7ba94461d6389c570edbdaIron nanoparticles: Synthesis and applications in surface enhanced Raman scattering and electrocatalysisGuo, Lin; Huang, Qunjian; Li, Xiao-yuan; Yang, ShihePhysical Chemistry Chemical Physics (2001), 3 (9), 1661-1665CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)The microemulsion method is employed to synthesize iron nanoparticles with an av. size of ∼3 nm using trioctyl phosphine oxide (TOPO) as a stabilizing agent. The morphol., structure, and compn. of the nanoparticles are studied by transmission electron microscopy (TEM), XPS (XPS) and UV-VIS spectroscopy. The iron nanoparticles show a remarkable surface-enhanced Raman scattering (SERS) activity, and the scheme of iron nanoparticle-on-electrode is successfully used in the in situ SERS study of adsorbed mols. Electrocatalysis over the iron nanoparticles is demonstrated in the highly efficient and selective redn. of H2O2 in the presence of oxygen.
- 85Zhang, C.; Jiang, S. Z.; Yang, C.; Li, C. H.; Huo, Y. Y.; Liu, X. Y.; Liu, A. H.; Wei, Q.; Gao, S. S.; Gao, X. G.; Man, B. Y. Gold@silver bimetal nanoparticles/pyramidal silicon 3D substrate with high reproducibility for high-performance SERS. Sci. Rep. 2016, 6, 25243, DOI: 10.1038/srep25243Google Scholar85https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XnsVemsrk%253D&md5=decb79ec8ead560ef52f3d94d25ae843Gold@silver bimetal nanoparticles/pyramidal silicon 3D substrate with high reproducibility for high-performance SERSZhang, Chao; Jiang, Shou Zhen; Yang, Cheng; Li, Chong Hui; Huo, Yan Yan; Liu, Xiao Yun; Liu, Ai Hua; Wei, Qin; Gao, Sai Sai; Gao, Xing Guo; Man, Bao YuanScientific Reports (2016), 6 (), 25243CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)A novel and efficient surface enhanced Raman scattering (SERS) substrate has been presented based on Gold@silver/pyramidal silicon 3D substrate (Au@Ag/3D-Si). By combining the SERS activity of Ag, the chem. stability of Au and the large field enhancement of 3D-Si, the Au@Ag/3D-Si substrate possesses perfect sensitivity, homogeneity, reproducibility and chem. stability. Using R6G as probe mol., the SERS results imply that the Au@Ag/3D-Si substrate is superior to the 3D-Si, Ag/3D-Si and Au/3D-Si substrate. We also confirmed these excellent behaviors in theory via a com. COMSOL software. The corresponding exptl. and theor. results indicate that our proposed Au@Ag/3D-Si substrate is expected to develop new opportunities for label-free SERS detections in biol. sensors, biomedical diagnostics and food safety.
- 86Zhang, T.; Sun, Y.; Hang, L.; Li, H.; Liu, G.; Zhang, X.; Lyu, X.; Cai, W.; Li, Y. Periodic Porous Alloyed Au–Ag Nanosphere Arrays and Their Highly Sensitive SERS Performance with Good Reproducibility and High Density of Hotspots. ACS Appl. Mater. Interfaces 2018, 10 (11), 9792– 9801, DOI: 10.1021/acsami.7b17461Google Scholar86https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtlOqs7Y%253D&md5=ae02f2eb5d6d50d68b99ed6a9bcacaa7Periodic porous alloyed Au-Ag nanosphere arrays and highly densitive SERS performance with good reproducibility and high density of hotspotsZhang, Tao; Sun, Yiqiang; Hang, Lifeng; Li, Huilin; Liu, Guangqiang; Zhang, Xiaomin; Lyu, Xianjun; Cai, Weiping; Li, YueACS Applied Materials & Interfaces (2018), 10 (11), 9792-9801CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Periodic porous alloyed Au-Ag nanosphere (NS) arrays with different periodic lengths and tunable compn. ratios were prepd. on Si substrates on a large scale (∼cm2) using stepwise metal deposition-annealing and subsequent chem. corrosion from a monolayer of colloidal polystyrene (PS) microspheres as the initial template. The porous alloyed Au-Ag NSs possessed a high porosity and bicontinuous morphol. composed of hierarchically interconnected ligaments, which were obtained from an optimized dealloying process in nitric acid. Interestingly, when the dealloying time was prolonged, the av. size of the porous alloyed NSs slightly decreased, and the width of the ligaments gradually increased. The periodic length of the array could be facilely changed by controlling the initial particle size of the PS template. Moreover, the porous alloyed Au-Ag NS arrays were explored as a platform for the surface-enhanced Raman scattering (SERS) detection of 4-aminothiophenol (4-ATP) and exhibited excellent reproducibility and high sensitivity because of the periodic structure of the arrays and the abundance of inherent "hotspots". After optimization expts., a low concn. of 10-10 M 4-ATP could be detected on these porous Au-Ag NS array substrates. Such highly reproducible SERS activity is meaningful for improving the practical application of portable Raman detection equipment.
- 87Capaccio, A.; Sasso, A.; Rusciano, G. A simple and reliable approach for the fabrication of nanoporous silver patterns for surface-enhanced Raman spectroscopy applications. Sci. Rep. 2021, 11, 22295, DOI: 10.1038/s41598-021-01727-zGoogle ScholarThere is no corresponding record for this reference.
- 88Wang, B.; Zhang, L.; Zhou, X. Synthesis of silver nanocubes as a SERS substrate for the determination of pesticide paraoxon and thiram. Spectrochim. Acta, Part A 2014, 121, 63– 69, DOI: 10.1016/j.saa.2013.10.013Google Scholar88https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtFOgs7w%253D&md5=08d637ec737175ebbf5e10dd3040f906Synthesis of silver nanocubes as a SERS substrate for the determination of pesticide paraoxon and thiramWang, Bin; Zhang, Li; Zhou, XiaSpectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy (2014), 121 (), 63-69CODEN: SAMCAS; ISSN:1386-1425. (Elsevier B.V.)The silver cube-like nanostructure with uniform size and high yield have been synthesized through the rapid sulfide-mediated polyol method. The morphol., structure and optical properties of the as-prepd. silver nanocubes were characterized by UV-Visible spectroscopy, field emission SEM (FESEM) and X-ray diffraction (XRD). The Surface-Enhanced Raman Scattering (SERS) performance of the as-prepd. Ag nanocubes was characterized by crystal violet (CV) as the probe mols. Furthermore, the low levels of thiram and pesticide paraoxon can be detected by the SERS technique, which shows that the silver nanocubes as a SERS substrate have excellent sensitivity and reproducibility.
- 89Saute, B.; Premasiri, R.; Ziegler, L.; Narayanan, R. Gold nanorods as surface enhanced Raman spectroscopy substrates for sensitive and selective detection of ultra-low levels of dithiocarbamate pesticides. Analyst 2012, 137, 5082– 5087, DOI: 10.1039/c2an36047kGoogle Scholar89https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsVCqtbfK&md5=b745bbf918823b053b5697dd367e2882Gold nanorods as surface enhanced Raman spectroscopy substrates for sensitive and selective detection of ultra-low levels of dithiocarbamate pesticidesSaute, Benjamin; Premasiri, Ranjith; Ziegler, Lawrence; Narayanan, RadhaAnalyst (Cambridge, United Kingdom) (2012), 137 (21), 5082-5087CODEN: ANALAO; ISSN:0003-2654. (Royal Society of Chemistry)We report the use of gold nanorods as soln.-based SERS substrates for the detection of ultralow-levels of three different dithiocarbamate fungicides: thiram, ferbam and ziram. Gold nanorods are attractive to use as SERS substrates due to the ability to tune the surface plasmon resonance of the nanoparticles to the laser excitation wavelength of the Raman spectrometer equipped with a 785 nm diode laser. The gold nanorods are synthesized using a seed-mediated growth method and characterized using UV-Visible spectroscopy, zeta potential, and TEM. The gold nanorods have an aspect ratio of 2.19 ± 0.21 and have an av. length of 37.81 ± 4.83 nm. SERS spectra are acquired at different concns. of each fungicide and calibration curves are obtained by monitoring the intensity of the band arising from the ν(C-N) stretching mode coupled to the sym. δ(CH3) motion. The limits of detection and limits of quantitation are obtained for each fungicide. The limits of detection are 11.00 ± 0.95 nM, 8.00 ± 1.01 nM, and 4.20 ± 1.22 nM for thiram, ferbam, and ziram resp. The limits of quantitation are 34.43 ± 0.95 nM, 25.61 ± 1.01 nM, and 12.94 ± 1.22 nM for thiram, ferbam, and ziram resp. It can be seen that the three different dithiocarbamates can be detected in the low nM range based on the limits of detection that are achieved.
- 90Khoury, C. G.; Vo-Dinh, T. Gold Nanostars For Surface-Enhanced Raman Scattering: Synthesis, Characterization and Optimization. J. Phys. Chem. C 2008, 112 (48), 18849– 18859, DOI: 10.1021/jp8054747Google Scholar90https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtlemtrjP&md5=38b0674fd07786695730a28461540dcaGold Nanostars For Surface-Enhanced Raman Scattering: Synthesis, Characterization and OptimizationKhoury, Christopher G.; Vo-Dinh, TuanJournal of Physical Chemistry C (2008), 112 (48), 18849-18859CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The controlled synthesis of high-yield Au nanostars of varying sizes, their characterization, and their use in SERS measurements are reported. Au nanostars ranging from 45 to 116 nm in size were synthesized in high yield, geometrically and statistically modeled, and optically characterized using transmission and SEM and UV-visible absorption spectroscopy. The nanostar characterization involved studying both morphol. evolution over time and size as a function of nucleation (injected seed vol.). The nanostar properties as substrates for SERS were studied and compared with respect to size. As the overall star size increases, so does the core size, the no. of branches and branch aspect ratio; the no. of branch tips per star surface area decreases with increasing size. The stars become more inhomogeneous in shape, although their yield is high and overall size remains homogeneous. Variations in star size are also accompanied by shifts of the long plasmon band in the NIR region, which hints toward tuning capabilities that may be exploited in specific SERS applications. The measured SERS enhancement factors suggest an interesting correlation between nanostar size and SERS efficiencies and were relatively consistent across different star samples, with the enhancement factor estd. as 5 × 103 averaged over the 52-nm nanostars for 633-nm excitation.
- 91Tao, Q.; Li, S.; Ma, C.; Liu, K.; Zhang, Q.-Y. A highly sensitive and recyclable SERS substrate based on Ag-nanoparticle-decorated ZnO nanoflowers in ordered arrays. Dalton Trans. 2015, 44, 3447– 3453, DOI: 10.1039/C4DT03596HGoogle Scholar91https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXktFequg%253D%253D&md5=768e1912a4ba7ce4e2689f8970b427e5A highly sensitive and recyclable SERS substrate based on Ag-nanoparticle-decorated ZnO nanoflowers in ordered arraysTao, Qiang; Li, Shuai; Ma, Chunyu; Liu, Kun; Zhang, Qing-YuDalton Transactions (2015), 44 (7), 3447-3453CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)Using a patterned sapphire substrate with a hemisphere array, flower-like ZnO nanorods grouped in a highly ordered array were fabricated on the wafer scale by routine soln. growth. After decorating with high-d. Ag nanoparticles (NPs), the ZnO nanoflower arrays were used as the substrates for surface enhanced Raman scattering (SERS). Using Rhodamine 6G as the probe mols. with a concn. down to 10-10 M, the SERS substrates present a Raman enhancement as high as 1010 with good reproducibility. The influence of Ag NP decoration on the SERS activity was explored and the sub-10 nm nanogaps between the adjacent Ag NPs were proved to be the primary electromagnetic "hot spots" responsible for the significant Raman enhancement. The Ag-NP-decorated ZnO nanoflower arrays were demonstrated to possess a self-cleaning function enabled by UV irradn. via photocatalytic degrdn. of the analyte mols. In addn., the SERS substrate exhibited an extremely long service lifetime, possibly due to its superhydrophobicity and storage in the dark and a dry environment.
- 92Taylor, A. B.; Siddiquee, A. M.; Chon, J. W. M. Below melting point photothermal reshaping of single gold nanorods driven by surface diffusion. ACS Nano 2014, 8 (12), 12071– 12079, DOI: 10.1021/nn5055283Google Scholar92https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhvFGgu7vJ&md5=3676ccfe6a7d6de67ac2924e57c14977Below Melting Point Photothermal Reshaping of Single Gold Nanorods Driven by Surface DiffusionTaylor, Adam B.; Siddiquee, Arif M.; Chon, James W. M.ACS Nano (2014), 8 (12), 12071-12079CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Plasmonic Au nanorod instability and reshaping behavior below m.ps. are important for many future applications but are yet to be fully understood, with existing nanoparticle melting theories unable to explain the observations. Here, the authors have systematically studied the photothermal reshaping behavior of Au nanorods irradiated with femtosecond laser pulses to report that the instability is driven by curvature-induced surface diffusion rather than a threshold melting process, and that the stability dramatically decreases with increasing aspect ratio. The authors successfully used the surface diffusion model to explain the observations and found that the activation energy for surface diffusion was dependent on the aspect ratio of the rods, from 0.6 eV for aspect ratio of 5 to 1.5 eV for aspect ratio <3. The surface atoms are much easier to diffuse around in larger aspect ratio rods than in shorter rods and can induce reshaping at any given temp. Current plasmonics and nanorod applications with the sharp geometric features used for greater field enhancement will therefore need to consider surface diffusion driven shape change even at low temps.
- 93Tang, L.; Li, S.; Han, F.; Liu, L.; Xu, L.; Ma, W.; Kuang, H.; Li, A.; Wang, L.; Xu, C. SERS-active Au@Ag nanorod dimers for ultrasensitive dopamine detection. Biosens. Bioelectron. 2015, 71, 7– 12, DOI: 10.1016/j.bios.2015.04.013Google Scholar93https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXpsFektb4%253D&md5=a96e06fb12851d38c7da986b2cd5c4fdSERS-active Au@Ag nanorod dimers for ultrasensitive dopamine detectionTang, Lijuan; Li, Si; Han, Fei; Liu, Liqiang; Xu, Liguang; Ma, Wei; Kuang, Hua; Li, Aike; Wang, Libing; Xu, ChuanlaiBiosensors & Bioelectronics (2015), 71 (), 7-12CODEN: BBIOE4; ISSN:0956-5663. (Elsevier B.V.)Dopamine (DA) is a neurotransmitter which plays a key role in the life science. Self-assembled Au@Ag nanorod dimers based on aptamers were developed for ultrasensitive dopamine detection. The electronic field was significantly enhanced by the addn. of silver shell coating on the surface of Au NR dimer. The results displayed that Au@Ag NR dimers were ideal building blocks for constructing the SERS substrates with prominent Raman enhancement effects. It was found that with using this Surface-enhanced Raman scattering (SERS)-encoded this sensing system, a limit of detection of 0.006 pM and a wide linear range of 0.01-10 pM for dopamine detection were obtained. Our work open up a new avenue for the diagnosis and drug-discovery programs.
- 94Zhang, L.-F.; Zhong, S.-L.; Xu, A.-W. Highly branched concave Au/Pd bimetallic nanocrystals with superior electrocatalytic activity and highly efficient SERS enhancement. Angew. Chem. Int. Ed. 2013, 52 (2), 645– 649, DOI: 10.1002/anie.201205279Google Scholar94https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslKntrrE&md5=e27d5dd6b407a95a46ac54680b8d68eeHighly Branched Concave Au/Pd Bimetallic Nanocrystals with Superior Electrocatalytic Activity and Highly Efficient SERS EnhancementZhang, Lin-Fei; Zhong, Sheng-Liang; Xu, An-WuAngewandte Chemie, International Edition (2013), 52 (2), 645-649CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Authors described the synthesis of highly branched concave Au/Pumped bimetallic nanocrystals with high index faces by sedimential growth in aq. soln. at room temp. A large no. of tips and edges are obsd. in the branched structure and the growth mechanism of the evolution of this structure was proposed. The obtained particles were characterized by much better catalytic activity than spherical catalysts. The plasmonic properties and SERS activities were also investigated and these particles showed the SERS enhancement.
- 95Zhang, C.; Jiang, S. Z.; Yang, C.; Li, C. H.; Huo, Y. Y.; Liu, X. Y.; Liu, A. H.; Wei, Q.; Gao, S. S.; Gao, X. G. Gold@silver bimetal nanoparticles/pyramidal silicon 3D substrate with high reproducibility for high-performance SERS. Sci. Rep. 2016, 6, 25243, DOI: 10.1038/srep25243Google Scholar95https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XnsVemsrk%253D&md5=decb79ec8ead560ef52f3d94d25ae843Gold@silver bimetal nanoparticles/pyramidal silicon 3D substrate with high reproducibility for high-performance SERSZhang, Chao; Jiang, Shou Zhen; Yang, Cheng; Li, Chong Hui; Huo, Yan Yan; Liu, Xiao Yun; Liu, Ai Hua; Wei, Qin; Gao, Sai Sai; Gao, Xing Guo; Man, Bao YuanScientific Reports (2016), 6 (), 25243CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)A novel and efficient surface enhanced Raman scattering (SERS) substrate has been presented based on Gold@silver/pyramidal silicon 3D substrate (Au@Ag/3D-Si). By combining the SERS activity of Ag, the chem. stability of Au and the large field enhancement of 3D-Si, the Au@Ag/3D-Si substrate possesses perfect sensitivity, homogeneity, reproducibility and chem. stability. Using R6G as probe mol., the SERS results imply that the Au@Ag/3D-Si substrate is superior to the 3D-Si, Ag/3D-Si and Au/3D-Si substrate. We also confirmed these excellent behaviors in theory via a com. COMSOL software. The corresponding exptl. and theor. results indicate that our proposed Au@Ag/3D-Si substrate is expected to develop new opportunities for label-free SERS detections in biol. sensors, biomedical diagnostics and food safety.
- 96Shen, J.; Su, J.; Yan, J.; Zhao, B.; Wang, D.; Wang, S.; Li, K.; Liu, M.; He, Y.; Mathur, S. Bimetallic nano-mushrooms with DNA-mediated interior nanogaps for high-efficiency SERS signal amplification. Nano Res. 2015, 8 (3), 731– 742, DOI: 10.1007/s12274-014-0556-2Google Scholar96https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhs1Wrtb7N&md5=838a34da7e05f88ef4a4184c0d496569Bimetallic nano-mushrooms with DNA-mediated interior nanogaps for high-efficiency SERS signal amplificationShen, Jianlei; Su, Jing; Yan, Juan; Zhao, Bin; Wang, Dongfang; Wang, Siyi; Li, Kun; Liu, Mengmeng; He, Yao; Mathur, Sanjay; Fan, Chunhai; Song, ShipingNano Research (2015), 8 (3), 731-742CODEN: NRAEB5; ISSN:1998-0000. (Springer GmbH)Uniform silver-contg. metal nanostructures with well-defined nanogaps hold great promise for ultrasensitive surface-enhanced Raman scattering (SERS) analyses. Nevertheless, the direct synthesis of such nanostructures with strong and stable SERS signals remains extremely challenging. Here, we report a DNA-mediated approach for the direct synthesis of gold-silver nano-mushrooms with interior nanogaps. The SERS intensities of these nano-mushrooms were critically dependent on the area of the nanogap between the gold head and the silver cap. We found that the formation of nanogaps was finely tunable by controlling the surface d. of 6-carboxy-X-rhodamine (ROX) labeled single-stranded DNA (ssDNA) on the gold nanoparticles. We obtained nano-mushrooms in high yield with a high SERS signal enhancement factor of ∼1.0 × 109, much higher than that for Au-Ag nanostructures without nanogaps. Measurements for single nanomushrooms show that these structures have both sensitive and reproducible SERS signals.
- 97Khaywah, M. Y.; Jradi, S.; Louarn, G.; Lacroute, Y.; Toufaily, J.; Hamieh, T.; Adam, P. M. Ultrastable, uniform, reproducible, and highly sensitive bimetallic nanoparticles as reliable large scale SERS substrates. J. Phys. Chem. C 2015, 119 (46), 26091– 26100, DOI: 10.1021/acs.jpcc.5b04914Google ScholarThere is no corresponding record for this reference.
- 98Rao, V. K.; Radhakrishnan, T. P. Tuning the SERS response with Ag-Au nanoparticle-embedded polymer thin film substrates. ACS Appl. Mater. Interfaces 2015, 7, 12767– 12773, DOI: 10.1021/acsami.5b04180Google Scholar98https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXpsFOgurs%253D&md5=662ddcf84bf34500a0b73a6c8bc474b3Tuning the SERS Response with Ag-Au Nanoparticle-Embedded Polymer Thin Film SubstratesRao, V. Kesava; Radhakrishnan, T. P.ACS Applied Materials & Interfaces (2015), 7 (23), 12767-12773CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Development of facile routes to the fabrication of film substrates with tunable surface enhanced Raman scattering (SERS) efficiency and identification of the optimal conditions for maximizing the enhancement factor (EF) are significant in terms of both fundamental and application aspects of SERS. Polymer films with embedded bimetallic nanoparticles of Ag-Au are fabricated by a simple 2-stage protocol. Ag nanoparticles are formed in the 1st stage, by the in situ redn. of AgNO3 by the poly(vinyl alc.) (PVA) film through mild thermal annealing, without any addnl. reducing agent. In the 2nd stage, aq. solns. of HAuCl4 spread on the Ag-PVA film under ambient conditions, lead to the galvanic displacement of Ag by Au in situ inside the film, and the formation of Ag-Au particles. Evolution of the morphol. of the bimetallic nanoparticles into hollow cage structures and the distribution of Au on the nanoparticles are revealed through electron microscopy and energy dispersive x-ray spectroscopy. The localized surface plasmon resonance (LSPR) extinction of the nanocomposite thin film evolves with the Ag-Au compn.; theor. simulation of the extinction spectra provides insight into the obsd. trends. The Ag-Au-PVA thin films are efficient substrates for SERS. The EF follows the variation of the LSPR extinction vis-´a-vis the excitation laser wavelength, but with an offset, and the max. SERS effect is obtained at very low Au content; expts. with Rhodamine 6G showed EFs ∼108 and a limit of detection of 0.6 pmol. The present study describes a facile and simple fabrication of a nanocomposite thin film that can be conveniently deployed in SERS studies, and the utility of the bimetallic system to tune and maximize the EF.
