Highly Intensified Surface Enhanced Raman Scattering by Using Monolayer Graphene as the Nanospacer of Metal Film–Metal Nanoparticle Coupling System

Li, Tongtong; Choy, Wallace C. H.; Ren, Xingang; Zhang, Di; Lu, Haifei

doi:10.1002/adfm.201303384

Cited by 177 publications

(144 citation statements)

References 65 publications

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“…While complex and laborious procedures are needed for coupling graphene to nanostructured surfaces, 7,8,17 GO coating can be simply obtained by physisorption of GO sheets in…”

Section: ■ Introductionmentioning

confidence: 99%

“…While complex and laborious procedures are needed for coupling graphene to nanostructured surfaces, 7,8,17 GO coating can be simply obtained by physisorption of GO sheets in aqueous solution. 18−21 Beside obvious advantages of this approach, a detailed investigation on how the assembly of GO should be conducted to control adsorption geometry and optical properties at the interface is still lacking.…”

Section: ■ Introductionmentioning

confidence: 99%

“…13−15 Recent findings also sustained the convenient use of GO and of mild reduced GO in generating SERS signals that accurately resemble the native spectrum of the molecules in solution without frequency shifts, which instead are typically generated as a consequence of the interaction with graphene or metal. 16 Overall, veiling plasmonic nanoparticles with GO sheets is perceived as a favorite strategy to fabricate advanced SERS substrates which hold the promise of improved sensitivity, signal stability, and reproducibility.While complex and laborious procedures are needed for coupling graphene to nanostructured surfaces, 7,8,17 GO coating can be simply obtained by physisorption of GO sheets in …”

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confidence: 99%

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Controlled Veiling of Silver Nanocubes with Graphene Oxide for Improved Surface-Enhanced Raman Scattering Detection

Banchelli

Tiribilli

Angelis

et al. 2016

ACS Appl. Mater. Interfaces

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Hybrid graphene oxide (GO)/metal nanocomposites have been recently proposed as novel surface-enhanced Raman scattering (SERS) substrates. Despite an increasing interest in these systems, standardization in their fabrication process is still lacking but urgently required to support their use for real-life applications. In this work we investigate how the assembly of GO should be conducted to control adsorption geometry and optical properties at the interface with plasmonic nanostructures as monolayer assemblies of silver nanocubes, by tuning main experimental parameters including GO concentration and self-assembly time. We finally identified the experimental conditions for building up a close-fitting soft dressing of the plasmonic surface, which shows optimal characteristics for flexible and reliable SERS detection. KEYWORDS: plasmonic nanoparticles, sensing, self-assembly, Raman spectroscopy, quartz crystal microbalance ■ INTRODUCTIONSurface-enhanced Raman scattering (SERS) spectroscopy is as a robust and versatile analytical technique with the ability to offer detailed and label-free chemical information with molecular selectivity and ultrasensitivity. 1−5 The SERS effect relies on huge electromagnetic fields concentrated at the metal surface of a plasmonic nanostructure, which dramatically enhance the Raman signal of molecules placed in its close proximity. In this respect, efficient SERS enhancements are typically generated within less than 10 nm from the metal surface and are mostly confined within the so-called "hot spots", i.e. highly curved nanoregions or gaps and junctions between adjacent nanoparticles. The ability to gather molecules in these regions in a homogeneous and reproducible manner represents a current impediment that is still preventing further diffusion of SERS as a systematic analytical tool.A recent trend toward upgrading the performance of SERS technology relies on the combination of plasmonic nanostructures made of silver and gold with graphene. 6−9 Graphene is a single-atom-thick sheet of sp 2 -hybridized carbon atoms arranged in a honeycomb lattice. A number of unique chemical, electronic, optical, and structural properties make this material a preferred choice for greatly improving electronic and photonic devices. 10,11 With a focus on SERS, current efforts are taking advantage of a thin graphene coating in drawing and concentrating target molecules as well as in conferring the plasmonic surface with a passivating layer that discards possible disturbances and signal variability induced by metal−molecule interactions. 12 Main fabrication methods of graphene sheets include mechanical peel-off, epitaxial growth, and chemical vapor deposition (CVD), which, however, appear unsuitable for large-scale production of graphene, ultimately limiting its practical application. A convenient alternative is now represented by graphene oxide (GO), which is derived by oxidation of graphite in the form of graphene sheets with abundant oxygen-containing functionalities. These confer chemical st...

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“…While complex and laborious procedures are needed for coupling graphene to nanostructured surfaces, 7,8,17 GO coating can be simply obtained by physisorption of GO sheets in…”

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Controlled Veiling of Silver Nanocubes with Graphene Oxide for Improved Surface-Enhanced Raman Scattering Detection