- 99Albe, K.; Klein, A. Density-functional-theory calculations of electronic band structure of single-crystal and single-layer WS2. Phys. Rev. B 2002, 66, 073413, DOI: 10.1103/physrevb.66.073413Google ScholarThere is no corresponding record for this reference.
- 100Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically Thin MoS2: A New Direct-Gap Semiconductor. Phys. Rev. Lett. 2010, 105, 136805, DOI: 10.1103/PhysRevLett.105.136805Google Scholar100https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXht1Chs7zL&md5=f29a2e9692fc341d1b921f7862cf4c2aAtomically Thin MoS2. A New Direct-Gap SemiconductorMak, Kin Fai; Lee, Changgu; Hone, James; Shan, Jie; Heinz, Tony F.Physical Review Letters (2010), 105 (13), 136805/1-136805/4CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)The electronic properties of ultrathin crystals of MoS2 consisting of N = 1, 2,...,6 S-Mo-S monolayers were investigated by optical spectroscopy. Through characterization by absorption, photoluminescence, and photocond. spectroscopy, we trace the effect of quantum confinement on the material's electronic structure. With decreasing thickness, the indirect band gap, which lies below the direct gap in the bulk material, shifts upwards in energy by >0.6 eV. This leads to a crossover to a direct-gap material in the limit of the single monolayer. Unlike the bulk material, the MoS2 monolayer emits light strongly. The freestanding monolayer exhibits an increase in luminescence quantum efficiency by more than a factor of 104 compared with the bulk material.
- 101Ding, Y.; Wang, Y.; Ni, J.; Shi, L.; Shi, S.; Tang, W. First principles study of structural, vibrational and electronic properties of graphene-like MX(2) (M = Mo, Nb, W, Ta; X = S, Se, Te) monolayers. Phys. B 2011, 406, 2254– 2260, DOI: 10.1016/j.physb.2011.03.044Google Scholar101https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXltFaktLs%253D&md5=dcf500ebae025ac2c6e3a511b3d7f945First principles study of structural, vibrational and electronic properties of graphene-like MX2 (M=Mo, Nb, W, Ta; X=S, Se, Te) monolayersDing, Yi; Wang, Yanli; Ni, Jun; Shi, Lin; Shi, Siqi; Tang, WeihuaPhysica B: Condensed Matter (Amsterdam, Netherlands) (2011), 406 (11), 2254-2260CODEN: PHYBE3; ISSN:0921-4526. (Elsevier B.V.)Using first principles calcns., we investigate the structural, vibrational and electronic structures of the monolayer graphene-like transition-metal dichalcogenide (MX2) sheets. We find the lattice parameters and stabilities of the MX2 sheets are mainly detd. by the chalcogen atoms, while the electronic properties depend on the metal atoms. The NbS2 and TaS2 sheets have comparable energetic stabilities to the synthesized MoS2 and WS2 ones. The molybdenum and tungsten dichalcogenide (MoX2 and WX2) sheets have similar lattice parameters, vibrational modes, and electronic structures. These analogies also exist between the niobium and tantalum dichalcogenide (NbX2 and TaX2) sheets. However, the NbX2 and TaX2 sheets are metals, while the MoX2 and WX2 ones are semiconductors with direct-band gaps. When the Nb and Ta atoms are doped into the MoS2 and WS2 sheets, a semiconductor-to-metal transition occurs. Comparing to the bulk compds., these monolayer sheets have similar structural parameters and properties, but their vibrational and electronic properties are varied and have special characteristics. Our results suggest that the graphene-like MX2 sheets have potential applications in nano-electronics and nano-devices.
- 102Ma, Y.; Dai, Y.; Guo, M.; Niu, C.; Lu, J.; Huang, B. Electronic and magnetic properties of perfect, vacancy-doped, and nonmetal adsorbed MoSe(2), MoTe(2) and WS(2) monolayers. Phys. Chem. Chem. Phys. 2011, 13, 15546– 15553, DOI: 10.1039/c1cp21159eGoogle Scholar102https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGis7zE&md5=1ec19ba5b7db9677288e776c828756bcElectronic and magnetic properties of perfect, vacancy-doped, and nonmetal adsorbed MoSe2, MoTe2 and WS2 monolayersMa, Yandong; Dai, Ying; Guo, Meng; Niu, Chengwang; Lu, Jibao; Huang, BaibiaoPhysical Chemistry Chemical Physics (2011), 13 (34), 15546-15553CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)Very recently, two-dimensional nanosheets of MoSe2, MoTe2 and WS2 were successfully synthesized exptl. [Science, 2011, 331, 568]. In the present work, the electronic and magnetic properties of perfect, vacancy-doped, and nonmetal element (H, B, C, N, O, and F) adsorbed MoSe2, MoTe2 and WS2 monolayers are systematically investigated by means of first-principles calcns. to give a detailed understanding of these materials. It is found that: (1) MoSe2, MoTe2 and WS2 exhibit surprising confinement-induced indirect-direct-gap crossover; (2) among all the neutral native vacancies of MoSe2, MoTe2 and WS2 monolayers, only the Mo vacancy in MoSe2 can induce spin-polarization and long-range antiferromagnetic coupling; (3) adsorption of nonmetal elements on the surface of MoSe2, MoTe2 and WS2 nanosheets can induce a local magnetic moment; H-absorbed WS2, MoSe2, and MoTe2 monolayers and F-adsorbed WS2 and MoSe2 monolayers show long-range antiferromagnetic coupling between local moments even when their distance is as long as ∼12 Å. These findings are a useful addn. to the exptl. studies of these new synthesized two-dimensional nanosheets, and suggest a new route to facilitate the design of spintronic devices for complementing graphene. Further exptl. studies are expected to confirm the attractive predictions.
- 103Zhang, Y.; Chang, T. R.; Zhou, B.; Cui, Y. T.; Yan, H.; Liu, Z.; Schmitt, F.; Lee, J.; Moore, R.; Chen, Y. Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2. Nat. Nanotechnol. 2014, 9, 111– 115, DOI: 10.1038/nnano.2013.277Google Scholar103https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhvFOmtr%252FE&md5=5df002c4adb2759963871c0b24f99d69Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2Zhang, Yi; Chang, Tay-Rong; Zhou, Bo; Cui, Yong-Tao; Yan, Hao; Liu, Zhongkai; Schmitt, Felix; Lee, James; Moore, Rob; Chen, Yulin; Lin, Hsin; Jeng, Horng-Tay; Mo, Sung-Kwan; Hussain, Zahid; Bansil, Arun; Shen, Zhi-XunNature Nanotechnology (2014), 9 (2), 111-115CODEN: NNAABX; ISSN:1748-3387. (Nature Publishing Group)Quantum systems in confined geometries are host to novel phys. phenomena. Examples include quantum Hall systems in semiconductors and Dirac electrons in graphene. Interest in such systems was also intensified by the recent discovery of a large enhancement in photoluminescence quantum efficiency and a potential route to valleytronics in atomically thin layers of transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te), which are closely related to the indirect-to-direct bandgap transition in monolayers. Here, we report the 1st direct observation of the transition from indirect to direct bandgap in monolayer samples by angle-resolved photoemission spectroscopy on high-quality thin films of MoSe2 with variable thickness, grown by MBE. The band structure measured exptl. indicates a stronger tendency of monolayer MoSe2 towards a direct bandgap, as well as a larger gap size, than theor. predicted. Moreover, our finding of a significant spin-splitting of ∼180 meV at the valence band max. of a monolayer MoSe2 film could expand its possible application to spintronic devices.
- 104Muehlethaler, C.; Considine, C. R.; Menon, V.; Lin, W. C.; Lee, Y. H.; Lombardi, J. R. Ultrahigh Raman enhancement on monolayer MoS2. ACS Photonics 2016, 3, 1164– 1169, DOI: 10.1021/acsphotonics.6b00213Google Scholar104https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XptlCiu78%253D&md5=f5aa6fea89b66d5ea544e3b965552b98Ultrahigh Raman Enhancement on Monolayer MoS2Muehlethaler, Cyril; Considine, Christopher R.; Menon, Vinod; Lin, Wei-Cheng; Lee, Yi-Hsien; Lombardi, John R.ACS Photonics (2016), 3 (7), 1164-1169CODEN: APCHD5; ISSN:2330-4022. (American Chemical Society)Surface-enhanced Raman scattering (SERS) is commonly assocd. with noble metal substrates. However, over the years modest Raman enhancements (<104) have also been obsd. in semiconductor substrates. This enhancement stems predominantly from the excitonic resonance of the semiconductors. The use of two-dimensional semiconductors with large excitonic oscillator strength provides an attractive pathway to further enhance this effect. Here we report for the first time a >3 × 105 enhancement in SERS signal from an org. mol. (4-mercaptopyridine) placed in the near field of a two-dimensional semiconductor molybdenum disulfide (MoS2) monolayer. This large enhancement in the SERS signal is attributed to the charge transfer (CT) state formed at the interface of the 2D semiconductor and org. mol. and is found to occur when the excitation source is chosen to be in resonance with the CT state. This approach provides a new strategy for carrying out SERS expts. on mols. with very weak Raman signatures without the need for nanopatterning.
- 105Lee, Y.; Kim, H.; Lee, J.; Yu, S. H.; Hwang, E.; Lee, C.; Ahn, J.-H.; Cho, J. H. Enhanced Raman Scattering of Rhodamine 6G Films on Two-Dimensional Transition Metal Dichalcogenides Correlated to Photoinduced Charge Transfer. Chem. Mater. 2016, 28 (1), 180– 187, DOI: 10.1021/acs.chemmater.5b03714Google Scholar105https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFWrtr%252FL&md5=db0491c388b95643afe163629843fe57Enhanced Raman Scattering of Rhodamine 6G Films on Two-Dimensional Transition Metal Dichalcogenides Correlated to Photoinduced Charge TransferLee, Youngbin; Kim, Hyunmin; Lee, Jinhwan; Yu, Seong Hun; Hwang, Euyheon; Lee, Changgu; Ahn, Jong-Hyun; Cho, Jeong HoChemistry of Materials (2016), 28 (1), 180-187CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)The authors studied the surface-enhanced Raman scattering of an org. fluoropore (Rhodamine 6G, R6G) monolayer adsorbed onto graphene and two-dimensional (2D) molybdenum disulfides (MoS2) phototransistors and compared the results with the Raman scattering of R6G on 2-dimensional tungsten diselenides system (WSe2). The Raman enhancement factor of the R6G film adsorbed onto WSe2 was comparable to the corresponding value on graphene at 1365 cm-1 and was approx. twice this value at 615 cm-1. The amplitude of the charge transfer was estd. in situ by measuring the photocurrent produced in a hybrid system consisting of physisorbed R6G layer and the 2-dimensional materials. The enhanced Raman scattering of R6G adsorbed onto the 2-dimensional materials was closely correlated with the charge transfer between the adsorbed mols. and the 2-dimensional materials. The authors also revealed that the intensity of Raman scattering generally decreased as the layer no. of the 2-dimensional materials increased. For the R6G on the MoS2 nanosheet, a single layer system provided a max. Raman enhancement factor, and this value decreased pseudolinearly with the no. of layers. By contrast, the Raman enhancement factor of the R6G on WSe2 was greatest for both the mono- and bilayers, and it decreased dramatically as the no. of layers increased. The authors provide qual. theor. explanations for these trends based on the elec. field enhancement for the multile Fresnel phases and energy band diagrams of both systems.
- 106Meng, L.; Hu, S.; Xu, C.; Wang, X.; Li, H.; Yan, X. Surface enhanced Raman effect on CVD growth of WS2 film. Chem. Phys. Lett. 2018, 707, 71– 74, DOI: 10.1016/j.cplett.2018.07.040Google Scholar106https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtlOrtrnP&md5=c76bf5b02ce09c933054dd419de3cad9Surface enhanced Raman effect on CVD growth of WS2 filmMeng, Lan; Hu, Song; Xu, Chaoji; Wang, Xiangfu; Li, Heng; Yan, XiaohongChemical Physics Letters (2018), 707 (), 71-74CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)Chem. vapor deposition (CVD) method was used to grow large area and layer controllable WS2 film. Our results show that the as grown WS2 film is an excellent substrate for surface enhanced Raman scattering (SERS). The Raman enhancement effect depends crucially on the layer no. of WS2 film: monolayer WS2 offers the strongest Raman signal, and the Raman enhancement effect gradually decreases with the increase in the layer no. of WS2. Further anal. indicates that this transition originates from the charge transfer yield between the R6G mols. and the underlying WS2 substrate.
- 107Zhao, W.; Ghorannevis, Z.; Chu, L.; Toh, M.; Kloc, C.; Tan, P.-H.; Eda, G. Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2. ACS Nano 2013, 7 (1), 791– 797, DOI: 10.1021/nn305275hGoogle Scholar107https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvVGrur%252FM&md5=1077846a4fad1eb6029ced7f87b1a708Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2Zhao, Weijie; Ghorannevis, Zohreh; Chu, Leiqiang; Toh, Minglin; Kloc, Christian; Tan, Ping-Heng; Eda, GokiACS Nano (2013), 7 (1), 791-797CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Geometrical confinement effect in exfoliated sheets of layered materials leads to significant evolution of energy dispersion in mono- to few-layer thickness regime. Molybdenum disulfide (MoS2) was recently found to exhibit indirect-to-direct gap transition when the thickness is reduced to a single monolayer. Emerging photoluminescence (PL) from monolayer MoS2 opens up opportunities for a range of novel optoelectronic applications of the material. Here we report differential reflectance and PL spectra of mono- to few-layer WS2 and WSe2 that indicate that the band structure of these materials undergoes similar indirect-to-direct gap transition when thinned to a single monolayer. The transition is evidenced by distinctly enhanced PL peak centered at 630 and 750 nm in monolayer WS2 and WSe2, resp. Few-layer flakes are found to exhibit comparatively strong indirect gap emission along with direct gap hot electron emission, suggesting high quality of synthetic crystals prepd. by a chem. vapor transport method. Fine absorption and emission features and their thickness dependence suggest a strong effect of Se p-orbitals on the d electron band structure as well as interlayer coupling in WSe2.
- 108(a) Ling, X.; Wu, J.; Xu, W.; Zhang, J. Probing the Effect of Molecular Orientation on the Intensity of Chemical Enhancement Using Graphene Enhanced Raman Spectroscopy. Small 2012, 8 (9), 1365– 1372, DOI: 10.1002/smll.201102223Google ScholarThere is no corresponding record for this reference.(b) Yang, H.; Hu, H.; Ni, Z.; Poh, C. K.; Cong, C.; Lin, J.; Yu, T. Comparison of surface-enhanced Raman scattering on graphene oxide, reduced graphene oxide and graphene surfaces. Carbon 2013, 62, 422– 429, DOI: 10.1016/j.carbon.2013.06.027Google Scholar108bhttps://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXhtVKntL%252FP&md5=9243439a15dbccd426275f97d3f14009Comparison of surface-enhanced Raman scattering on graphene oxide, reduced graphene oxide and graphene surfacesYang, Huanping; Hu, Hailong; Ni, Zhenhua; Poh, Chee Kok; Cong, Chunxiao; Lin, Jianyi; Yu, TingCarbon (2013), 62 (), 422-429CODEN: CRBNAH; ISSN:0008-6223. (Elsevier Ltd.)To explore the role of the interaction between the adsorbed mols. and substrates for the charge transfer (CT) induced Raman enhancement, surface enhanced Raman scattering (SERS) has been studied on graphene, graphene oxide (GO) and reduced graphene oxide (r-GO) using rhodamine 6G (R6G) as the probe mol. The Raman spectra of R6G mols. deposited on these three SERS substrates show remarkable difference in spectral features due to the different enhancement contributions from the local chem. groups and the global π-conjugation network of the substrates. What is more surprising is that for 1-4 layers graphene-based materials, the Raman signals of R6G on GO are found to increase intensity with the no. of GO layers, while the Raman signals of R6G on different graphene/r-GO layers show inverse trends due to dominant π-π stacking mechanism. Our results provide a comprehensive understanding of the influence of local chem. groups and the global π-conjugation network on the SERS enhancements. In addn. to high reproducibility, low cost, and good biocompatibility of GO, the rich chem. structures and the absence of electromagnetic enhancement make it an excellent choice as a tunable substrate to study the chem. enhancement resulting from the adsorbent-substrate interaction.
- 109Etchegoin, P. G.; Lacharmoise, P. D.; Le Ru, E. C. Influence of Photostability on Single-Molecule Surface Enhanced Raman Scattering Enhancement Factors. Anal. Chem. 2009, 81 (2), 682– 688, DOI: 10.1021/ac802083zGoogle Scholar109https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVyhs7vF&md5=2c2b61b2f156ece8f1257aed7dfd5cbbInfluence of Photostability on Single-Molecule Surface Enhanced Raman Scattering Enhancement FactorsEtchegoin, P. G.; Lacharmoise, P. D.; Le Ru, E. C.Analytical Chemistry (Washington, DC, United States) (2009), 81 (2), 682-688CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)Exptl. detns. of enhancement factors in Surface Enhanced Raman Scattering (SERS) are intimately intertwined with the photostability of the probes. The authors study the effect of the limited photostability in single-mol. SERS (SM-SERS) events and show explicitly how this may result in a large under-estn. of the SERS enhancement factors (EFs) obtained exptl. To this end, the authors use the bianalyte technique with isotopically edited probes to provide the best-case scenario for the isolation of single mol. events, and study the statistics of EFs at different incident laser powers. When photobleaching stops playing an important role within the integration time used to capture the spectra, SM-SERS EFs approach an upper bound, which is in agreement with estns. of the EFs within the electromagnetic theory of SERS enhancements. The authors' results reinforce the fact that the highest SM-SERS EFs obsd. exptl. are typically of the order of ∼1010.
- 110Zhao, Y.; Xie, Y.; Bao, Z.; Tsang, Y. H.; Xie, L.; Chai, Y. Enhanced SERS Stability of R6G Molecules with Monolayer Graphene. J. Phys. Chem. C 2014, 118 (22), 11827– 11832, DOI: 10.1021/jp503487aGoogle Scholar110https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXotVeltbg%253D&md5=d2c9533edd161afa943e583dc3f509e5Enhanced SERS Stability of R6G Molecules with Monolayer GrapheneZhao, Yuda; Xie, Yizhu; Bao, Zhiyong; Tsang, Yuen Hong; Xie, Liming; Chai, YangJournal of Physical Chemistry C (2014), 118 (22), 11827-11832CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The authors used monolayer graphene, either underneath or on top of the R6G mols., to enhance the stability and reproducibility of surface enhanced Raman spectroscopy (SERS). The time evolution of characteristic peaks of the org. mols. was monitored using Raman spectroscopy under continuous light irradn. to quant. characterize the photostability. Graphene underneath the org. mols. inhibits the substrate-induced fluctuations; and graphene on top of the org. mols. encapsulates and isolates them from ambient oxygen, greatly enhancing the photostability. The authors' results showed that the av. lifespan of R6G mols. with graphene encapsulation can be increased by ∼6-fold under high laser power d. (3.67 × 106 W/cm2) and is less dependent on the power d. of light irradn.
- 111Weng, J.; Zhao, S.; Li, Z.; Ricardo, K. B.; Zhou, F.; Kim, H.; Liu, H. Raman Enhancement and Photo-Bleaching of Organic Dyes in the Presence of Chemical Vapor Deposition-Grown Graphene. Nanomaterials 2017, 7, 337, DOI: 10.3390/nano7100337Google Scholar111https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhvVGksbrJ&md5=4f7b36ae9910e7c54c6a537688c765cfRaman enhancement and photo-bleaching of organic dyes in the presence of chemical vapor deposition-grown graphemeWeng, Jiaxin; Zhao, Shichao; Li, Zhiting; Ricardo, Karen B.; Zhou, Feng; Kim, Hyojeong; Liu, HaitaoNanomaterials (2017), 7 (10), 337/1-337/12CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)Fluorescent org. dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of org. dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chem. vapor deposition (CVD)-grown graphene. We show that graphene enhances the Raman signal of a wide range of dyes. The photo-bleaching of the dyes was reduced when the dyes were in contact with graphene. In contrast, monolayer hexagonal boron nitride (h-BN) was much less effective in reducing the photo-bleaching rate of the dyes. We attribute the suppression of photo-bleaching to the energy or electron transfer from dye to graphene. The results highlight the potential of CVD graphene as a substrate for protecting and enhancing Raman response of org. dyes.
- 112Qiu, H.; Li, Z.; Gao, S.; Chen, P.; Zhang, C.; Jiang, S.; Xu, S.; Yang, C.; Li, H. Large-area MoS2 thin layers directly synthesized on Pyramid-Si substrate for surface-enhanced Raman scattering. RSC Adv. 2015, 5, 83899– 83905, DOI: 10.1039/C5RA16640CGoogle Scholar112https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsFKku7vF&md5=4b4266fa801a152d2343013dadc97462Large-area MoS2 thin layers directly synthesized on Pyramid-Si substrate for surface-enhanced Raman scatteringQiu, Hengwei; Li, Zhen; Gao, Saisai; Chen, Peixi; Zhang, Chao; Jiang, Shouzhen; Xu, Shicai; Yang, Cheng; Li, HongshengRSC Advances (2015), 5 (102), 83899-83905CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)In our work, we directly synthesized few layer MoS2 on a pyramid-Si substrate to fabricate a surface-enhanced Raman scattering (SERS) substrate via thermally decompg. the precursor of ammonium thiomolybdate ((NH4)2MoS4). SEM (SEM), at. force microscopy (AFM), X-ray diffraction (XRD) and Raman spectra are employed to characterize the as-grown MoS2 layers. Adenosine and cytidine were selected as the probe mols. to investigate the SERS ability of the MoS2-pyramid-Si substrate, and have shown that the MoS2-pyramid-Si substrate can prominently suppress photobleaching and fluorescence of the probe mol. Compared with the MoS2-flat-Si substrate (MoS2 layers synthesized on flat-Si substrate), the MoS2-pyramid-Si substrate has more significant SERS ability. The min. detected concn. of both adenosine and cytidine on the MoS2-pyramid-Si substrate can reach 10-6 M. Importantly, the linear relationship between the Raman intensity and the concn. of adenosine or cytidine can apply to the bimol. detection. This work may provide a new opportunity for the study of the chem. mechanism (CM) and novel SERS substrate fabrication.
- 113Song, X.; Wang, Y.; Zhao, F.; Li, Q.; Ta, H. Q.; Rümmeli, M. H.; Tully, C. G.; Li, Z.; Yin, W.-J.; Yang, L.; Lee, K.-B.; Yang, J.; Bozkurt, I.; Liu, S.; Zhang, W.; Chhowalla, M. Plasmon-Free Surface-Enhanced Raman Spectroscopy Using Metallic 2D Materials. ACS Nano 2019, 13 (7), 8312– 8319, DOI: 10.1021/acsnano.9b03761Google Scholar113https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhtlaru7rP&md5=5cd9bd98884f00410a9b677d3f5558b2Plasmon-Free Surface-Enhanced Raman Spectroscopy Using Metallic 2D MaterialsSong, Xiuju; Wang, Yan; Zhao, Fang; Li, Qiucheng; Ta, Huy Quang; Rummeli, Mark H.; Tully, Christopher G.; Li, Zhenzhu; Yin, Wan-Jian; Yang, Letao; Lee, Ki-Bum; Yang, Jieun; Bozkurt, Ibrahim; Liu, Shengwen; Zhang, Wenjing; Chhowalla, ManishACS Nano (2019), 13 (7), 8312-8319CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Two dimensional (2D) materials-based plasmon-free surface-enhanced Raman scattering (SERS) is an emerging field in nondestructive anal. However, impeded by the low d. of state (DOS), an inferior detection sensitivity is frequently encountered due to the low enhancement factor of most 2D materials. Metallic transition-metal dichalcogenides (TMDs) could be ideal plasmon-free SERS substrates because of their abundant DOS near the Fermi level. However, the absence of controllable synthesis of metallic 2D TMDs has hindered their study as SERS substrates. Here, we realize controllable synthesis of ultrathin metallic 2D niobium disulfide (NbS2) (<2.5 nm) with large domain size (>160μm). We have explored the SERS performance of as-obtained NbS2, which shows a detection limit down to 10-14 mol·L-1. The enhancement mechanism was studied in depth by d. functional theory, which suggested a strong correlation between the SERS performance and DOS near the Fermi level. NbS2 features the most abundant DOS and strongest binding energy with probe mols. as compared with other 2D materials such as graphene, 1T-phase MoS2, and 2H-phase MoS2. The large DOS increases the intermol. charge transfer probability and thus induces prominent Raman enhancement. To extend the results to practical applications, the resulting NbS2-based plasmon-free SERS substrates were applied for distinguishing different types of red wines.
- 114Lei, Z.; Wu, D.; Cao, X.; Zhang, X.; Tao, L.; Zheng, Z.; Feng, X.; Tao, L.; Zhao, Y. 2D platinum telluride as SERS substrate: Unique layer-dependent Raman enhanced effect. J. Alloys Compd. 2023, 937, 168294, DOI: 10.1016/j.jallcom.2022.168294Google Scholar114https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtV2ksrfP&md5=7628c240477513b6e0d1597c3d000a8d2D platinum telluride as SERS substrate: Unique layer-dependent Raman enhanced effectLei, Zehong; Wu, Dongsi; Cao, Xuanhao; Zhang, Xinkuo; Tao, Lili; Zheng, Zhaoqiang; Feng, Xing; Tao, Li; Zhao, YuJournal of Alloys and Compounds (2023), 937 (), 168294CODEN: JALCEU; ISSN:0925-8388. (Elsevier B.V.)Two-dimensional (2D) materials have drawn ever-increasing interest for the application of surface-enhanced Raman scattering (SERS) because of their low-cost synthesis, nontoxic characteristics, flat surface and outstanding optical properties. The unique thickness-dependent SERS of 2D materials is intriguing, but the underlying mechanism of this phenomenon is not fully understood. The few-layer PtTe2, an emerging 2D type-II Dirac semimetal with strong interlayer interaction, is explored as a potential SERS substrate. The Raman enhancement on 2D PtTe2 is confirmed exptl. to be originated from the predominant charge transfer mechanism. The unique thickness-dependent SERS effect reveals that 4-layer (4 L) PtTe2 exhibits the strongest Raman intensity of probe mol. Rhodamine 6 G (R6G). Combined with the theor. study by d. functional theory (DFT), the ultrasensitive SERS effect of 4 L PtTe2 is attributed to its high d. of states (DOS) near the Fermi level and strongest built-in elec. field at the interface of mol./PtTe2. R6G, crystal violet (CV) and rhodamine B (RhB) on 4 L PtTe2 all reach a detection limit ≥10-10 M. The uniformity, stability and photobleaching effect of PtTe2 as SERS substrate is also studied. The charge transfer between mol. and 2D materials is a complex process that is influenced by multiple factors, which might deepen the understanding of the unique chem. mechanism (CM) of SERS in 2D materials.
- 115Fraser, J. P.; Postnikov, P.; Miliutina, E.; Kolska, Z.; Valiev, R.; Švorčík, V.; Lyutakov, O.; Ganin, A. Y.; Guselnikova, O. Application of a 2D Molybdenum Telluride in SERS Detection of Biorelevant Molecules. ACS Appl. Mater. Interfaces 2020, 12, 47774– 47783, DOI: 10.1021/acsami.0c11231Google Scholar115https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvFaqs73N&md5=6a3c4dc76ceb60f17b01ac212141b510Application of a 2D Molybdenum Telluride in SERS Detection of Biorelevant MoleculesFraser, James P.; Postnikov, Pavel; Miliutina, Elena; Kolska, Zdenka; Valiev, Rashid; Svorcik, Vaclav; Lyutakov, Oleksiy; Ganin, Alexey Y.; Guselnikova, OlgaACS Applied Materials & Interfaces (2020), 12 (42), 47774-47783CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Two-dimensional (2D) transition-metal dichalcogenides have become promising candidates for surface-enhanced Raman spectroscopy (SERS), but currently very few examples of detection of relevant mols. are available. Herein, the authors show the detection of the lipophilic disease marker β-sitosterol on few-layered MoTe2 films. The CVD-grown films are capable of nanomolar detection, exceeding the performance of alternative noble-metal surfaces. The enhancement occurs through the chem. enhancement (CE) mechanism via formation of a surface-analyte complex, which leads to an enhancement factor of ≈104, as confirmed by FTIR, UV-visible, and cyclic voltammetry (CV) analyses and d. functional theory (DFT) calcns. Low values of signal deviation over a seven-layered MoTe2 film confirms the homogeneity and reproducibility of the results in comparison to noble-metal substrate analogs. Furthermore, β-sitosterol detection within cell culture media, a minimal loss of signal over 50 days, and the opportunity for sensor regeneration suggest that MoTe2 can become a promising new SERS platform for biosensing.
- 116Miao, P.; Qin, J.-K.; Shen, Y.; Su, H.; Dai, J.; Song, B.; Du, Y.; Sun, M.; Zhang, W.; Wang, H.-L.; Xu, C.-Y.; Xu, P. Unraveling the Raman Enhancement Mechanism on 1T′-Phase ReS2 Nanosheets. Small 2018, 14 (14), 1704079, DOI: 10.1002/smll.201704079Google ScholarThere is no corresponding record for this reference.
- 117Zhang, X.; Zou, J.; Zhang, X.; Wei, A.; luo, N.; Liu, Z.; Xu, J.; Zhao, Y. Controllable growth of 2D ReS2 flakes and their surface Raman enhancement effects. J. Alloys Compd. 2023, 963, 171207, DOI: 10.1016/j.jallcom.2023.171207Google ScholarThere is no corresponding record for this reference.
- 118Wang, L.; Yu, D.; Huang, B.; Ou, Z.; Tao, L.; Tao, L.; Zheng, Z.; Liu, J.; Yang, Y.; Wei, A.; Zhao, Y. Large-area ReS2 monolayer films on flexible substrate for SERS based molecular sensing with strong fluorescence quenching. Appl. Surf. Sci. 2021, 542, 148757, DOI: 10.1016/j.apsusc.2020.148757Google Scholar118https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXkt1SjtQ%253D%253D&md5=2b28251fe387ee27079bf48d739ce640Large-area ReS2 monolayer films on flexible substrate for SERS based molecular sensing with strong fluorescence quenchingWang, Li; Yu, Daqing; Huang, Baoquan; Ou, Ziyuan; Tao, Li; Tao, Lili; Zheng, Zhaoqiang; Liu, Jun; Yang, Yibin; Wei, Aixiang; Zhao, YuApplied Surface Science (2021), 542 (), 148757CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Two-dimensional (2D) transition metal dichalcogenides materials have recently been explored as possible substrates for surface-enhanced Raman spectroscopy (SERS). However, in comparison to the conventional noble-metal-based counterpart, most of the 2D materials have very small area for SERS measurement, which is a big limitation toward practical applications. Herein, we presented our study of SERS using substrate-scale continuous ReS2 monolayer films on flexible mica substrate. We demonstrated that the charge transfer between the target mols. and the atomically thin ReS2 can be modulated by the underlying substrate of ReS2, resulting in greatly different suppressing level of FL background. Kelvin probe force microscopy revealed a large difference of surface potential between ReS2/SiO2 and ReS2/mica, suggesting that the strong FL quenching of mol. on ReS2/mica might be attributed to the inert surface of layered mica. The large-area ReS2 monolayer films on mica show a detection limit of R6G mol. around 10-7 M and a robust SERS performance after an exposure in air for one month and repeated bending for 1000 times. Our work explores the practical application of 2D ReS2 for mol. detection via SERS technique.
- 119Tao, L.; Chen, K.; Chen, Z.; Cong, C.; Qiu, C.; Chen, J.; Wang, X.; Chen, H.; Yu, T.; Xie, W.; Deng, S.; Xu, J.-B. 1T′ Transition Metal Telluride Atomic Layers for Plasmon-Free SERS at Femtomolar Levels. J. Am. Chem. Soc. 2018, 140 (28), 8696– 8704, DOI: 10.1021/jacs.8b02972Google Scholar119https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtFyjs7bN&md5=471eeea1cf9505adc7e83a66a6963aef1T' Transition Metal Telluride Atomic Layers for Plasmon-Free SERS at Femtomolar LevelsTao, Li; Chen, Kun; Chen, Zefeng; Cong, Chunxiao; Qiu, Caiyu; Chen, Jiajie; Wang, Ximiao; Chen, Huanjun; Yu, Ting; Xie, Weiguang; Deng, Shaozhi; Xu, Jian-BinJournal of the American Chemical Society (2018), 140 (28), 8696-8704CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)Plasmon-free surface enhanced Raman scattering (SERS) based on the chem. mechanism (CM) is drawing great attention due to its capability for controllable mol. detection. However, in comparison to the conventional noble-metal-based SERS technique driven by plasmonic electromagnetic mechanism (EM), the low sensitivity in the CM-based SERS is the dominant barrier toward its practical applications. Herein, the authors demonstrate the 1T' transition metal telluride at. layers (WTe2 and MoTe2) as ultrasensitive platforms for CM-based SERS. The SERS sensitivities of analyte dyes on 1T'-W(Mo)Te2 reach EM-comparable ones and become even greater when it is integrated with a Bragg reflector. The dye fluorescence signals are efficiently quenched, making the SERS spectra more distinguishable. As a proof of concept, the SERS signals of analyte Rhodamine 6G (R6G) are detectable even with an ultralow concn. of 40(400) fM on pristine 1T'-W(Mo)Te2, and the corresponding Raman enhancement factor (EF) reaches 1.8 × 109 (1.6 × 108). The limit concn. of detection and the EF of R6G can be further enhanced into 4(40) fM and 4.4 × 1010 (6.2 × 109), resp., when 1T'-W(Mo)Te2 is integrated on the Bragg reflector. The strong interaction between the analyte and 1T'-W(Mo)Te2 and the abundant d. of states near the Fermi level of the semimetal 1T'-W(Mo)Te2 in combination gives rise to the promising SERS effects by promoting the charge transfer resonance in the analyte-telluride complex.
- 120Su, S.; Zhang, C.; Yuwen, L.; Chao, J.; Zuo, X.; Liu, X.; Song, C.; Fan, C.; Wang, L. Creating SERS hot spots on MoS2 nanosheets with in situ grown gold nanoparticles. ACS Appl. Mater. Interfaces 2014, 6, 18735– 18741, DOI: 10.1021/am5043092Google Scholar120https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhslCjtbbF&md5=6f34c4cffa3b47fb1516daa82f9bd5faCreating SERS Hot Spots on MoS2 Nanosheets with in Situ Grown Gold NanoparticlesSu, Shao; Zhang, Chi; Yuwen, Lihui; Chao, Jie; Zuo, Xiaolei; Liu, Xingfen; Song, Chunyuan; Fan, Chunhai; Wang, LianhuiACS Applied Materials & Interfaces (2014), 6 (21), 18735-18741CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Herein, a reliable surface-enhanced Raman scattering (SERS)-active substrate was prepd. by synthesizing Au nanoparticles (AuNPs)-decorated MoS2 nanocomposite. The AuNPs grew in situ on the surface of MoS2 nanosheet to form efficient SERS hot spots by a spontaneous redox reaction with tetrachloroauric acid (HAuCl4) without any reducing agent. The morphologies of MoS2 and AuNPs-decorated MoS2 nanosheet were characterized by TEM, HRTEM, and AFM. The formation of hot spots greatly depended on the ratio of MoS2 and HAuCl4. When the concn. of HAuCl4 was 2.4 mM, the as-prepd. AuNPs@MoS2-3 nanocomposite exhibited a high-quality SERS activity toward probe mol. due to the generated hot spots. The spot-to-spot SERS signals showed that the relative std. deviation in the intensity of the main Raman vibration modes (1362, 1511, and 1652 cm-1) of Rhodamine 6G were ∼20%, which displayed good uniformity and reproducibility. The AuNPs@MoS2-based substrate was reliable, sensitive, and reproducible, which showed great potential to be an excellent SERS substrate for biol. and chem. detection.
- 121Daeneke, T.; Carey, B. J.; Chrimes, A. F.; Ou, J. Z.; Lau, D. W. M.; Gibson, B. C.; Bhaskaran, M.; Kalantar-zadeh, K. Light driven growth of silver nanoplatelets on 2D MoS2 nanosheet templates. J. Mater. Chem. C 2015, 3, 4771– 4778, DOI: 10.1039/C5TC00288EGoogle Scholar121https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXmtlOnsrc%253D&md5=da3dac4276deb787894dfc8e827e7c9bLight driven growth of silver nanoplatelets on 2D MoS2 nanosheet templatesDaeneke, T.; Carey, B. J.; Chrimes, A. F.; Ou, J. Zhen; Lau, D. W. M.; Gibson, B. C.; Bhaskaran, M.; Kalantar-zadeh, K.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2015), 3 (18), 4771-4778CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)A novel synthesis approach for the fabrication of silver nanoparticles and platelets using MoS2 nanosheets has been investigated herein, which is based on the direct photo excitation of the semiconductor bandgap in the presence of silver ions. The silver ions were effectively reduced to silver metal and a range of silver-MoS2 heterostructures were synthesized, depending on illumination time. Short light exposure led to the formation of silver nanoparticles on the MoS2 sheets. Longer illumination time led to a templated growth mechanism and the formation of large silver nanoplatelets, fully encapsulating the MoS2 templates. These silver nanoplatelets were found to self-assemble into large micrometre sized silver nanodendrites/nanobranches which were effectively used as a surface enhanced Raman spectroscopy platform.
- 122Zuo, P.; Jiang, L.; Li, X.; Li, B.; Ran, P.; Li, X.; Qu, L.; Lu, Y. Metal (Ag, Pt)–MoS2 Hybrids Greenly Prepared Through Photochemical Reduction of Femtosecond Laser Pulses for SERS and HER. ACS Sustainable Chem. Eng. 2018, 6 (6), 7704– 7714, DOI: 10.1021/acssuschemeng.8b00579Google ScholarThere is no corresponding record for this reference.
- 123Lu, J. P.; Lu, J. H.; Liu, H. W.; Liu, B.; Gong, L.; Tok, E. S.; Loh, K. P.; Sow, C. H. Microlandscaping of Au nanoparticles on few-layer MoS2 films for chemical sensing. Small 2015, 11, 1792– 1800, DOI: 10.1002/smll.201402591Google Scholar123https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXosFelsQ%253D%253D&md5=dd4af950ad77b391b18f52981b46844bMicrolandscaping of Au Nanoparticles on Few-Layer MoS2 Films for Chemical SensingLu, Junpeng; Lu, Jia Hui; Liu, Hongwei; Liu, Bo; Gong, Lili; Tok, Eng Soon; Loh, Kian Ping; Sow, Chorng HaurSmall (2015), 11 (15), 1792-1800CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Surface modification or decoration of ultrathin MoS2 films with chem. moieties is appealing since nanointerfacing can functionalize MoS2 films with bonus potentials. A facile and effective method for microlandscaping of Au nanoparticles (NPs) on few-layer MoS2 films is developed. This approach 1st employs a focused laser beam to premodify the MoS2 films to achieve active surface domains with unbound sulfur. When the activated surface is subsequently immersed in AuCl3 soln., Au NPs preferentially decorate onto the modified regions. As a result, Au NPs can be selectively and locally anchored onto designated regions on the MoS2 surface. With a scanning laser beam, microlandscapes comprising of Au NPs decorated on laser-defined micropatterns are constructed. By varying the laser power, reaction time and thickness of the MoS2 films, the size and d. of the NPs can be controlled. The resulting hybrid materials are demonstrated as efficient Raman active surfaces for the detection of arom. mols. with high sensitivity.
- 124Zuo, P.; Jiang, L.; Li, X.; Li, B.; Xu, Y.; Shi, X.; Ran, P.; Ma, T.; Li, D.; Qu, L.; Lu, Y. Shape-Controllable Gold Nanoparticle–MoS2 Hybrids Prepared by Tuning Edge-Active Sites and Surface Structures of MoS2 via Temporally Shaped Femtosecond Pulses. ACS Appl. Mater. Interfaces 2017, 9 (8), 7447– 7455, DOI: 10.1021/acsami.6b14805Google ScholarThere is no corresponding record for this reference.
- 125Zhou, L.; Zhang, H.; Bao, H.; Liu, G.; Li, Y.; Cai, W. Decoration of Au Nanoparticles on MoS2 Nanospheres: From Janus to Core/Shell Structure. J. Phys. Chem. C 2018, 122 (15), 8628– 8636, DOI: 10.1021/acs.jpcc.8b01216Google ScholarThere is no corresponding record for this reference.
- 126Kaushik, A.; Singh, J.; Soni, R.; Singh, J. P. MoS2–Ag Nanocomposite-Based SERS Substrates with an Ultralow Detection Limit. ACS Appl. Nano Mater. 2023, 6 (11), 9236– 9246, DOI: 10.1021/acsanm.3c00813Google ScholarThere is no corresponding record for this reference.
- 127Ghopry, S. A.; Sadeghi, S. M.; Berrie, C. L.; Wu, J. Z. MoS2 Nanodonuts for High-Sensitivity Surface-Enhanced Raman Spectroscopy. Biosensors 2021, 11, 477, DOI: 10.3390/bios11120477Google ScholarThere is no corresponding record for this reference.
- 128Sow, B. M.; Lu, J.; Liu, H.; Goh, K. E. J.; Sow, C. H. Sow, Enriched fluorescence emission from WS2 monoflake empowered by Au nanoexplorers. Adv. Optical Mater. 2017, 5, 1700156, DOI: 10.1002/adom.201700156Google ScholarThere is no corresponding record for this reference.
- 129Mukherjee, B.; Sun Leong, W.; Li, Y.; Gong, H.; Sun, L.; Xiang Shen, Z.; Simsek, E.; Thong, J. T. L. Raman analysis of gold on WSe2 single crystal film. Mater. Res. Exp. 2015, 2 (6), 065009, DOI: 10.1088/2053-1591/2/6/065009Google ScholarThere is no corresponding record for this reference.
- 130Abid, I.; Chen, W.; Yuan, J.; Najmaei, S.; Peñafiel, E. C.; Péchou, R.; Large, N.; Lou, J.; Mlayah, A. Surface enhanced resonant Raman scattering in hybrid MoSe2@Au nanostructures. Opt. Express 2018, 26 (22), 29411– 29423, DOI: 10.1364/OE.26.029411Google Scholar130https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXnt1KrsLo%253D&md5=e2613fd8d03cc9130d6f1f3219387789Surface enhanced resonant Raman scattering in hybrid MoSe2@Au nanostructuresAbid, Ines; Chen, Weibing; Yuan, Jiangtan; Najmaei, Sina; Penafiel, Emil C.; Pechou, Renaud; Large, Nicolas; Lou, Jun; Mlayah, AdnenOptics Express (2018), 26 (22), 29411-29423CODEN: OPEXFF; ISSN:1094-4087. (Optical Society of America)We report on the surface enhanced resonant Raman scattering (SERRS) in hybrid MoSe2@Au plasmonic-excitonic nanostructures, focusing on the situation where the localized surface plasmon resonance of Au nanodisks is finely tuned to the exciton absorption of monolayer MoSe2. Using a resonant excitation, we investigate the SERRS in MoSe2@Au and the resonant Raman scattering (RRS) in a MoSe2@SiO2 ref. Both optical responses are compared to the non-resonant Raman scattering signal, thus providing an est. of the relative contributions from the localized surface plasmons and the confined excitons to the Raman scattering enhancement. We det. a SERRS/RRS enhancement factor exceeding one order of magnitude. Furthermore, using numerical simulations, we explore the optical near-field properties of the hybrid MoSe2@Au nanostructure and investigate the SERRS efficiency dependence on the nanodisk surface morphol. and on the excitation wavelength. We demonstrate that a photothermal effect, due to the resonant plasmonic pumping of electron-hole pairs into the MoSe2 layer, and the surface roughness of the metallic nanostructures are the main limiting factors of the SERRS efficiency.
- 131Li, Y.; Liao, H.; Wu, S.; Weng, X.; Wang, Y.; Liu, L.; Qu, J.; Song, J.; Ye, S.; Yu, X.; Chen, Y. ReS2 Nanoflowers-Assisted Confined Growth of Gold Nanoparticles for Ultrasensitive and Reliable SERS Sensing. Molecules 2023, 28 (11), 4288, DOI: 10.3390/molecules28114288Google ScholarThere is no corresponding record for this reference.
- 132Jung, H. S.; Koh, E. H.; Mun, C.; Min, J.; Sohng, W.; Chung, H.; Yang, J.-Y.; Lee, S.; Kim, H. J.; Park, S.-G.; Lee, M.-Y.; Kim, D.-H. Hydrophobic hBN-coated surface-enhanced Raman scattering sponge sensor for simultaneous separation and detection of organic pollutants. J. Mater. Chem. C 2019, 7, 13059– 13069, DOI: 10.1039/C9TC04299GGoogle Scholar132https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhvVWitLrI&md5=d4e6beafdd22b2af7bde5ae31691e1ddHydrophobic hBN-coated surface-enhanced Raman scattering sponge sensor for simultaneous separation and detection of organic pollutantsJung, Ho Sang; Koh, Eun Hye; Mun, ChaeWon; Min, Jeongho; Sohng, Woosuk; Chung, Hoeil; Yang, Jun-Yeong; Lee, Seunghun; Kim, Hyo Jung; Park, Sung-Gyu; Lee, Min-Young; Kim, Dong-HoJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (42), 13059-13069CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)Z sponge-based, surface-enhanced Raman scattering (SERS) sensor comprised of Ag nanowires (AgNW) coated with hydrophobic hexagonal boron nitride (hBN) was prepd. to simultaneously sep. and detect org. pollutants. AgNW adhered on a melamine-sponge surface formed a high d. of hotspots for Raman signal enhancement; the hydrophobic hBN-coated AgNW functioned as an absorbent to sep. org. pollutants from water by hydrophobic and π-π interactions. Due to Raman spectroscopy advantages, which provide an intrinsic mol. Raman signal, typical org. pollutants (benzene, toluene, ethylbenzene, xylene [BTEX]) were identified by a portable Raman spectrometer using a label-free method following sepn. using the developed sensor. Binary and ternary BTEX mixts. were also recognized by comparing the Raman spectrum of each component in the mixts., followed by easy classified by principal component anal. Absorbent capacity, reusability tests, and application to environmental water using the developed hBN/AgNW/sponge samples showed excellent org. pollutant sepn. properties as a hydrophobic sponge and cost effective utilization of the developed sensor for mol. detection. The hBN/AgNW/sponge sensor is expected to be applicable for on-site, label-free org. compd. sepn. and identification, e.g., environmental and biomedical monitoring.
- 133Jiang, S.; Guo, J.; Zhang, C.; Li, C.; Wang, M.; Li, Z.; Gao, S.; Chen, P.; Si, H.; Xu, S. A sensitive, uniform, reproducible and stable SERS substrate has been presented based on MoS2@Ag nanoparticles@pyramidal silicon. RSC Adv. 2017, 7, 5764– 5773, DOI: 10.1039/C6RA26879JGoogle Scholar133https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtFeitrk%253D&md5=64c2697df6df8f80a26dde0f6002da6cA sensitive, uniform, reproducible and stable SERS substrate has been presented based on MoS2@Ag nanoparticles@pyramidal siliconJiang, Shouzhen; Guo, Jia; Zhang, Chao; Li, Chonghui; Wang, Minghong; Li, Zhen; Gao, Saisai; Chen, Peixi; Si, Haipeng; Xu, ShicaiRSC Advances (2017), 7 (10), 5764-5773CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)By combining the excellent surface-enhanced Raman scattering (SERS) activity of Ag nanoparticles (AgNPs), the well-sepd. pyramid arrays of the pyramidal silicon (PSi) and unique phys./chem. properties of molybdenum disulfide (MoS2), the MoS2@AgNPs@PSi substrate shows high performance in terms of sensitivity, uniformity, reproducibility and stability. By using rhodamine 6G (R6G) as probe mol., the SERS results indicate that the MoS2@AgNPs@PSi substrate is superior to the AgNPs@PSi, AgA@PSi (the second annealing of the AgNPs@PSi) and the MoS2@AgNPs@flat-Si substrate. The MoS2@AgNPs@PSi substrate also shows the reasonable linear response between the Raman intensity and R6G concn. The max. deviations of SERS intensities from 20 positions on a same MoS2@AgNPs@PSi substrate and 10 MoS2@AgNPs@PSi substrates in different batches are less than 7.6% and 9%, resp., revealing the excellent uniformity and reproducibility of the substrate. Besides, the SERS substrate has a good stability, the Raman intensity of the MoS2@AgNPs@PSi substrate only drop by 15% in a month. The corresponding exptl. and theor. results suggest that our proposed MoS2@AgNPs@PSi substrate is expected to offer a new and practical way to accelerate the development of label-free SERS detection.
- 134Tegegne, W. A.; Su, W.-N.; Tsai, M.-C.; Beyene, A. B.; Hwang, B.-J. Ag nanocubes decorated 1T-MoS2 nanosheets SERS substrate for reliable and ultrasensitive detection of pesticides. Appl. Mater. Today 2020, 21, 100871, DOI: 10.1016/j.apmt.2020.100871Google ScholarThere is no corresponding record for this reference.
- 135O’Hern, S. C.; Boutilier, M. S. H.; Idrobo, J. C.; Song, Y.; Kong, J.; Laoui, T.; Atieh, M.; Karnik, R. Selective ionic transport through tunable subnanometer pores in single-layer graphene membranes. Nano Lett. 2014, 14, 1234– 1241, DOI: 10.1021/nl404118fGoogle Scholar135https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhslSit7w%253D&md5=01af01794292346ed285cc021318d178Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene MembranesO'Hern, Sean C.; Boutilier, Michael S. H.; Idrobo, Juan-Carlos; Song, Yi; Kong, Jing; Laoui, Tahar; Atieh, Muataz; Karnik, RohitNano Letters (2014), 14 (3), 1234-1241CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Selective ionic transport through controlled, high-d., subnanometer diam. pores in macroscopic single-layer graphene membranes has been achieved. Isolated, reactive defects were first introduced into the graphene lattice through ion bombardment and subsequently enlarged by oxidative etching into permeable pores with diams. of 0.40 ± 0.24 nm and densities exceeding 1012 cm-2, while retaining structural integrity of the graphene. Transport measurements across ion-irradiated graphene membranes subjected to in situ etching revealed that the created pores were cation-selective at short oxidn. times, consistent with electrostatic repulsion from neg. charged functional groups terminating the pore edges. At longer oxidn. times, the pores allowed transport of salt but prevented the transport of a larger org. mol., indicative of steric size exclusion. The ability to tune the selectivity of graphene through controlled generation of subnanometer pores addresses a significant challenge in the development of advanced nanoporous graphene membranes for nanofiltration, desalination, gas sepn., and other applications.
- 136Suzuki, S.; Yoshimura, M. Chemical Stability of Graphene Coated Silver Substrates for Surface-Enhanced Raman Scattering. Sci. Rep. 2017, 7, 14851, DOI: 10.1038/s41598-017-14782-2Google Scholar136https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1M7mvVSmsA%253D%253D&md5=c96d515235faafea151b861c01985712Chemical Stability of Graphene Coated Silver Substrates for Surface-Enhanced Raman ScatteringSuzuki Seiya; Yoshimura MasamichiScientific reports (2017), 7 (1), 14851 ISSN:.Surface enhanced Raman spectroscopy (SERS) is a novel method to sense molecular and lattice vibrations at a high sensitivity. Although nanostructured silver surface provides intense SERS signals, the silver surface is unstable under acidic environment and heated environment. Graphene, a single atomic carbon layer, has a prominent stability for chemical agents, and its honeycomb lattice completely prevents the penetration of small molecules. Here, we fabricated a SERS substrate by combining nanostructured silver surface and single-crystal monolayer graphene (G-SERS), and focused on its chemical stability. The G-SERS substrate showed SERS even in concentrated hydrochloric acid (35-37%) and heated air up to 400 °C, which is hardly obtainable by normal silver SERS substrates. The chemically stable G-SERS substrate posesses a practical and feasible application, and its high chemical stability provides a new type of SERS technique such as molecular detections at high temperatures or in extreme acidic conditions.
- 137Chen, P. X.; Qiu, H. W.; Xu, S. C.; Liu, X. Y.; Li, Z.; Hu, L. T.; Li, C. H.; Guo, J.; Jiang, S. Z.; Huo, Y. Y. A novel surface-enhanced Raman spectroscopy substrate based on a large area of MoS2 and Ag nanoparticles hybrid system. Appl. Surf. Sci. 2016, 375, 207– 214, DOI: 10.1016/j.apsusc.2016.03.053Google Scholar137https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XjvVyqur4%253D&md5=952c0b4b43354528afb9ae8996c5fa1bA novel surface-enhanced Raman spectroscopy substrate based on a large area of MoS2 and Ag nanoparticles hybrid systemChen, P. X.; Qiu, H. W.; Xu, S. C.; Liu, X. Y.; Li, Z.; Hu, L. T.; Li, C. H.; Guo, J.; Jiang, S. Z.; Huo, Y. Y.Applied Surface Science (2016), 375 (), 207-214CODEN: ASUSEE; ISSN:0169-4332. (Elsevier B.V.)Few layers MoS2 were directly synthesized on Ag nanoparticles (AgNPs) by thermal decompn. method to fabricate a MoS2/AgNPs hybrid system for surface-enhanced Raman scattering (SERS). The MoS2/AgNPs hybrid system shows high performance in terms of sensitivity, signal-to-noise ratio, reproducibility and stability. The min. detected concn. from MoS2/AgNPs hybrid system for R6G can reach 10-9 M, which is one order of magnitude lower than that from AgNPs system. The hybrid system shows the reasonable linear response between the Raman intensity and concn. that R2 is reached to 0.988. The max. deviations of SERS intensities from 20 positions of the SERS substrate are less than 13%. Besides, the hybrid system has a good stability, the Raman intensity only drop by 20% in a month. This work can provide a basis for the fabrication of novel SERS substrates.
- 138Zheng, Z.; Cong, S.; Gong, W.; Xuan, J.; Li, G.; Lu, W.; Geng, F.; Zhao, Z. Semiconductor SERS enhancement enabled by oxygen incorporation. Nat. Commun. 2017, 8, 1993, DOI: 10.1038/s41467-017-02166-zGoogle Scholar138https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1M3ps1OhtQ%253D%253D&md5=7d9c196712d28413a3040c956a7a6487Semiconductor SERS enhancement enabled by oxygen incorporationZheng Zuhui; Cong Shan; Gong Wenbin; Lu Weibang; Zhao Zhigang; Zheng Zuhui; Xuan Jinnan; Li Guohui; Geng FengxiaNature communications (2017), 8 (1), 1993 ISSN:.Semiconductor-based surface-enhanced Raman spectroscopy (SERS) substrates represent a new frontier in the field of SERS. However, the application of semiconductor materials as SERS substrates is still seriously impeded by their low SERS enhancement and inferior detection sensitivity, especially for non-metal-oxide semiconductor materials. Herein, we demonstrate a general oxygen incorporation-assisted strategy to magnify the semiconductor substrate-analyte molecule interaction, leading to significant increase in SERS enhancement for non-metal-oxide semiconductor materials. Oxygen incorporation in MoS2 even with trace concentrations can not only increase enhancement factors by up to 100,000-fold compared with oxygen-unincorporated samples but also endow MoS2 with low limit of detection below 10(-7) M. Intriguingly, combined with the findings in previous studies, our present results indicate that both oxygen incorporation and extraction processes can result in SERS enhancement, probably due to the enhanced charge-transfer resonance as well as exciton resonance arising from the judicious control of oxygen admission in semiconductor substrate.
- 139Zuo, P.; Jiang, L.; Li, X.; Ran, P.; Li, B.; Song, A.; Tian, M.; Ma, T.; Guo, B.; Qu, L.; Lu, Y. Enhancing charge transfer with foreign molecules through femtosecond laser induced MoS2 defect sites for photoluminescence control and SERS enhancement. Nanoscale 2019, 11, 485– 494, DOI: 10.1039/C8NR08785GGoogle Scholar139https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXit1ymt7jM&md5=2f3a47d5d655622b1997cedfb30412c7Enhancing charge transfer with foreign molecules through femtosecond laser induced MoS2 defect sites for photoluminescence control and SERS enhancementZuo, Pei; Jiang, Lan; Li, Xin; Ran, Peng; Li, Bo; Song, Aisheng; Tian, Mengyao; Ma, Tianbao; Guo, Baoshan; Qu, Liangti; Lu, YongfengNanoscale (2019), 11 (2), 485-494CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Defect/active site control is crucial for tuning the chem., optical, and electronic properties of MoS2, which can adjust the performance of MoS2 in application areas such as electronics, optics, catalysis, and mol. sensing. This study presents an effective method of inducing defect/active sites, including micro/nanofractured structures and S at. vacancies, on monolayer MoS2 flakes by using femtosecond laser pulses, through which phys.-chem. adsorption and charge transfer between foreign mols. (O2 or R6G mols.) and MoS2 are enhanced. The enhanced charge transfer between foreign mols. (O2 or R6G) and femtosecond laser-treated MoS2 can enhance the electronic doping effect between them, hence resulting in a photoluminescence photon energy shift (reaching 0.05 eV) of MoS2 and Raman enhancement (reaching 6.4 times) on MoS2 flakes for R6G mol. detection. Finally, photoluminescence control and micropatterns on MoS2 and surface-enhanced-Raman-scattering (SERS) enhancement of MoS2 for org. mol. detection are achieved. The proposed method, which can control the photoluminescence properties and arbitrary micropatterns on MoS2 and enhance its chemicobiol. sensing performance for org./biol. mols., has advantages of simplicity, maskless processing, strong controllability, high precision, and high flexibility, highlighting the superior ability of femtosecond laser pulses to achieve the property control and functionalization of two-dimensional materials.
- 140Quan, Y.; Tang, X.-H.; Shen, W.; Li, P.; Yang, M.; Huang, X.-J.; Liu, W.-Q. Sulfur Vacancies-Triggered High SERS Activity of Molybdenum Disulfide for Ultrasensitive Detection of Trace Diclofenac. Adv. Opt. Mater. 2022, 10 (23), 2201395, DOI: 10.1002/adom.202201395Google ScholarThere is no corresponding record for this reference.
- 141Jena, T.; Hossain, M. T.; Nath, U.; Sarma, M.; Sugimoto, H.; Fujii, M.; Giri, P. K. Evidence for intrinsic defects and nanopores as hotspots in 2D PdSe2 dendrites for plasmon-free SERS substrate with a high enhancement factor. npj 2D Mater. Appl. 2023, 7, 8, DOI: 10.1038/s41699-023-00367-3Google ScholarThere is no corresponding record for this reference.
- 142Su, R.; Yang, S.; Han, D.; Hu, M.; Liu, Y.; Yang, J.; Gao, M. Ni and O co-modified MoS2 as universal SERS substrate for the detection of different kinds of substances. J. Colloid Interface Sci. 2023, 635, 1– 11, DOI: 10.1016/j.jcis.2022.12.075Google Scholar142https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjtF2nsL%252FK&md5=523884fdac33e1739b3086a4e1b2e716Ni and O co-modified MoS2 as universal SERS substrate for the detection of different kinds of substancesSu, Rui; Yang, Shuo; Han, Donglai; Hu, Mingyue; Liu, Yang; Yang, Jinghai; Gao, MingJournal of Colloid and Interface Science (2023), 635 (), 1-11CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Surface-enhanced Raman scattering (SERS) has attracted extensive attention as an ultrasensitive detection method. However, the poor biocompatibility and expensive synthesis cost of noble metal SERS substrates have become non-negligible factors that limit the development of SERS technol. Metal chalcogenide semiconductors as an alternative to noble metal SERS substrates can avoid these disadvantages, but the enhancement effect is lower than that of noble metal substrates. Here, we report a method to co-modify MoS2 by Ni and O, which improves the carrier concn. and mobility of MoS2. The SERS effect of the modified MoS2 is comparable to that of noble metals. We found that the improved SERS performance of MoS2 can be attributed to the following two factors: strong interfacial dipole-dipole interaction and efficient charge transfer effect. During the doping process, the incorporation of Ni and O enhances the polarity and carrier concn. of MoS2, enhances the interfacial interaction of MoS2, and provides a basis for charge transfer. During the annealing process, the introduction of O atoms into the S defects reduces the internal defects of doped MoS2, improves the carrier mobility, and promotes the efficient charge transfer effect of MoS2. The final modified MoS2 as a SERS substrate realizes low-concn. detection of bilirubin, cytochrome C, and trichlorfon. This provides promising guidance for the practical inspection of metal chalcogenide semiconductor substrates.
- 143Jiang, L.; Xiong, S.; Yang, S.; Han, D.; Liu, Y.; Yang, J.; Gao, M. Neodymium doping MoS2 nanostructures with remarkable surface-enhanced Raman scattering activity. Ceram. Int. 2023, 49 (11), 19328– 19337, DOI: 10.1016/j.ceramint.2023.03.060Google ScholarThere is no corresponding record for this reference.
- 144Koklioti, M. A.; Bittencourt, C.; Noirfalise, X.; Saucedo-Orozco, I.; Quintana, M.; Tagmatarchis, N. Nitrogen-Doped Silver-Nanoparticle-Decorated Transition-Metal Dichalcogenides as Surface-Enhanced Raman Scattering Substrates for Sensing Polycyclic Aromatic Hydrocarbons. ACS Appl. Nano Mater. 2018, 1 (7), 3625– 3635, DOI: 10.1021/acsanm.8b00747Google Scholar144https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhtFyqtbfO&md5=39b78176bc7213d112cd8c575da4b28bNitrogen-Doped Silver-Nanoparticle-Decorated Transition-Metal Dichalcogenides as Surface-Enhanced Raman Scattering Substrates for Sensing Polycyclic Aromatic HydrocarbonsKoklioti, Malamatenia A.; Bittencourt, Carla; Noirfalise, Xavier; Saucedo-Orozco, Izcoatl; Quintana, Mildred; Tagmatarchis, NikosACS Applied Nano Materials (2018), 1 (7), 3625-3635CODEN: AANMF6; ISSN:2574-0970. (American Chemical Society)The modification of transition-metal dichalcogenides (TMDs), incorporating nitrogen (N) doping and silver nanoparticles (AgNPs) decoration on the skeleton of exfoliated MoS2 and WS2, was accomplished. The prepn. of N-doped and AgNPs-decorated TMDs involved a one-pot treatment procedure in a vacuum-sputtering chamber under N plasma conditions and in the presence of a silver (Ag) cathode as the source. Two different deposition times, 5 and 10 s, resp., were applied to obtain N-doped with AgNPs-decorated MoS2 and WS2 hybrids, abbreviated as N5-MoS2/AgNPs, N10-MoS2/AgNPs, N5-WS2/AgNPs, and N10-WS2/AgNPs, resp., for each functionalization time. The successful incorporation of N as the dopant within the lattice of exfoliated MoS2 and WS2 as well as the deposition of AgNPs on their surface, yielding N-MoS2/AgNPs and N-WS2/AgNPs, was manifested through extensive XPS measurements. The observation of peaks at ∼398 eV derived from covalently bonded N and the evolution of a doublet of peaks at ∼370 eV guaranteed the presence of AgNPs in the modified TMDs. Also, the morphologies of N-MoS2/AgNPs and N-WS2/AgNPs were examd. by transmission electron microscopy, which proved that Ag deposition resulted in nanoparticle growth rather than the creation of a continuous metal film on the TMD sheets. Next, the newly developed hybrid materials were proven to be efficient surface-enhanced Raman scattering (SERS) platforms by achieving the detection of Rhodamine B (RhB). Markedly, N10-MoS2/AgNPs showed the highest sensitivity for detecting RhB at concns. as low as 10-9 M. Charge-transfer interactions between RhB and the modified TMDs, together with the polarized character of the system causing dipole-dipole coupling interactions, were detd. as the main mechanisms to induce the Raman scattering enhancement. Finally, polycyclic arom. hydrocarbons such as pyrene, anthracene, and 2,3-dihydroxynaphthalene, coordinated via π-S interactions with N-MoS2/AgNPs, were screened with high sensitivity and reproducibility. These findings highlight the excellent functionality of the newly developed N-MoS2/AgNPs and N-WS2/AgNPs hybrid materials as SERS substrates for sensing widespread org. and environmental pollutants as well as carcinogen and mutagen species.
- 145Tian, Y.; Wei, H.; Xu, Y.; Sun, Q.; Man, B.; Liu, M. Influence of SERS Activity of SnSe2 Nanosheets Doped with Sulfur. Nanomaterials 2020, 10, 1910, DOI: 10.3390/nano10101910Google Scholar145https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisVWgtrvN&md5=0fdd546670c9f02f9381ede4d6da450bInfluence of SERS activity of SnSe2 nanosheets doped with sulfurTian, Yuan; Wei, Haonan; Xu, Yujie; Sun, Qianqian; Man, Baoyuan; Liu, MeiNanomaterials (2020), 10 (10), 1910CODEN: NANOKO; ISSN:2079-4991. (MDPI AG)The application of 2D semiconductor nanomaterials in the field of SERS is limited due to its weak enhancement effect and the unclear enhancement mechanism. In this study, we changed the surface morphol. and energy level structure of 2D SnSe2 nanosheets using different amts. of S dopant. This caused the vibration coupling of the substrate and the adsorbed mols. and affects the SERS activities of the SnSe2 nanosheets. SERS performance of the 2D semiconductor substrate can effectively be improved by suitable doping, which can effectively break the limitation of 2D semiconductor compds. in SERS detection and will have very important significance in the fields of chem., biol., and materials sciences. In this work, the intensities of SERS signals for R6G mols. on SnSe0.93S0.94 are 1.3 to 1.7 times stronger than those on pure SnSe2 substrate. It not only provides a new way to effectively improve the SERS activity of a semiconductor SERS substrates but also helps to design more efficient and stable semiconductor SERS substrates for practical application.
- 146Seo, J.; Kim, Y.; Lee, J.; Son, E.; Jung, M.-H.; Kim, Y.-M.; Jeong, H. Y.; Lee, G.; Park, H. A single-atom vanadium-doped 2D semiconductor platform for attomolar-level molecular sensing. J. Mater. Chem. A 2022, 10, 13298– 13304, DOI: 10.1039/D2TA01935CGoogle Scholar146https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtlGjsr3P&md5=0b5fae6679ff7ab182ae81ea1cdee5bdA single-atom vanadium-doped 2D semiconductor platform for attomolar-level molecular sensingSeo, Jihyung; Kim, Yongchul; Lee, Junghyun; Son, Eunbin; Jung, Min-Hyoung; Kim, Young-Min; Jeong, Hu Young; Lee, Geunsik; Park, HyesungJournal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (25), 13298-13304CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Semiconducting materials offer promising opportunities as ideal platforms for localized surface plasmon resonance (LSPR)-free surface-enhanced Raman spectroscopy (SERS)-based mol. detection. However, conventional semiconductor-based SERS substrates have various drawbacks that hinder their practical SERS application, including their low sensitivity, uniformity, reproducibility, and operational stability, and poor universal detection capability for diverse analytes. Herein, we present a facile and effective strategy for boosting various aspects of the SERS functionalities of a 2D semiconductor, 1T' ReSe2, to develop a practical LSPR-free SERS platform. Upon single-atom vanadium doping, the 1T' ReSe2 substrate exhibited strong coupling interaction and efficient photoinduced charge transfer resonance with probe mols., leading to ultrahigh sensitivity with an attomolar detection limit. Moreover, the method employed for prepg. the vanadium-doped ReSe2 SERS substrate, viz., liq. precursor-assisted chem. vapor deposition-based synthesis with substitutional doping, endowed it with outstanding uniformity and reproducibility. Moreover, the as-prepd. substrate demonstrated excellent operational stability and universal detection capability owing to its side catalytic effect-free feature, unique electronic structure, and strong interaction with analytes.
- 147Liu, Y.; Gao, Z.; Chen, M.; Tan, Y.; Chen, F. Enhanced Raman scattering of CuPc films on imperfect WSe2 monolayer correlated to exciton and charge-transfer resonances. Adv. Funct. Mater. 2018, 28, 1805710, DOI: 10.1002/adfm.201805710Google ScholarThere is no corresponding record for this reference.
- 148Li, X.; Guo, S.; Su, J.; Ren, X.; Fang, Z. Efficient Raman Enhancement in Molybdenum Disulfide by Tuning the Interlayer Spacing. ACS Appl. Mater. Interfaces 2020, 12 (25), 28474– 28483, DOI: 10.1021/acsami.0c04151Google Scholar148https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtVaqsL3N&md5=e5e299feb895b9f7eda52cf65a8b72dfEfficient Raman Enhancement in Molybdenum Disulfide by Tuning the Interlayer SpacingLi, Xuanhua; Guo, Shaohui; Su, Jie; Ren, Xingang; Fang, ZheyuACS Applied Materials & Interfaces (2020), 12 (25), 28474-28483CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Two-dimensional nanomaterials, such as graphene and molybdenum disulfide (MoS2), have recently attracted widespread attention as surface-enhanced Raman scattering (SERS) substrates. However, their SERS enhancement is of a smaller magnitude than that of noble metal nanomaterials, and therefore, the detection sensitivity still needs to be substantially improved for practical applications. Here, we present the first detailed studies on the effect of the (MoS2) interlayer distances on the SERS intensity enhancement. We find that MoS2 with smaller interlayer distances achieves an SERS enhancement factor as high as 5.31 x 105, which is one of the highest enhancement factors to date among the two-dimensional nanomaterial SERS sensors. This remarkable SERS sensitivity is attributed to the highly efficient charge transfer from MoS2 to probe mols. The charge-transfer ability directly dets. the variable quantity dz2 orbitals of Mo elements in the MoS2-mol. system and then tunes the Raman intensity of probe mols. Our work contributes to reveal the influence of MoS2 interlayer spacing on SERS detection and to open a new way for designing a highly sensitive nonmetal SERS technol.
- 149Sun, L.; Hu, H.; Zhan, D.; Yan, J.; Liu, L.; Teguh, J. S.; Yeow, E. K. L.; Lee, P. S.; Shen, Z. Plasma modified MoS2 nanoflakes for surface enhanced Raman scattering. Small 2014, 10, 1090– 1095, DOI: 10.1002/smll.201300798Google Scholar149https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXisFWjtr4%253D&md5=61a81c3f4b08b75e81a71d545503358aPlasma Modified MoS2 Nanoflakes for Surface Enhanced Raman ScatteringSun, Linfeng; Hu, Hailong; Zhan, Da; Yan, Jiaxu; Liu, Lei; Teguh, Jefri S.; Yeow, Edwin K. L.; Lee, Pooi See; Shen, ZexiangSmall (2014), 10 (6), 1090-1095CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)The authors obsd. an improved Raman enhancement of Rhodamine 6G (R6G) mols. deposited on oxygen-plasma treated MoS2 (OT-MoS2) and argon plasma treated MoS2 (AT-MoS2) nanoflakes.
- 150Pan, C.; Song, J.; Sun, J.; Wang, Q.; Wang, F.; Tao, W.; Jiang, L. One-Step Fabrication Method of MoS2 for High-Performance Surface-Enhanced Raman Scattering. J. Phys. Chem. C 2021, 125, 24550– 24556, DOI: 10.1021/acs.jpcc.1c05340Google Scholar150https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitlCmtr%252FM&md5=798ffb01d647ff4342e49c533ec9e3dcOne-Step Fabrication Method of MoS2 for High-Performance Surface-Enhanced Raman ScatteringPan, Changji; Song, Jichao; Sun, Jingya; Wang, Qingsong; Wang, Feifei; Tao, Wenpan; Jiang, LanJournal of Physical Chemistry C (2021), 125 (44), 24550-24556CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)A 1-step method was proposed to prep. a high-performance surface-enhanced Raman scattering (SERS) substrate based on bulk MoS2 via femtosecond laser pulse modification. The Raman spectra of Rhodamine 6G (R6G) mols. were measured on different laser fluence treatment substrates with various soln. concns. The most optimized laser-treated MoS2 substrate showed a large Raman enhancement factor of 1.67 × 105 and extremely high sensitivity for detection of R6G mols., even down to 10-8 M. The morphol. characterization, luminescence measurement, and electromagnetic simulation were used to reveal the laser treatment-dependent Raman enhancement mechanism. The p-doping effect induced by O absorption led to holes filling on the top of the valence band after the laser treatment, which can enhance the charge transfer between MoS2 and R6G mols. and finally lead to the SERS effect. This method can provide a high-performance and cost-efficient way to prep. SERS substrates.
- 151Ma, Y.; Dai, Y.; Guo, M.; Niu, C.; Huang, B. Graphene adhesion on MoS2 monolayer: An ab initio study. Nanoscale 2011, 3, 3883– 3887, DOI: 10.1039/c1nr10577aGoogle Scholar151https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXht1WjsbfK&md5=20f4e768b0cddbaa5ff98c2879678fcfGraphene adhesion on MoS2 monolayer: an ab initio studyMa, Yandong; Dai, Ying; Guo, Meng; Niu, Chengwang; Huang, BaibiaoNanoscale (2011), 3 (9), 3883-3887CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)The geometric and electronic structures of graphene adsorption on MoS2 monolayer have been studied by using d. functional theory. It is found that graphene is bound to MoS2 with an interlayer spacing of 3.32 Å and with a binding energy of -23 meV per C atom irresp. of adsorption arrangement, indicating a weak interaction between graphene and MoS2. A detailed anal. of the electronic structure indicates that the nearly linear band dispersion relation of graphene can be preserved in MoS2/graphene hybrid accompanied by a small band-gap (2 meV) opening due to the variation of on-site energy induced by MoS2. These findings are useful complement to exptl. studies of this new synthesize system and suggest a new route to facilitate the design of devices where both finite band-gap and high carrier mobility are needed.
- 152Ghopry, S. A.; Alamri, M. A.; Goul, R.; Sakidja, R.; Wu, J. Z. Extraordinary Sensitivity of Surface-Enhanced Raman Spectroscopy of Molecules on MoS2 (WS2) Nanodomes/Graphene van der Waals Heterostructure Substrates. Adv. Optical Mater. 2019, 7, 1801249, DOI: 10.1002/adom.201801249Google ScholarThere is no corresponding record for this reference.
- 153Tan, Y.; Ma, L.; Gao, Z.; Chen, M.; Chen, F. Two-dimensional heterostructure as a platform for surface-enhanced Raman scattering. Nano Lett. 2017, 17, 2621– 2626, DOI: 10.1021/acs.nanolett.7b00412Google Scholar153https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXltlWisr8%253D&md5=da305fd66bc06d70eae6cfb0334606ffTwo-Dimensional Heterostructure as a Platform for Surface-Enhanced Raman ScatteringTan, Yang; Ma, Linan; Gao, Zhinbin; Chen, Ming; Chen, FengNano Letters (2017), 17 (4), 2621-2626CODEN: NALEFD; ISSN:1530-6984. (American Chemical Society)Raman enhancement on a flat nonmetallic surface has attracted increasing attention, ever since the discovery of graphene enhanced Raman scattering. Recently, diverse two-dimensional layered materials have been applied as a flat surface for the Raman enhancement, attributed to different mechanisms. Looking beyond these isolated materials, at. layers can be reassembled to design a heterostructure stacked layer by layer with an arbitrary chosen sequence, which allows the flow of charge carriers between neighboring layers and offers novel functionalities. Here, we demonstrate the heterostructure as a novel Raman enhancement platform. The WSe2 (W) monolayer and graphene (G) were stacked together to form a heterostructure with an area of 10 mm × 10 mm. Heterostructures with different stacked structuress are used as platforms for the enhanced Raman scattering, including G/W, W/G, G/W/G/W, and W/G/G/W. On the surface of the heterostructure, the intensity of the Raman scattering is much stronger compared with isolated layers, using the copper phthalocyanine (CuPc) mol. as a probe. It is found that the Raman enhancement effect on heterostructures depends on stacked methods. Phonon modes of CuPc have the strongest enhancement on G/W. W/G and W/G/G/W have a stronger enhancement than that on the isolated WSe2 monolayer, while lower than the graphene monolayer. The G/W/G/W/substrate demonstrated a comparable Raman enhancement effect than the G/W/substrate. These differences are due to the different interlayer couplings in heterostructures related to electron transition probability rates, which are further proved by first-principle calcns. and probe-pump measurements.
- 154Wu, D.; Chen, J.; Ruan, Y.; Sun, K.; Zhang, K.; Xie, W.; Xie, F.; Zhao, X.; Wang, X. A novel sensitive and stable surface enhanced Raman scattering substrate based on a MoS2 quantum dot/reduced graphene oxide hybrid system. J. Mater. Chem. C 2018, 6, 12547– 12554, DOI: 10.1039/C8TC05151HGoogle Scholar154https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvFKks77E&md5=07d3cc17afef58b1d4b4924d1857f2f5A novel sensitive and stable surface enhanced Raman scattering substrate based on a MoS2 quantum dot/reduced graphene oxide hybrid systemWu, Di; Chen, Jianli; Ruan, Yaner; Sun, Kai; Zhang, Kehua; Xie, Wenjie; Xie, Fazhi; Zhao, Xiaoli; Wang, XiufangJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2018), 6 (46), 12547-12554CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)A MoS2 quantum dot/reduced graphene oxide (MoS2 QD/rGO) nanocomposite has been synthesized by a simple hydrothermal approach. For the first time, the MoS2 QD/rGO composite is used as a highly sensitive and stable surface enhanced Raman scattering (SERS) substrate to detect trace amts. of mol. species. The lowest detection limit (LOD) for rhodamine 6G (R6G) is as low as 1 × 10-9 M with the max. enhancement factor (EF) of up to 1.20 × 107, which is the best among the non-noble metal SERS materials. For practical applications, the MoS2 QD/rGO SERS substrate is also used to detect methylene blue (MB) in deionized water and river water. The LOD (1 × 10-8 M) is obtained in river water, which demonstrates the high feasibility for multi-mol. detection and vast potential ability for the detection of chem. and biol. mols. The enhancement mechanism of the MoS2 QD/rGO SERS substrate is studied, and the large enhancement of the SERS signal is due to the charge transfer (CT) state formed at the interface of the 1T-phase MoS2 QDs with small size and ultrathin slices and org. mols. The chem. enhancement of rGO also contributes to the SERS enhancement. The study paves a new way for designing a novel MoS2 QD-based SERS substrate.
- 155Qiu, H.; Wang, M.; Zhang, L.; Cao, M.; Ji, Y.; Kou, S.; Dou, J.; Sun, X.; Yang, Z. Wrinkled 2H-phase MoS2 sheet decorated with graphene-microflowers for ultrasensitive molecular sensing by plasmon-free SERS enhancement. Sens. Actuators, B 2020, 320, 128445, DOI: 10.1016/j.snb.2020.128445Google Scholar155https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXht1aks7bJ&md5=c921be6a3386cbd7024ca864946b34e3Wrinkled 2H-phase MoS2 sheet decorated with graphene-microflowers for ultrasensitive molecular sensing by plasmon-free SERS enhancementQiu, Hengwei; Wang, Minqiang; Zhang, Lin; Cao, Minghui; Ji, Yongqiang; Kou, Song; Dou, Jinjuan; Sun, Xiaoqiang; Yang, ZhiSensors and Actuators, B: Chemical (2020), 320 (), 128445CODEN: SABCEB; ISSN:0925-4005. (Elsevier B.V.)High surface-enhanced Raman spectroscopy (SERS) activity is ordinarily derived from noble-metal nanoarrays. In recent years, certain two-dimensional (2D) inorg. materials have become suitable for SERS. However, the limits of detection (LODs) of these plasmon-free materials are insufficient for meeting the requirements of mol. anal. Herein, the centralization of the probe mol. pre-concn. process, and enhancement of interfacial interactions between the substrate and mols. were pivotal accomplishments in the development of a hetero-substrate comprised of a wrinkled semiconducting 2H-phase MoS2 (W-MoS2) platform decorated with graphene-microflowers (GMFs), for the achievement of noble-metal-comparable SERS detection. The GMFs served as supersized mol. enrichers, creating abundant SERS 'active regions', and thus, the LOD in the adsorption equil. state was 5 x 10-11 M for rhodamine B (RhB), and the max. enhancement factor (EF) was 2.96 x 107. Addnl., performance degrdn. of GMFs/W-MoS2 was below 6%, following long-term detection over 50 days. The sub-nanomolar sensitivity of the GMFs/W-MoS2 substrate can be attributed to the synergistic effects of the efficacious pre-concn. of probe mols., enhanced charge-transfer, and multiple light scattering, all of which can promote the progress of plasmon-free SERS detection.
- 156Lv, Q.; Tan, J.; Wang, Z.; Gu, P.; Liu, H.; Yu, L.; Wei, Y.; Gan, L.; Liu, B.; Li, J. Ultrafast charge transfer in mixed-dimensional WO3-x nanowire/WSe2 heterostructures for attomolar-level molecular sensing. Nat. Commun. 2023, 14 (1), 2717, DOI: 10.1038/s41467-023-38198-xGoogle ScholarThere is no corresponding record for this reference.
- 157Tan, L.; Yue, S.; Lou, Y.; Zhu, J.-J. Enhancing charge transfer in a W18O49/g-C3N4 heterostructure via band structure engineering for effective SERS detection and flexible substrate applications. Analyst 2024, 149, 180– 187, DOI: 10.1039/D3AN01690KGoogle ScholarThere is no corresponding record for this reference.
- 158Majumdar, D. Surface-enhanced Raman effect on MoS2–WS2 composite structures. Appl. Phys. A: Mater. Sci. Process. 2024, 130, 289, DOI: 10.1007/s00339-024-07454-2Google ScholarThere is no corresponding record for this reference.
- 159Chen, L.; Hou, H.-L.; Prato, M. Impact of the Interlayer Distance between Graphene and MoS2 on Raman Enhancement. Chem. Mater. 2023, 35 (13), 5032– 5039, DOI: 10.1021/acs.chemmater.3c00479Google ScholarThere is no corresponding record for this reference.
- 160Gogotsi, Y.; Anasori, B. The Rise of MXenes. ACS Nano 2019, 13 (8), 8491– 8494, DOI: 10.1021/acsnano.9b06394Google Scholar160https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhs1Shsb3I&md5=80f99f913be8a854f89752a808f88790The Rise of MXenesGogotsi, Yury; Anasori, BabakACS Nano (2019), 13 (8), 8491-8494CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)There is no expanded citation for this reference.
- 161Naguib, M.; Kurtoglu, M.; Presser, V.; Lu, J.; Niu, J.; Heon, M.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W. Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2. Adv. Mater. 2011, 23, 4248– 4253, DOI: 10.1002/adma.201102306Google Scholar161https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhtVGisLnL&md5=2c476f3f7f645d96680e0f4c9c3513e0Two-Dimensional Nanocrystals Produced by Exfoliation of Ti3AlC2Naguib, Michael; Kurtoglu, Murat; Presser, Volker; Lu, Jun; Niu, Junjie; Heon, Min; Hultman, Lars; Gogotsi, Yury; Barsoum, Michel W.Advanced Materials (Weinheim, Germany) (2011), 23 (37), 4248-4253CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Treatment of Ti3AlC2 powders for 2 h in HF results in the formation of exfoliated 2-dimensional (2D) Ti3C2 layers (nanosheets). The Ti3AlC2 structure is composed of individual Ti3C2 layers sepd. by Al atoms. Upon reaction with HF, Al atoms are removed from between the layers, resulting in the exfoliation of individual Ti3C2 layers from each other due to the loss of metallic bonding holding them together when the Al atoms are present. The exposed 2D Ti3C2 layers possess 2 exposed Ti atoms per unit formula that should be satisfied by suitable ligands. Since the expts. were conducted in an aq. environment rich in F ions, hydroxyl and F are the most probable ligands. Modeling of each case was conduced by attaching resp. ligands to the exposed Ti atoms followed by full geometry optimizations. The exposed Ti surfaces appear to be terminated by OH and/or F. The large elastic moduli predicted by ab initio simulation, and the possibility of varying their surface chem. render these nanosheets attractive as polymer composite fillers. The implications and importance of this work extend far beyond the results shown herein. There are over 60 currently known MAX phases; therefore, this work, in principle, opens the door for formation of a large no. of 2D Mn+1Xn structures, including the carbides and nitrides of Ti, V, Cr, Nb, Ta, Hf, and Zr. The latter could include 2D structures of combination of M-atoms, e.g., Ti0.5Zr0.5InC and/or different combinations of C and N, such as Ti2AlC0.5N0.5, if the selective chem. etching is extended to other MAX phases. We currently have solid evidence for the exfoliation of Ta4AlC3 into Ta4C3 flakes.
- 162Naguib, M.; Mashtalir, O.; Carle, J.; Presser, V.; Lu, J.; Hultman, L.; Gogotsi, Y.; Barsoum, M. W. Two-Dimensional Transition Metal Carbides. ACS Nano 2012, 6 (2), 1322– 1331, DOI: 10.1021/nn204153hGoogle Scholar162https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38Xht1OitbY%253D&md5=7b170cfc2286798534164272c0fd0f5aTwo-Dimensional Transition Metal CarbidesNaguib, Michael; Mashtalir, Olha; Carle, Joshua; Presser, Volker; Lu, Jun; Hultman, Lars; Gogotsi, Yury; Barsoum, Michel W.ACS Nano (2012), 6 (2), 1322-1331CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The synthesis of two-dimensional transition metal carbides and carbonitrides by immersing select MAX phase powders in hydrofluoric acid, HF, is described. The MAX phases represent a large (>60 members) family of ternary, layered, machinable transition metal carbides, nitrides, and carbonitrides. We present evidence for the exfoliation of the following MAX phases: Ti2AlC, Ta4AlC3, (Ti0.5,Nb0.5)2AlC, (V0.5,Cr0.5)3AlC2, and Ti3AlCN by the simple immersion of their powders, at room temp., in HF of varying concns. for times varying between 10 and 72 h followed by sonication. The removal of the "A" group layer from the MAX phases results in 2-D layers that we are labeling MXenes to denote the loss of the A element and emphasize their structural similarities with graphene. The sheet resistances of the MXenes were found to be comparable to multilayer graphene. Contact angle measurements with water on pressed MXene surfaces showed hydrophilic behavior.
- 163Sarycheva, A.; Makaryan, T.; Maleski, K.; Satheeshkumar, E.; Melikyan, A.; Minassian, H.; Yoshimura, M.; Gogotsi, Y. Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering Substrate. J. Phys. Chem. C 2017, 121 (36), 19983– 19988, DOI: 10.1021/acs.jpcc.7b08180Google Scholar163https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtlKnsbzL&md5=5e70b1508ae0aac3af169ef3237fe5a4Two-Dimensional Titanium Carbide (MXene) as Surface-Enhanced Raman Scattering SubstrateSarycheva, Asia; Makaryan, Taron; Maleski, Kathleen; Satheeshkumar, Elumalai; Melikyan, Armen; Minassian, Hayk; Yoshimura, Masahiro; Gogotsi, YuryJournal of Physical Chemistry C (2017), 121 (36), 19983-19988CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)Noble metal (Au or Ag) nanoparticles or patterned films are typically used as substrates for surface-enhanced Raman spectroscopy (SERS). Two-dimensional (2D) carbides and nitrides (MXenes) exhibit unique electronic and optical properties, including metallic cond. and plasmon resonance in the visible or near-IR range, making them promising candidates for a wide variety of applications. 2D Ti carbide, Ti3C2Tx, enhances Raman signal from org. dyes on a substrate and in soln. As a proof of concept, MXene SERS substrates were manufd. by spray-coating and used to detect several common dyes, with calcd. enhancement factors reaching ∼106. Ti carbide MXene demonstrates SERS effect in aq. colloidal solns., suggesting the potential for biomedical or environmental applications, where MXene can selectively enhance pos. charged mols.
- 164Shevchuk, K.; Sarycheva, A.; Gogotsi, Y. Evaluation of two-dimensional transition-metal carbides and carbonitrides (MXenes) for SERS substrates. MRS Bull. 2022, 47, 545– 554, DOI: 10.1557/s43577-022-00276-8Google Scholar164https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xht1Gqs7rE&md5=91ef071900f1406f0bbc5b0117984fe1Evaluation of two-dimensional transition-metal carbides and carbonitrides (MXenes) for SERS substratesShevchuk, Kateryna; Sarycheva, Asia; Gogotsi, YuryMRS Bulletin (2022), 47 (6), 545-554CODEN: MRSBEA; ISSN:1938-1425. (Springer International Publishing AG)Abstr.: This initial report demonstrates the family of two-dimensional transition-metal carbides and carbonitrides (MXenes) as promising plasmonic materials for surface-enhanced Raman spectroscopy (SERS), allowing sensitive detection of analyte mols. Their surface plasmon resonances, metallic characters, and rich surface chemistries enable both SERS electromagnetic and chem. enhancements. We have synthesized seven MXenes-Nb2C, Mo2C, Ti2C, V2C, Ti3C2, Mo2TiC2, and Ti3CN, of which only Ti3C2 and Nb2C have been explored as pristine substrates for SERS applications. All explored MXenes could detect the 10-7 M concns. of Rhodamine 6G dye. Ti3C2 and Ti2C show the highest enhancement and were compared to the com. available substrates, where Ti3C2 outperformed gold nanoparticles. Addnl., the best-performing MXene was tested with a variety of dyes, suggesting the versatility of MXene sensing. Due to high charge carrier densities and tunable surface chemistries, MXenes show potential for SERS sensors that are inexpensive, easy to fabricate and optimize for specific applications. Impact statement: Surface-enhanced Raman spectroscopy is a powerful, non-destructive anal. tool that provides high selectivity and sensitivity and could be used for single-mol. characterization. It allows for fast detection of environmental pollutants and toxins, as well as biosensing and environmental monitoring. However, the prevalence of the application is limited by the cost and stability of com. available substrates that employ noble metal nanostructures (Ag, Au, Pt). Recent research activities have focused on discovering new enhancing substrates: the Ti3C2 MXene has been gaining interest as a SERS substrate due to its surface plasmon resonance, metallic behavior, and surface terminations, achieving the record-setting enhancement factors. In contrast, this study elucidates the capability of MXenes beyond Ti3C2 to perform as SERS substrates. We showed that Nb2C, Mo2C, Ti2C, V2C, Ti3C2, Mo2TiC2, and Ti3CN MXenes could detect low concns. of dye mols. Furthermore, compared to the com. gold nanoparticle substrate, Ti3C2 showed advantageous performance. There are approx. 50 MXenes that have been synthesized to date. Their high charge carrier densities and tunable surface chemistries open the avenues of SERS detection of various analytes, with the perspective of replacing noble metals with materials made of earth-abundant elements. This would make SERS more accessible for biomedical, environmental, and forensic applications. Graphical abstr.: [graphic not available: see fulltext].
- 165Limbu, T. B.; Chitara, B.; Garcia Cervantes, M. Y.; Zhou, Y.; Huang, S. Y.; Tang, Y.; Yan, F. Unravelling the Thickness Dependence and Mechanism of Surface-Enhanced Raman Scattering on Ti3C2TX MXene Nanosheets. J. Phys. Chem. C 2020, 124 (32), 17772– 17782, DOI: 10.1021/acs.jpcc.0c05143Google Scholar165https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVSmsLvO&md5=d66b55d2ce9fc8a8c457800dd48562b0Unravelling the Thickness Dependence and Mechanism of Surface-Enhanced Raman Scattering on Ti3C2TX MXene NanosheetsLimbu, Tej B.; Chitara, Basant; Garcia Cervantes, Martha Y.; Zhou, Yu; Huang, Shengxi; Tang, Yongan; Yan, FeiJournal of Physical Chemistry C (2020), 124 (32), 17772-17782CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)MXenes have attracted great attention as promising substrates for surface-enhanced Raman scattering (SERS) applications. However, the underlying SERS mechanism has not been a focus of any investigation. Herein, we report the first systematic exptl. study on the SERS activity of titanium carbide (Ti3C2TX) nanosheets with thicknesses ranging from 5 to 120 nm, using methylene blue (MB) as a probe mol. The exptl. and math. modeling results show that the Raman enhancement factor (EF) increases monotonically with the increasing thickness of Ti3C2TX nanosheets; however, it falls drastically around a sheet thickness of 0.8 and 1.0μm under 532 and 633 nm laser excitations, resp. The Raman EF reaches a max. value around a thickness of 2.0μm, suggesting that a max. EF can be achieved with a 2.0μm-thick Ti3C2TX film substrate. The thickness dependence of the Raman enhancement can be accounted for by the adsorption and intercalation of MB mols. into the interlayer spacing of Ti3C2TX. Furthermore, by combining exptl. observations and numerical calcn., we confirm that the charge-transfer mechanism is dominantly responsible for Raman enhancement on Ti3C2TX. Addnl., we report an observation of resonance coupling of charge transfer and mol. transition as a contributing factor to the higher EF obtained with a 633 nm laser excitation. Taken together, these findings have significant implications for cost and performance optimization in designing MXene-based SERS substrates for next-generation chem. and biol. sensing platforms.
- 166Liu, R.; Jiang, L.; Lu, C.; Yu, Z.; Li, F.; Jing, X.; Xu, R.; Zhou, W.; Jin, S. Large-scale two-dimensional titanium carbide MXene as SERS-active substrate for reliable and sensitive detection of organic pollutants. Spectrochim. Acta, Part A 2020, 236, 118336, DOI: 10.1016/j.saa.2020.118336Google Scholar166https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXnsFaitr8%253D&md5=45cc06d1e651c2363b584267105992f2Large-scale two-dimensional titanium carbide MXene as SERS-active substrate for reliable and sensitive detection of organic pollutantsLiu, Rongyang; Jiang, Li; Lu, Chengxing; Yu, Zizhen; Li, Fanghao; Jing, Xufeng; Xu, Rui; Zhou, Wei; Jin, ShangzhongSpectrochimica Acta, Part A: Molecular and Biomolecular Spectroscopy (2020), 236 (), 118336CODEN: SAMCAS; ISSN:1386-1425. (Elsevier B.V.)As a new class of two-dimensional material, MXene not only has the unique planar structure, electronic and optical properties, but also has a large surface area and hydrophilicity, which make them to build as potential SERS substrates with good sensitivity and stability. In this work, we reported a modified method by adjusting the ratio of HCl to LiF and reducing sonicate time to form large-sized monolayer Ti3C2Tx nanosheets. SERS performance of Ti3C2Tx was demonstrated by detecting dye mols. such as CV, R6G and MG. A remarkable enhanced effect was obtained, and Raman signals up to 10-8 M could be detected. Furthermore, the relationship between SERS effects and illumination laser wavelengths of different probe mols. has been studied, the results showed the selectivity between dye mols. and the excitation wavelengths. Besides, the uniformity and stability of the substrates have been proved by mapping expts. in a large area (80 x 80 μm2). The results demonstrated that Ti3C2Tx nanosheets can be built as lager-sized, uniform and stable sensor for ultra-sensitive detection of org. dye pollutant mols.
- 167Soundiraraju, B.; George, B. K. Two-dimensional titanium nitride (Ti2N) MXene: synthesis, characterization, and potential application as surface-enhanced Raman scattering substrate. ACS Nano 2017, 11, 8892– 8900, DOI: 10.1021/acsnano.7b03129Google Scholar167https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtl2lsLbE&md5=1e1c23eefee3cd134cee4476ca51d6b4Two-Dimensional Titanium Nitride (Ti2N) MXene: Synthesis, Characterization, and Potential Application as Surface-Enhanced Raman Scattering SubstrateSoundiraraju, Bhuvaneswari; George, Benny KattikkanalACS Nano (2017), 11 (9), 8892-8900CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The authors report on the synthesis, characterization, and application of Ti2N (MXene), a two-dimensional transition metal nitride of M2X type. Synthesis of nitride-based MXenes (Mn+1Nn) is difficult due to their higher formation energy from Mn+1ANn and poor stability of Mn+1Nn layers in the etchant employed, typically HF. Herein, the selective etching of Al from ternary layered transition metal nitride Ti2AlN (MAX) and intercalation were achieved by immersing the powder in a mixt. of potassium fluoride and hydrochloric acid. The multilayered Ti2NTx (T is the surface termination) obtained was sonicated in DMSO and centrifuged to obtain few-layered Ti2NTx. MXene formation was verified, and the material was completely characterized by Raman spectroscopy, XRD, XPS spectra, FESEM-EDS, TEM, STM, and AFM techniques. Surface-enhanced Raman scattering (SERS) activity of the synthesized Ti2NTx was investigated by fabricating paper, silicon, and glass-based SERS substrates. A Raman enhancement factor of 1012 was demonstrated using rhodamine 6G as the model compd. with 532 nm excitation wavelength. Detection of trace level explosives with a simple paper-based SERS substrate with Ti2N (MXene) as active material was also illustrated.
- 168He, Z.; Rong, T.; Li, Y.; Ma, J.; Li, Q.; Wu, F.; Wang, Y.; Wang, F. Two-Dimensional TiVC Solid-Solution MXene as Surface-Enhanced Raman Scattering Substrate. ACS Nano 2022, 16 (3), 4072– 4083, DOI: 10.1021/acsnano.1c09736Google Scholar168https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XjvVOrt7w%253D&md5=f7ab52c240b4042aff74ccb6c82bdf82Two-Dimensional TiVC Solid-Solution MXene as Surface-Enhanced Raman Scattering SubstrateHe, Zhiquan; Rong, Tengda; Li, Yan; Ma, Junjie; Li, Quanshui; Wu, Furong; Wang, Yuhang; Wang, FengpingACS Nano (2022), 16 (3), 4072-4083CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Two-dimensional (2D) MXenes are attractive candidates as surface-enhanced Raman scattering (SERS) substrates because of their metallic cond. and abundant surface terminations. Herein, we report the facile synthesis of bimetallic solid-soln. TiVC (MXene) and its application in SERS. The few-layered MXene nanosheets with high crystallinity were successfully prepd. using a one-step chem. etching method without ultrasonic and org. solvent intercalation steps. SERS activity of the as-prepd. MXene was investigated by fabricating free-standing TiVC film as the substrate. A SERS enhancement factor of 1012 and femtomolar-level detection limit were confirmed using rhodamine 6G as a model dye with 532 nm excitation. The fluorescent signal of the rhodamine 6G dye was effectively quenched, making the SERS spectrum clearly distinguishable. Furthermore, we demonstrate that the TiVC-analyte system with ultrahigh sensitivity is dominated by the chem. mechanism (CM) based on the exptl. and simulation results. The abundant d. of states near the Fermi level of the TiVC and the strong interaction between the TiVC and analyte promote the intermol. charge transfer resonance in the TiVC-analyte complex, resulting in significant Raman enhancement. Addnl., several other probe mols. were used for SERS detection to further verify CM-based selectivity enhancement on the TiVC substrates. This work provides guidance for the facile synthesis of 2D MXene and its application in ultrasensitive SERS detection.
- 169Satheeshkumar, E.; Makaryan, T.; Melikyan, A.; Minassian, H.; Gogotsi, Y.; Yoshimura, M. One-step Solution Processing of Ag, Au and Pd@MXene Hybrids for SERS. Sci. Rep. 2016, 6, 32049, DOI: 10.1038/srep32049Google Scholar169https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhsVantb3N&md5=803470d0c194c74b71542065515abd43One-step Solution Processing of Ag, Au and Pd@MXene Hybrids for SERSSatheeshkumar, Elumalai; Makaryan, Taron; Melikyan, Armen; Minassian, Hayk; Gogotsi, Yury; Yoshimura, MasahiroScientific Reports (2016), 6 (), 32049CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)We report on one-step hybridization of silver, gold and palladium nanoparticles from soln. onto exfoliated two-dimensional (2D) Ti3C2 titanium carbide (MXene) nanosheets. The produced hybrid materials can be used as substrates for surface-enhanced Raman spectroscopy (SERS). An approx. anal. approach is also developed for the calcn. of the surface plasmon resonance (SPR) frequency of nanoparticles immersed in a medium, near the interface of two dielec. media with different dielec. consts. We obtained a good match with the exptl. data for SPR wavelengths, 440 nm and 558 nm, resp. for silver and gold nanoparticles. In the case of palladium, our calcd. SPR wavelength for the planar geometry was 160 nm, demonstrating that non-spherical palladium nanoparticles coupled with 2D MXene yield a broad, significanlty red-shifted SPR band with a peak at 230 nm. We propose a possible mechanism of the plasmonic hybridization of nanoparticles with MXene. The as-prepd. noble metal nanoparticles on MXene show a highly sensitive SERS detection of methylene blue (MB) with calcd. enhancement factors on the order of 105. These findings open a pathway for extending visible-range SERS applications of novel 2D hybrid materials in sensors, catalysis, and biomedical applications.
- 170Wang, T.; Dong, P.; Zhu, C.; Gao, W.; Sha, P.; Wu, Y.; Wu, X. Fabrication of 2D titanium carbide MXene/Au nanorods as a nanosensor platform for sensitive SERS detection. Ceram. Int. 2021, 47, 30082– 30090, DOI: 10.1016/j.ceramint.2021.07.184Google Scholar170https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhs1alu7bF&md5=fe92aefc3ec643f65b6aaafa99852513Fabrication of 2D titanium carbide MXene/Au nanorods as a nanosensor platform for sensitive SERS detectionWang, Tianran; Dong, Peitao; Zhu, Chushu; Gao, Weiye; Sha, Pengxing; Wu, Yulie; Wu, XuezhongCeramics International (2021), 47 (21), 30082-30090CODEN: CINNDH; ISSN:0272-8842. (Elsevier Ltd.)As an emerging label-free detection technol., surface-enhanced Raman scattering (SERS) has been used for biol. detection, food safety, and environmental pollution owing to its high sensitivity, specificity and rapid response. However, traditional SERS substrates are unstable, prone to agglomeration, and demonstrate low productivity and high prodn. cost. In this work, hybrids of a two-dimensional electron gas (2DEG) Ti3C2Tx monolayer and Au nanorods (AuNRs) were fabricated via self-assembly. Ti3C2Tx:AuNRs ratios were prepd., and each hybrid's SERS activity was evaluated through 4-aminothiophenol (pATP) detection. The Ti3C2Tx/AuNRs-1 substrate exhibited the weakest SERS performance, whereas the Ti3C2Tx/AuNRs-3 substrate had the best SERS activity enhancement, with a pATP limit of detection (LOD) of 10-9 M. When 30 sites on substrates were selected for SERS detection, the relative std. deviation (RSD) was found to be only 7.18%, revealing the good performance sensitivity and high reproducibility of the Raman signal. The sensitivity of Ti3C2Tx/AuNRs-3 was also assessed with respect to a hazardous chem., 1,2-bis (4-pyridyl) ethylene (BPE), revealing an LOD of 10-12 M. For thiram, the LOD of Ti3C2Tx/AuNRs-3 was 10-8 M, which is considerably lower than the 1 ppm industry safety std. A relative std. deviation RSD of 7.94% indicates the high reproducibility and uniformity of the Raman signal of thiram for Ti3C2Tx/AuNRs-3. Compared with the LODs of 10-5 M and 10-6 M for com. substrates T-SERS and Au nanorod arrays (AuNRAs), resp., the 10-8 M LOD of our synthesized Ti3C2Tx/AuNRs indicates good sensitivity. Three kinds of pesticides were detected by Ti3C2Tx/AuNRs, and only Raman signal of thiram can be found, revealing the good selectivity for thiram. These results for Ti3C2Tx/AuNRs suggest its potential to serve as a novel SERS platform.
- 171Xie, H.; Li, P.; Shao, J.; Huang, H.; Chen, Y.; Jiang, Z.; Chu, P. K.; Yu, X.-F. Electrostatic Self-Assembly of Ti3C2Tx MXene and Gold Nanorods as an Efficient Surface-Enhanced Raman Scattering Platform for Reliable and High-Sensitivity Determination of Organic Pollutants. ACS Sens. 2019, 4 (9), 2303– 2310, DOI: 10.1021/acssensors.9b00778Google Scholar171https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXhsFWmsLzL&md5=1f5955220b2a6ceb8c5fb9c9e96540d9Electrostatic Self-Assembly of Ti3C2Tx MXene and Gold Nanorods as an Efficient Surface-Enhanced Raman Scattering Platform for Reliable and High-Sensitivity Determination of Organic PollutantsXie, Hanhan; Li, Penghui; Shao, Jundong; Huang, Hao; Chen, Yue; Jiang, Zhenyou; Chu, Paul K.; Yu, Xue-FengACS Sensors (2019), 4 (9), 2303-2310CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)A reliable surface-enhanced Raman scattering (SERS) substrate composed of two-dimensional (2D) MXene (Ti3C2Tx) nanosheets and gold nanorods (AuNRs) is designed and fabricated for sensitive detection of org. pollutants. The AuNRs are uniformly distributed on the surface of the 2D MXene nanosheets because of the strong electrostatic interactions, forming abundant SERS hot spots. The MXene/AuNR SERS substrate exhibits high sensitivity and excellent reproducibility in the detn. of common org. dyes such as rhodamine 6G, crystal violet, and malachite green. The detection limits are 1 × 10-12, 1 × 10-12, and 1 × 10-10 M, and relative std. deviations detd. from 13 areas on each sample are 18.1, 10.1, and 15.6%, resp. In the detn. of more complex org. pesticides and pollutants, the substrate also shows excellent sensitivity and quant. detection, and the detection limits for thiram and diquat of 1 × 10-10 and 1 × 10-8 M, resp., are much lower than the contaminant levels stipulated by the US Environmental Protection Agency. The MXene/AuNR composite constitutes an efficient SERS platform for reliable and high-sensitivity environmental anal. and food safety monitoring.
- 172Yusoff, N. N.; Nor Azmi, F. S.; Abu Bakar, N.; Tengku Abdul Aziz, T. H.; Shapter, J. G. Titanium carbide MXene/silver nanostars composite as SERS substrate for thiram pesticide detection. Chem. Pap. 2024, 78, 2855– 2865, DOI: 10.1007/s11696-023-03276-3Google ScholarThere is no corresponding record for this reference.
- 173Bai, Y.; Otitoju, T. A.; Wang, Y.; Chen, Q.; Sun, T. Highly sensitive in situ SERS monitoring of Fenton-like reaction by a PDDA-MXene@AuNP composite. New J. Chem. 2023, 47, 5174– 5178, DOI: 10.1039/d2nj05921eGoogle ScholarThere is no corresponding record for this reference.
- 174Peng, Y.; Cai, P.; Yang, L.; Liu, Y.; Zhu, L.; Zhang, Q.; Liu, J.; Huang, Z.; Yang, Y. Theoretical and Experimental Studies of Ti3C2 MXene for Surface-Enhanced Raman Spectroscopy-Based Sensing. ACS Omega 2020, 5, 26486– 26496, DOI: 10.1021/acsomega.0c03009Google Scholar174https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXitVSqsrzI&md5=a2b57045bcdf2da73c784c02d60f90e6Theoretical and Experimental Studies of Ti3C2 MXene for Surface-Enhanced Raman Spectroscopy-Based SensingPeng, Yusi; Cai, Ping; Yang, Lili; Liu, Yingying; Zhu, Linfeng; Zhang, Qiuqi; Liu, Jianjun; Huang, Zhengren; Yang, YongACS Omega (2020), 5 (41), 26486-26496CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)Recent advances in MXenes with high carrier mobility show great application prospects in the surface-enhanced Raman scattering (SERS) field. However, challenges remain regarding the improvement of the SERS sensitivity. Herein, an effective strategy considering charge-transfer resonance for semiconductor-based substrates is presented to optimize the SERS sensitivity with the guidance of the d. functional theory calcn. The theor. calcn. predicted that the excellent SERS enhancement for methylene blue (MeB) on Ti3C2 MXene can be excited by both 633 and 785 nm lasers, and the Raman enhanced effect is mainly originated from the charge-transfer resonance enhancement. In this work, the Ti3C2 MXenes exhibit an excellent SERS sensitivity with an enhancement factor of 2.9 x 106 and a low detection limit of 10-7 M for MeB mols. Furthermore, the SERS enhancement of Ti3C2 and Au-Ti3C2 substrates exhibit higher selectivity on different mols., which contributes to the detection of target mols. in complex soln. environments. This work can provide some theor. and exptl. basis for the research on SERS activity of other MXene materials.
- 175Wu, Z.; Sun, D.-W.; Pu, H.; Wei, Q.; Lin, X. Ti3C2Tx MXenes loaded with Au nanoparticle dimers as a surface-enhanced Raman scattering aptasensor for AFB1 detection. Food Chem. 2022, 372, 131293, DOI: 10.1016/j.foodchem.2021.131293Google Scholar175https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXit1Kns7%252FL&md5=65dbb5b6622d02b15a1eda4f09215df4Ti3C2Tx MXenes loaded with Au nanoparticle dimers as a surface-enhanced Raman scattering aptasensor for AFB1 detectionWu, Zhihui; Sun, Da-Wen; Pu, Hongbin; Wei, Qingyi; Lin, XuanranFood Chemistry (2022), 372 (), 131293CODEN: FOCHDJ; ISSN:0308-8146. (Elsevier Ltd.)Mycotoxin B1 (AFB1) contamination in agricultural products pose a deadly danger to animal and human health and its rapid and reliable detection is thus very important. Herein, a ratiometric surface-enhanced Raman scattering (SERS) aptasensor for AFB1 detection was developed, in which 1,2-bis(4-pyridyl) ethylene (BPE) was used to trigger the assembly of Au nanoparticle dimers (AuNP dimers) and form intensive SERS "hot spots", and MXenes nanosheets could load aptamer-modified AuNP dimers due to the hydrogen bonding and the chelation between the phosphate groups of aptamers and the Ti ion of MXenes. With the presence of AFB1 preferentially binding to AFB1 aptamer, AuNP dimers were sepd. from MXenes nanosheets, leading to a decrease in SERS intensity. Regression anal. in the range from 0.001 to 100 ng·mL-1 showed the limit of detection (LOD) being 0.6 pg·mL-1 in std. soln., indicating that the great prospects of the AuNP dimers/MXenes SERS substrate for detecting AFB1.
- 176Chen, Y.; Jiang, C.; Huang, F.; Yu, Z.; Jiang, L. Efficient interfacial self-assembled MXene/Ag NPs film nanocarriers for SERS-traceable drug delivery. Anal. Bioanal. Chem. 2023, 415, 5379– 5389, DOI: 10.1007/s00216-023-04813-5Google ScholarThere is no corresponding record for this reference.
- 177Yoo, S. S.; Ho, J.-W.; Shin, D.-I.; Kim, M.; Hong, S.; Lee, J. H.; Jeong, H. J.; Jeong, M. S.; Yi, G.-R.; Kwon, S. J.; Yoo, P. J. Simultaneously intensified plasmonic and charge transfer effects in surface enhanced Raman scattering sensors using an MXene-blanketed Au nanoparticle assembly. J. Mater. Chem. A 2022, 10, 2945– 2956, DOI: 10.1039/D1TA08918HGoogle Scholar177https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhtFOluro%253D&md5=37df18a083f5533a43e95d32817a906aSimultaneously intensified plasmonic and charge transfer effects in surface enhanced Raman scattering sensors using an MXene-blanketed Au nanoparticle assemblyYoo, Seong Soo; Ho, Jeong-Won; Shin, Dong-In; Kim, Minjun; Hong, Sunghwan; Lee, Jun Hyuk; Jeong, Hyeon Jun; Jeong, Mun Seok; Yi, Gi-Ra; Kwon, S. Joon; Yoo, Pil J.Journal of Materials Chemistry A: Materials for Energy and Sustainability (2022), 10 (6), 2945-2956CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Surface enhanced Raman spectroscopy (SERS) is an ultrasensitive tool for detecting a wide range of analytes. The signal amplification is generally attributed to two different mechanisms, localized surface plasmonic resonance (LSPR) and short-range charge transfer (CT) effect between the analyte mol. and the surface of the substrate. Therefore, an assembly of metallic nanoparticles (NPs) has been employed as a basic SERS substrate. Conventional approaches based on metallic NPs for the SERS platform, however, have limitations in simultaneously eliciting both mechanisms as the energy level of most analytes is not aligned with the Fermi level of the metallic surface. Herein, this study presents the development of an ultrasensitive SERS platform utilizing a two-dimensional (2D) assembly of Au NPs conformally coated with a few-atom-thick MXene layer. The MXene layer enables the Fermi level of the substrate to be located between the HOMO and LUMO levels of analytes, thus efficiently facilitating the CT effect. In addn., wrinkled surface structures generated from conformal blanketing of the MXene layer over the Au NP assembly would help to increase the EM effect by guiding the analyte to be captured near the hotspot center between Au NPs. Thanks to this unique structural design using MXene layer deposition, the presented SERS platform exhibits a large anal. enhancement factor up to 1.6 x 1010. Furthermore, it is proven to detect Cr(VI) with a low detection limit down to 13 ng L-1. Therefore, the present SERS platform can be generalized and extended for quant. detection of a wide range of analytes including mols. of interest in biomedical and environmental aspects.
- 178Liu, X.; Dang, A.; Li, T.; Sun, Y.; Lee, T.-C.; Deng, W.; Wu, S.; Zada, A.; Zhao, T.; Li, H. Plasmonic Coupling of Au Nanoclusters on a Flexible MXene/Graphene Oxide Fiber for Ultrasensitive SERS Sensing. ACS Sens. 2023, 8 (3), 1287– 1298, DOI: 10.1021/acssensors.2c02808Google Scholar178https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3sXktF2ms78%253D&md5=5177c43ec0d8f687f4444d49144136f5Plasmonic Coupling of Au Nanoclusters on a Flexible MXene/Graphene Oxide Fiber for Ultrasensitive SERS SensingLiu, Xin; Dang, Alei; Li, Tiehu; Sun, Yiting; Lee, Tung-Chun; Deng, Weibin; Wu, Shaoheng; Zada, Amir; Zhao, Tingkai; Li, HaoACS Sensors (2023), 8 (3), 1287-1298CODEN: ASCEFJ; ISSN:2379-3694. (American Chemical Society)High sensitivity, good signal repeatability, and facile fabrication of flexible surface enhanced Raman scattering (SERS) substrates are common pursuits of researchers for the detection of probe mols. in a complex environment. However, fragile adhesion between the noble-metal nanoparticles and substrate material, low selectivity, and complex fabrication process on a large scale limit SERS technol. for wide-ranging applications. Herein, we propose a scalable and cost-effective strategy to a fabricate sensitive and mech. stable flexible Ti3C2Tx MXene@graphene oxide/Au nanoclusters (MG/AuNCs) fiber SERS substrate from wet spinning and subsequent in situ redn. processes. The use of MG fiber provides good flexibility (114 MPa) and charge transfer enhancement (chem. mechanism, CM) for a SERS sensor and allows further in situ growth of AuNCs on its surface to build highly sensitive hot spots (electromagnetic mechanism, EM), promoting the durability and SERS performance of the substrate in complex environments. Therefore, the formed flexible MG/AuNCs-1 fiber exhibits a low detection limit of 1 x 10-11 M with a 2.01 x 109 enhancement factor (EFexp), signal repeatability (RSD = 9.80%), and time retention (remains 75% after 90 days of storage) for R6G mols. Furthermore, the L-cysteine-modified MG/AuNCs-1 fiber realized the trace and selective detection of trinitrotoluene (TNT) mols. (0.1μM) via Meisenheimer complex formation, even by sampling the TNT mols. at a fingerprint or sample bag. These findings fill the gap in the large-scale fabrication of high-performance 2D materials/precious-metal particle composite SERS substrates, with the expectation of pushing flexible SERS sensors toward wider applications.
- 179Limbu, T. B.; Chitara, B.; Orlando, J. D.; Garcia Cervantes, M. Y.; Kumari, S.; Li, Q.; Tang, Y.; Yan, F. Green synthesis of reduced Ti3C2Tx MXene nanosheets with enhanced conductivity, oxidation stability, and SERS activity. J. Mater. Chem. C 2020, 8, 4722– 4731, DOI: 10.1039/c9tc06984dGoogle Scholar179https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXksVWhurc%253D&md5=9452a49faea379301c8b1a3b01f61c45Green synthesis of reduced Ti3C2Tx MXene nanosheets with enhanced conductivity, oxidation stability, and SERS activityLimbu, Tej B.; Chitara, Basant; Orlando, Jason D.; Garcia Cervantes, Martha Y.; Kumari, Shalini; Li, Qi; Tang, Yongan; Yan, FeiJournal of Materials Chemistry C: Materials for Optical and Electronic Devices (2020), 8 (14), 4722-4731CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)Transition metal carbides (MXenes) are an emerging family of highly conductive two-dimensional materials with addnl. functional properties introduced by surface terminations. Further modification of the surface terminations makes MXenes even more appealing for practical applications. Herein, we report a facile and environmentally benign synthesis of reduced Ti3C2Tx MXene (r-Ti3C2Tx) via a simple treatment with L-ascorbic acid at room temp. r-Ti3C2Tx shows a six-fold increase in elec. cond., from 471 ± 49 for regular Ti3C2Tx to 2819 ± 306 S m-1 for the reduced version. Addnl., we show an enhanced oxidn. stability of r-Ti3C2Tx as compared to regular Ti3C2Tx. An examn. of the surface-enhanced Raman scattering (SERS) activity reveals that the SERS enhancement factor of r-Ti3C2Tx is an order of magnitude higher than that of regular Ti3C2Tx. The improved SERS activity of r-Ti3C2Tx is attributed to the charge transfer interaction between the MXene surface and probe mols., re-enforced by an increased electronic d. of states (DOS) at the Fermi level of r-Ti3C2Tx. The findings of this study suggest that reduced MXene could be a superior choice over regular MXene, esp. for the applications that employ high electronic cond., such as electrode materials for batteries and supercapacitors, photodetectors, and SERS-based sensors.
- 180Lombardi, J. R.; Birke, R. L. Theory of surface-enhanced Raman scattering in semiconductors. J. Phys. Chem. C 2014, 118, 11120– 11130, DOI: 10.1021/jp5020675Google Scholar180https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXntlKgsrk%253D&md5=b5e40ca0602dfb1ae681a1904f275759Theory of Surface-Enhanced Raman Scattering in SemiconductorsLombardi, John R.; Birke, Ronald L.Journal of Physical Chemistry C (2014), 118 (20), 11120-11130CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)An anal. expression was developed for the lowest order nonzero contribution to the SERS from a system composed of a mol. adsorbed on a semiconductor nanoparticle. A combined mol.-semiconductor system and include Herzberg-Teller vibronic coupling of the zero-order Born-Oppenheimer states are considered. This follows a previous derivation for metallic SERS, but instead of a Fermi level, the semiconductor system involves a band gap and the SERS enhancement is maximized at either the conduction or valence band edge. The resulting expression may be regarded as an extension of the Albrecht A-, B-, and C-terms and show that the SERS enhancement is caused by several resonances in the combined system, namely, surface plasmon, exciton, charge-transfer, and mol. resonances. These resonances are coupled by terms in the numerator, which provide strict selection rules that enable one to test the theory and predict the relative intensities of the Raman lines. By considering interactions of the various contributions to the SERS enhancement, ways were developed to optimize the enhancement factor by tailoring the semiconductor nanostructure thereby adjusting the location of the various contributing resonances.
- 181Kim, J.; Jang, Y.; Kim, N.-J.; Kim, H.; Yi, G.-C.; Shin, Y.; Kim, M. H.; Yoon, S. Study of Chemical Enhancement Mechanism in Non-plasmonic Surface Enhanced Raman Spectroscopy (SERS). Front. Chem. 2019, 7, 582, DOI: 10.3389/fchem.2019.00582Google Scholar181https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXmvVaqsro%253D&md5=1f6078e475b2feaa9a21b48e864204daStudy of chemical enhancement mechanism in non-plasmonic surface enhanced Raman spectroscopy (SERS)Kim, Jayeong; Jang, Yujin; Kim, Nam-Jung; Kim, Heehun; Yi, Gyu-Chul; Shin, Yukyung; Kim, Myung Hwa; Yoon, SeokhyunFrontiers in Chemistry (Lausanne, Switzerland) (2019), 7 (), 582CODEN: FCLSAA; ISSN:2296-2646. (Frontiers Media S.A.)Surface enhanced Raman spectroscopy (SERS) has been intensively investigated during the past decades for its enormous electromagnetic field enhancement near the nanoscale metallic surfaces. Chem. enhancement of SERS, however, remains rather elusive despite intensive research efforts, mainly due to the relatively complex enhancing factors and inconsistent exptl. results. To study details of chem. enhancement mechanism, we prepd. various low dimensional semiconductor substrates such as ZnO and GaN that were fabricated via metal org. chem. vapor deposition process. We used three kinds of mols. (4-MPY, 4-MBA, 4-ATP) as analytes to measure SERS spectra under non-plasmonic conditions to understand charge transfer mechanisms between a substrate and analyte mols. leading to chem. enhancement. We obsd. that there is a preferential route for charge transfer responsible for chem. enhancement, i.e., there exists a dominant enhancement process in non-plasmonic SERS. To further confirm our idea of charge transfer mechanism, we used a combination of 2-dimensional transition metal dichalcogenide substrates and analyte mols. We also obsd. significant enhancement of Raman signal from mols. adsorbed on 2-dimensional transition metal dichalcogenide surface that is completely consistent with our previous results. We also discuss crucial factors for increasing enhancement factors for chem. enhancement without involving plasmonic resonance.
- 182Kim, N.-J.; Kim, J.; Park, J.-B.; Kim, H.; Yi, G.-C.; Yoon, S. Direct observation of quantum tunnelling charge transfers between molecules and semiconductors for SERS. Nanoscale 2019, 11, 45– 49, DOI: 10.1039/C8NR08389DGoogle Scholar182https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXit12ks7%252FN&md5=a5fe08b3d2fe68a1d2b581e75ec33a83Direct observation of quantum tunnelling charge transfers between molecules and semiconductors for SERSKim, Nam-Jung; Kim, Jayeong; Park, Jun-Beom; Kim, Hyemin; Yi, Gyu-Chul; Yoon, SeokhyunNanoscale (2019), 11 (1), 45-49CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)We used high-quality ZnO nanostructures/graphene substrates for understanding the mechanisms of charge transfer (CT) that take place under nonplasmonic conditions. As the optimal conditions for CT processes are found, we studied the range of CT normal to the ZnO surface that is coated with nanoscale HfO2 layers with different thicknesses. We could observe that CT decays over a few nanometers. In addn., we also obsd. a unique oscillation of the SERS intensity in the atomically thin oxide layers, which reflects the quantum tunneling effects of CT electrons across the oxide layers. To the best of our knowledge, this is the first direct observation of SERS-active charge transport and measurement of a CT span with at.-scale accuracy.
- 183Jia, S.; Bandyopadhyay, A.; Kumar, H.; Zhang, J.; Wang, W.; Zhai, T.; Shenoy, V. B.; Lou, J. Biomolecular sensing by surface-enhanced Raman scattering of monolayer Janus transition metal dichalcogenide. Nanoscale 2020, 12, 10723– 10729, DOI: 10.1039/d0nr00300jGoogle Scholar183https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXntFyhtbY%253D&md5=77db382bd9b326ab75d19bb95097aa70Biomolecular sensing by surface-enhanced Raman scattering of monolayer Janus transition metal dichalcogenideJia, Shuai; Bandyopadhyay, Arkamita; Kumar, Hemant; Zhang, Jing; Wang, Weipeng; Zhai, Tianshu; Shenoy, Vivek B.; Lou, JunNanoscale (2020), 12 (19), 10723-10729CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)In this work, we demonstrate that monolayer Janus MoSSe is an effective and universal platform for enhancing Raman signal and detecting biomols. for the first time. The out-of-plane dipoles in monolayer Janus MoSSe redistribute charges of adsorbed biomols., polarize biomols. and enhance their Raman vibrational intensity. The estd. Raman enhancement factor is higher than 105, which is comparable with the highest reported enhancement factor for 2D substrates. The C-C stretching Raman peak around 1360 cm-1 is used to indicate the glucose concn., and its peak-integrated intensity increases linearly with the glucose concn. in the range of 1-10 mM. DFT calcns. also confirm that charge redistribution in glucose induced by dipole interactions can enhance Raman intensity significantly when glucose mols. are adsorbed onto monolayer Janus MoSSe.
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Abstract
Figure 1
Figure 1. Timeline of the crucial events contributed significantly to the advancement and realization of the SERS technique.
Figure 2
Figure 2. Schematic illustration of the EM and CE mechanism of SERS.
Figure 3
Figure 3. (A) Raman spectra of the CuPc (2 Å) molecule on the blank SiO2/Si substrate (black line), graphene (blue line), h-BN (red line), and MoS2 (green line) substrates. The numbers marked on the peaks are the peak frequencies of the Raman signals from the CuPc molecule. For all of the spectra, the baseline correction was removed to have a better comparison. (B) Optical image of a h-BN flake. Some h-BN flakes are marked by arrows or by a red dashed ring. (C) Raman mapping image for the CuPc vibrational mode at 1531 cm–1 corresponding to (B). Reprinted with permission from ref (33). Copyright 2014 American Chemical Society.
Figure 4
Figure 4. (A) Schematic illustration of synthesizing the AuNPs@MoS2 nanocomposite. TEM images of (B) MoS2 and (C–G) AuNPs@MoS2 nanocomposites. Reprinted with permission from ref (120). Copyright 2014 American Chemical Society.
Figure 5
Figure 5. (A) Schematic illustration of the CT process among S-g-C3N4, O2, and Ag. The label δ denotes the negative charge of the Ag surface or S-g-C3N4. (B) TEM image of the S-g-C3N4/Ag hybrid. (A,B) Reprinted with permission from ref (43). Copyright 2016 the author(s).
Figure 6
Figure 6. (A) Raman profile of R6G (10–6 M) on substrates deposited with an unincorporated MoS2 sample, hydrothermally treated oxygen-substituted MoS2 sample at 200 °C, partially oxidized sample at 300 °C for 40 min, completely oxidized MoO3 sample, and bare SiO2/Si. (B) Energy-level diagrams illustrating the electronic transitions. The calculated band structures of MoS2 (a) and MoSxOy (b) taking the Fermi level as a reference. Schematic energy-level diagrams of R6G on (c) MoSxOy and (d) MoS2 and MoO3 with respect to the vacuum level. (C) Raman spectra of 10–5, 10–6, 10–7, and 10–8 M RhB on PdSe2. (D) Energy band diagram showing the CT pathways in the RhB/PdSe2 hybrid system. (A,B) Reprinted with permission from ref (138). Copyright 2017 the author(s). (C,D) Reprinted with permission from ref (141). Copyright 2023 the author(s).
Figure 7
Figure 7. (A) Graphical representation of in situ one-step solution processing synthesis of Ag, Au, and Pd@MXene (Ti3C2Tx) hybrids by soft-solution processing via a sonochemical approach. (B) Raman spectrum of Ti3C2Tx after soaking in MB dispersed in ethanol and subsequent drying. SERS spectra of MB with (b) Ag@, (c) Au@, and (d) Pd@MXene. Reprinted with permission from ref (169). Copyright 2016 the author(s).
Figure 8
Figure 8. (a,b) SEM images of a Ti3AlC2 bulk structure (a) and Ti3C2 MXene (b). (c,d) TEM images, HRTEM images, and the corresponding SAED patterns (inset in the HRTEM images) of Ti3C2 MXene (c) and Au–Ti3C2 (d). (e,f) SERS spectra of 4-MBA, MeB, and MV powder; SERS spectra of the mixed solution with 10–5 M 4-MBA, MV, and MeB on Ti3C2 (e) and Au–Ti3C2 (f) substrates with different excitation lasers of 532, 633, and 785 nm. Reprinted with permission from ref (174). Copyright 2020 the author(s).
Figure 9
Figure 9. (a) SEM micrographs of the r-Ti3C2Tx powder. (b) Tapping mode AFM image of Ti3C2Tx nanosheets on SiO2/Si. (c) XRD patterns of the Ti3AlC2 MAX phase (black), Ti3C2Tx (red), and r-Ti3C2Tx (blue). SERS spectra of the probe molecules: (d) crystal violet at 2 × 10–6 M, (e) MB at 1 × 10–6 M, and (f) rhodamine 6G (R6G) at 1 × 10–7 M, respectively, collected on Ti3C2Tx/SiO2/Si (black) and r-Ti3C2Tx/SiO2/Si (red) substrates. Used with permission of The Royal Society of Chemistry, from ref (179); permission conveyed through Copyright Clearance Center, Inc.
References
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- 1Fleischmann, M.; Hendra, P. J.; McQuillan, A. J. Raman Spectra of Pyridine Adsorbed at a Silver Electrode. Chem. Phys. Lett. 1974, 26, 163– 166, DOI: 10.1016/0009-2614(74)85388-11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2cXksFKjtbo%253D&md5=4fb726391701c49ce221a597dd5e2a03Raman spectra of pyridine adsorbed at a silver electrodeFleischmann, M.; Hendra, P. J.; McQuillan, A. J.Chemical Physics Letters (1974), 26 (2), 163-6CODEN: CHPLBC; ISSN:0009-2614.Raman spectroscopy was employed for the 1st time to study the role of adsorption at electrodes. It was possible to distinguish 2 types of pyridine adsorption at a Ag electrode. The variation in intensity and frequency of some of the bands with potential in the region of the point of zero charge gave further evidence as to the structure of the elec. double layer; the interaction of adsorbed pyridine and water must be taken into account.
- 2Jeanmaire, D. L.; Van Duyne, R. P. Surface raman spectroelectrochemistry: Part I. Heterocyclic, aromatic, and aliphatic amines adsorbed on the anodized silver electrode. J. Electroanal. Chem. Interfacial Electrochem. 1977, 84, 1– 20, DOI: 10.1016/S0022-0728(77)80224-62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXmtVyntb8%253D&md5=1952c2e14e86ab63275a721db1c57db1Surface Raman spectroelectrochemistry. Part I. Heterocyclic, aromatic, and aliphatic amines adsorbed on the anodized silver electrodeJeanmaire, David L.; Van Duyne, Richard P.Journal of Electroanalytical Chemistry and Interfacial Electrochemistry (1977), 84 (1), 1-20CODEN: JEIEBC; ISSN:0022-0728.The remarkable sensitivity of Raman spectroscopy was verified for the study of adsorbed pyridine on a Ag surface, and its applicability extended to other N heterocycles and amines. New bands in the scattering spectrum of adsorbed pyridine were characterized, which were not previously reported, as well as the Raman intensity response of all the surface pyridine bands as a function of electrode potential. As a result of these expts., a model is proposed of the adsorbed species for pyridine in which the adsorption is anion induced, leading to an axial end-on attachment to the electrode surface. The ability to obtain resonance Raman spectra with good signal-to-noise ratios with laser powers < 1.0 mW, opens up possibilities of surface Raman studies with relatively inexpensive laser systems. As laser power requirements are relaxed, reliability is improved, and greater tuning ranges can be achieved for wavelength dependent studies. The potential of resonance Raman spectroscopy was previously demonstrated for monitoring soln. kinetic behavior; now it is shown that normal Raman as well as resonance Raman spectroscopy have sufficient sensitivity to extend the studies of kinetic processes to include those occurring at electrode surfaces.
- 3Albrecht, M. G.; Creighton, J. A. Anomalously Intense Raman Spectra of Pyridine at a Silver Electrode. J. Am. Chem. Soc. 1977, 99, 5215– 5217, DOI: 10.1021/ja00457a0713https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE2sXkslKjsb4%253D&md5=94e6c8e0977783c4d4ef4fa778a6d683Anomalously intense Raman spectra of pyridine at a silver electrodeAlbrecht, M. Grant; Creighton, J. AlanJournal of the American Chemical Society (1977), 99 (15), 5215-17CODEN: JACSAT; ISSN:0002-7863.Raman bands due to pyridine absorbed at a Ag electrode, which are absent for a freshly cleaned electrode immersed in aq. pyridine/KCl, are anomalously intense after a single electrochem. roughening cycle. The intensity enhancement is estd. to be ∼105-fold, and is possibly due to a resonance Raman effect in pyridine induced by an electronic interaction with the roughened metal surface. The high intensity of Raman bands enables changes in the surface concn. of absorbed pyridine to be readily followed during and after the roughening cycle.
- 4Moskovits, M. Surface Roughness and the Enhanced Intensity of Raman Scattering by Molecules Adsorbed on Metals. J. Chem. Phys. 1978, 69, 4159– 4161, DOI: 10.1063/1.4370954https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXht1OhtQ%253D%253D&md5=16d496023b0831f1c07a9f83fb7f80ffSurface roughness and the enhanced intensity of Raman scattering by molecules adsorbed on metalsMoskovits, M.Journal of Chemical Physics (1978), 69 (9), 4159-61CODEN: JCPSA6; ISSN:0021-9606.It is proposed that the anomalous intensity arises from preresonant or resonant excitations of conduction electron resonances in adsorbate covered metal bumps on the surface. The bumps form a 2-dimensional colloidlike layer which displays a collective resonance at a frequency which depends on the bump d. The model can account for the disparate excitation functions reported in terms of varying degrees of roughness. The apparent lack of enhancement with metals other than Group IB is also explained.
- 5Stiles, P. L.; Dieringer, J. A.; Shah, N. C.; Van Duyne, R. P. Surface-enhanced Raman spectroscopy. Annu. Rev. Anal. Chem. 2008, 1, 601– 626, DOI: 10.1146/annurev.anchem.1.031207.1128145https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhtFygsLzJ&md5=993c957096ba93ca702d7b754cae7d7fSurface-enhanced Raman spectroscopyStiles, Paul L.; Dieringer, Jon A.; Shah, Nilam C.; Van Duyne, Richard P.Annual Review of Analytical Chemistry (2008), 1 (), 601-626CODEN: ARACFU; ISSN:1936-1327. (Annual Reviews Inc.)A review. The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon resonance of a nanostructured surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon to a rapidly developing anal. tool. This article first explains many fundamental features of SERS and then describes the use of nanosphere lithog. for the fabrication of highly reproducible and robust SERS substrates. In particular, we review metal film over nanosphere surfaces as excellent candidates for several expts. that were once impossible with more primitive SERS substrates (e.g., metal island films). The article also describes progress in applying SERS to the detection of chem. warfare agents and several biol. mols.
- 6Baik, S. Y.; Cho, Y. J.; Lim, Y. R.; Im, H. S.; Jang, D. M.; Myung, Y.; Park, J.; Kang, H. S. Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell Nanowires. ACS Nano 2012, 6, 2459– 2470, DOI: 10.1021/nn204797b6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhvFahtbY%253D&md5=df0dd1abe969498ebb7599a4a1705ca3Charge-Selective Surface-Enhanced Raman Scattering Using Silver and Gold Nanoparticles Deposited on Silicon-Carbon Core-Shell NanowiresBaik, Sun Young; Cho, Yong Jae; Lim, Young Rok; Im, Hyung Soon; Jang, Dong Myung; Myung, Yoon; Park, Jeunghee; Kang, Hong SeokACS Nano (2012), 6 (3), 2459-2470CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The deposition of silver (Ag) or gold (Au) nanoparticles (NPs) on vertically aligned silicon-carbon (Si-C) core-shell nanowires (NWs) produces sensitive substrates for surface-enhanced Raman spectroscopy (SERS). The undoped and 30% nitrogen (N)-doped graphitic layers of the C shell (avg thickness of 20 nm) induce a higher sensitivity toward neg. (-) and pos. ( + ) charged dye mols., resp., showing remarkable charge selectivity. The Ag NPs exhibit higher charge selectivity than the Au NPs. The Ag NPs deposited on p- and n-type Si NWs also exhibit (-) and ( + ) charge selectivity, resp., which is higher than that of the Au NPs. The XPS anal. indicates that the N-doped graphitic layers donate more electrons to the metal NPs than the undoped ones. More distinct electron transfer occurs to the Ag NPs than to the Au NPs. First principles calcns. of the graphene-metal adducts suggest that the large electron transfer capacity of the N-doped graphitic layers is due to the formation of a N→Ag coordinate bond involving the lone pair electrons of the N atoms. Probably the more (-) charged NPs on the N-doped graphitic layers prefer the adsorption of ( + ) charged dyes, enhancing the SERS intensity. The charge selectivity of the Si NW substrates can also be rationalized by the greater electron transfer from the n-type Si to the metal NPs.
- 7Liu, D.; Zhou, F.; Li, C.; Zhang, T.; Zhang, H.; Cai, W.; Li, Y. Black Gold: Plasmonic colloidosomes with broadband absorption self-assembled from monodispersed gold nanospheres by using a reverse emulsion system. Angew. Chem., Int. Ed. 2015, 54, 9596– 9600, DOI: 10.1002/anie.2015033847https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVKmsL7O&md5=2d5cf6067b1223e3c5801cd79ef24ad1Black Gold: Plasmonic Colloidosomes with Broadband Absorption Self-Assembled from Monodispersed Gold Nanospheres by Using a Reverse Emulsion SystemLiu, Dilong; Zhou, Fei; Li, Cuncheng; Zhang, Tao; Zhang, Honghua; Cai, Weiping; Li, YueAngewandte Chemie, International Edition (2015), 54 (33), 9596-9600CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A facile approach for the fabrication of black plasmonic colloidosomes assembled from Au nanospheres is developed by an emulsion-templating strategy. This self-assembly process is based on a reverse water-in-1-butanol emulsion system, in which the water emulsion droplets can dissolve into 1-butanol (oil) phase at an appropriate rate. These Au colloidosomes possess hcp. multilayer shells and show a low reflectivity and intense broadband absorption owing to the strong interparticle plasmonic coupling, which is further investigated by a finite-difference time-domain method. This method is universal and is suitable for self-assembly of different noble-metal nanoparticles into different colloidosomes.
- 8Otto, A. The ‘chemical’ (electronic) contribution to surface-enhanced Raman scattering. J. Raman Spectrosc. 2005, 36, 497– 509, DOI: 10.1002/jrs.13558https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXntVansLw%253D&md5=03c548c51d30907fd154f651b3194a55The 'chemical' (electronic) contribution to surface-enhanced Raman scatteringOtto, AndreasJournal of Raman Spectroscopy (2005), 36 (6/7), 497-509CODEN: JRSPAF; ISSN:0377-0486. (John Wiley & Sons Ltd.)The model of surface-enhanced Raman scattering (SERS) by time-dependent evolution in the intermediate anionic state of the adsorbate is analogous to intramol. Franck-Condon resonance Raman scattering. For adsorbates with a π* state, the residence time of some femtoseconds (10-15 s) in the anionic state leads to a sepn. of electron (e) and hole (h), which quenches SERS at a smooth surface. At so-called SERS-active sites, the residence time of the hole is enhanced, and there is no final e-h pair and the excitation of only a mol. vibration leads to SERS. But for mols. with only high-energy σ* states, the residence time in the anionic state is <1 fs (analogous to the impulse mechanism in electron scattering), and the creation of e-h pairs is less likely. This leads to 1st-layer electronic Raman scattering, esp. by C-H stretch vibrations with an av. enhancement of ∼30-40-fold.
- 9Persson, B. N. J.; Zhao, K.; Zhang, Z. Y. Chemical contribution to surface-enhanced Raman scattering. Phys. Rev. Lett. 2006, 96, 207401, DOI: 10.1103/PhysRevLett.96.2074019https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XltVOju7Y%253D&md5=579010b2a2a7c89e007cf16b053d0c60Chemical Contribution to Surface-Enhanced Raman ScatteringPersson, B. N. J.; Zhao, Ke; Zhang, ZhenyuPhysical Review Letters (2006), 96 (20), 207401/1-207401/4CODEN: PRLTAO; ISSN:0031-9007. (American Physical Society)We present a new mechanism for the chem. contribution to surface-enhanced Raman scattering (SERS). The theory considers the modulation of the polarizability of a metal nanocluster or a flat metal surface by the vibrational motion of an adsorbed mol. The modulated polarization of the substrate coupled with the incident light will contribute to the Raman scattering enhancement. We show that for a metal cluster and for a flat metal surface this new chem. contribution may enhance the Raman scattering intensity by a factor of ∼102 and ∼104, resp. The new SERS process is detd. by the elec. field parallel to the surface of the metal substrate at the mol. binding site.
- 10Morton, S. M.; Jensen, L. Understanding the Molecule–Surface Chemical Coupling in SERS. J. Am. Chem. Soc. 2009, 131 (11), 4090– 4098, DOI: 10.1021/ja809143c10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXisFamtLw%253D&md5=6feb18059f8e9abdb86ff2150d420cdbUnderstanding the Molecule-Surface Chemical Coupling in SERSMorton, Seth M.; Jensen, LasseJournal of the American Chemical Society (2009), 131 (11), 4090-4098CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The enhancement mechanism due to the mol.-surface chem. coupling in surface-enhanced Raman scattering (SERS) was characterized using time-dependent d. functional theory. This was achieved with a systematical study of the chem. enhancement of meta- and para-substituted pyridines interacting with a small silver cluster (Ag20). Changing the functional groups on pyridine enabled one to modulate the direct chem. interactions between the pyridine ring and the metal cluster. Surprisingly, the enhancement does not increase as more charge is transferred from the pyridine ring to the cluster. Instead, the magnitude of chem. enhancement is governed to a large extent by the energy difference between the highest occupied energy level (HOMO) of the metal and the lowest unoccupied energy level (LUMO) of the mol. The enhancement scales roughly as (ωX/‾ωe)4, where ‾ωe is an av. excitation energy between the HOMO of the metal and the LUMO of the mol. and ωX is the HOMO-LUMO gap of the free mol. The trend was verified by considering substituted benzenethiols, small mols., and silver clusters of varying sizes. The results imply that mols. that show significant stabilization of the HOMO-LUMO gaps (such as those that readily accept π-backbonding) would be likely to have strong chem. enhancement. The findings presented here provide the framework for designing new mols. which exhibit high chem. enhancements. However, it remains a challenge to accurately describe the magnitude of the Raman enhancements using electronic structure methods, esp. d. functional theory, because they often underestimate the energy gap.
- 11Creighton, J. A.; Blatchford, C. G.; Albrecht, M. G. Plasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelength. J. Chem. Soc., Faraday Trans. 2 1979, 75, 790– 798, DOI: 10.1039/f2979750079011https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE1MXlsFKrtLk%253D&md5=06880d68306c8b44a81ccd60896898ebPlasma resonance enhancement of Raman scattering by pyridine adsorbed on silver or gold sol particles of size comparable to the excitation wavelengthCreighton, J. Alan; Blatchford, Christopher G.; Albrecht, M. GrantJournal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics (1979), 75 (5), 790-8CODEN: JCFTBS; ISSN:0300-9238.The enhancement of the Raman-scattering intensity of pyridine mols. adsorbed on Ag or Au sols. of particle size similar to the excitation wavelength was examd. The degree of enhancement was greatest for excitation at the wavelength of the Mie extinction max. of the metal particles. A new resonance-Raman phenomenon is proposed in which the polarizability of the metal particles is modulated by vibrations of adsorbed mols. Surface plasma oscillations are involved in the intense Raman scattering by metals adsorbed on rough Ag surfaces. The metal dielec.-function requirements for resonant Mie scattering enable the excitation wavelength for plasma-resonance enhancement of Raman scattering by mols. adsorbed on other metals to be estd.
- 12Hildebrandt, P.; Stockburger, M. Surface-Enhanced Resonance Raman Spectroscopy of Rhodamine 6G Adsorbed on Colloidal Silver. J. Phys. Chem. 1984, 88, 5935– 5944, DOI: 10.1021/j150668a03812https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaL2cXmtFyrsr8%253D&md5=c4629b5f47502c5374d8430ff211a61eSurface-enhanced resonance Raman spectroscopy of Rhodamine 6G adsorbed on colloidal silverHildebrandt, Peter; Stockburger, ManfredJournal of Physical Chemistry (1984), 88 (24), 5935-44CODEN: JPCHAX; ISSN:0022-3654.Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal Ag was studied. Adsorption isotherms could be obtained from SERRS and fluorescent measurements. Two different kinds of adsorption sites were inferred from the isotherms. One kind is rather unspecific and shows a high surface coverage. The enhancement factor at such sites is 3000, which can be well explained by the classical electromagnetic theory of colloids. The 2nd kind is only obsd. in the presence of anions (Cl-, I-, Br-, F-, SO42-). Specific active sites are formed at an extremely low surface coverage. From the isotherms at such sites the mols. are chemisorbed. Overall enhancement factors up to 106 were found for mols. at anion-activated sites. The addnl. enhancement factor is ascribed to a local mechanism of an R6G-adatom (or cluster)-anion surface complex. SERRS excitation profiles of active sites are closely related to the mol. resonance at 530 nm. SERRS spectra of R6G were recorded and analyzed in a wide frequency range. The 2 adsorption sites could be distinguished by characteristic vibrational features. It was demonstrated that SERRS is also a powerful anal. tool for dye mols.
- 13Michaels, A. M.; Nirmal, M.; Brus, L. Surface enhanced Raman spectroscopy of individual Rhodamine 6G molecules on large Ag nanocrystals. J. Am. Chem. Soc. 1999, 121 (43), 9932– 9939, DOI: 10.1021/ja992128q13https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXmsFejs7c%253D&md5=e50bc2e15f5de8b3d2807e776092dfccSurface Enhanced Raman Spectroscopy of Individual Rhodamine 6G Molecules on Large Ag NanocrystalsMichaels, Amy M.; Nirmal, M.; Brus, L. E.Journal of the American Chemical Society (1999), 121 (43), 9932-9939CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)To explore the relation between local electromagnetic field enhancement and the large SERS (surface enhanced Raman scattering) enhancement that enables the observation of single mol. Raman spectra, the authors measure both resonant Rayleigh scattering spectra and rhodamine 6G Raman spectra from single Ag particles. The authors' app. combines the techniques of dark-field optical microscopy for resonant Rayleigh measurements, and grazing incidence Raman spectroscopy. The Rayleigh spectra show that the citrate-reduced Ag colloid is extremely heterogeneous. Only the larger particles, in part created by salt induced aggregation, show a large SERS effect. In agreement with the work of Nie and Emory, a few nanocrystals show huge single mol. R6G SERS intensities. While all SERS active particles have some resonant Rayleigh scattering at the 514.5 nm laser wavelength, there is no correlation between the resonant Rayleigh spectra and the SERS intensity. The authors discuss a model in which huge SERS intensities result from single chemisorbed mols. interacting with ballistic electrons in optically excited large Ag particles. This model is a natural consequence of the std. local electromagnetic field model for SERS and the high surface sensitivity of plasmon dephasing in the noble metals.
- 14Yang, Y.; Li, Z. Y.; Yamaguchi, K.; Tanemura, M.; Huang, Z. R.; Jiang, D.; Chen, Y.; Zhou, F.; Nogami, M. Controlled fabrication of silver nanoneedles array for SERS and their application in rapid detection of narcotics. Nanoscale 2012, 4 (8), 2663– 2669, DOI: 10.1039/c2nr12110gThere is no corresponding record for this reference.
- 15Guselnikova, O.; Nugraha, A. S.; Na, J.; Postnikov, P.; Kim, H.-J.; Plotnikov, E.; Yamauchi, Y. Surface Filtration in Mesoporous Au Films Decorated by Ag Nanoparticles for Solving SERS Sensing Small Molecules in Living Cells. ACS Appl. Mater. Interfaces 2022, 14 (36), 41629– 41639, DOI: 10.1021/acsami.2c1280415https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xit1Kjs7nI&md5=5a83f2eedadeb4912b43ce69a42a4471Surface Filtration in Mesoporous Au Films Decorated by Ag Nanoparticles for Solving SERS Sensing Small Molecules in Living CellsGuselnikova, Olga; Nugraha, Asep Sugih; Na, Jongbeom; Postnikov, Pavel; Kim, Hyun-Jong; Plotnikov, Evgenii; Yamauchi, YusukeACS Applied Materials & Interfaces (2022), 14 (36), 41629-41639CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)For surface-enhanced Raman spectroscopy (SERS) sensing of small mols. in the presence of living cells, biofouling and blocking of plasmonic centers are key challenges. Here, we have developed a mesoporous Au (AuM) film coated with a Ag nanoparticles (NPs) as a plasmonic sensor (AuM@Ag) to analyze arom. thiols, which is an example of a small mol., in the presence of a living cell strain (e.g., MDA-MB-231) as a model living system. The resulting AuM@Ag provides 0.1 nM sensitivity and high reproducibility for thiols sensing. Simultaneously, the AuM@Ag film filters large biomols., preventing Raman signals from overlapping produced by large biomols. After anal., the AuM@Ag film undergoes recycling by the full dissoln. of the Ag-thiol layer and removal of thiols from AuM. Furthermore, fresh AgNPs are formed for further SERS anal., which circumvents the Ag oxidn. issue. The ease of the AgNPs deposition allows up to 12 cycles of on-demand recycling and sensing even after utilization as a sensor in multicomponent media without enhancement and sensitivity loss. The reported mesoporous film with surface filtering ability and prominent recycling procedure promises to offer a new strategy for the detection of various small mols. in the presence of living cells.
- 16Yao, X.; Jiang, S.; Luo, S.; Liu, B. W.; Huang, T. X.; Hu, S.; Zhu, J.; Wang, X.; Ren, B. Uniform Periodic Bowtie SERS Substrate with Narrow Nanogaps Obtained by Monitored Pulsed Electrodeposition. ACS Appl. Mater. Interfaces 2020, 12 (32), 36505– 36512, DOI: 10.1021/acsami.0c0935716https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsVSmsL3J&md5=d4f438d0d8c87955f02b0f8b17f074cdUniform Periodic Bowtie SERS Substrate with Narrow Nanogaps Obtained by Monitored Pulsed ElectrodepositionYao, Xu; Jiang, Shan; Luo, Songsong; Liu, Bo-Wen; Huang, Teng-Xiang; Hu, Shu; Zhu, Jinfeng; Wang, Xiang; Ren, BinACS Applied Materials & Interfaces (2020), 12 (32), 36505-36512CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive technique with mol. specificity, making it an ideal anal. tool in various fields. However, the breadth of practical applications of SERS has been severely limited because it is still a great challenge to achieve simultaneously a high sensitivity and a high reproducibility. Herein, we report a highly controllable method to fabricate periodic bowtie SERS substrates with a narrow nanogap, high SERS enhancement, and good uniformity over a large area. The periodic bowtie template is first fabricated over a gold film by holog. lithog. (HL), followed by Au deposition to obtain a conductive plasmonic bowtie array. The gap size is then narrowed down by pulsed electrodeposition of Ag simultaneously monitored in situ by electrochem. dark field spectroscopy. Thus, we are able to observe the most sensitive change in the scattering spectra when the gap is just about to merge and obtain uniform SERS substrates with a gap size down to around 5 nm. The av. enhancement factor of 5 x 107 to 1 x 108 is obtained, which is 50 times larger than that from Au nanoparticle-assembled substrates and 140 times larger than that from com. Klarite chips. This substrate offers a promising opportunity for SERS practical applications.
- 17Nie, S.; Emory, S. R. Probing single molecules and single nanoparticles by surface-enhanced Raman scattering. Science 1997, 275 (5303), 1102– 1106, DOI: 10.1126/science.275.5303.110217https://chemport.cas.org/serviceProbing single molecules and single nanoparticles by surface-enhanced Raman scatteringNie, Shuming; Emory, Steven R.Science (Washington, D. C.) (1997), 275 (5303), 1102-1106CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)Optical detection and spectroscopy of single mols. and single nanoparticles were achieved at room temp. using surface-enhanced Raman scattering. Individual Ag colloidal nanoparticles were screened from a large heterogeneous population for special size-dependent properties and were then used to amplify the speculation for special size-dependent properties and were then used to amplify the spectroscopic signatures of adsorbed mols. For single rhodamine 6G mols. adsorbed on the selected nanoparticles, the intrinsic Raman enhancement factors were ∼1014 to 1015, much larger than the ensemble-averaged values derived from conventional measurements. This enormous enhancement leads to vibrational Raman signals that are more intense and more stable than single-mol. fluorescence.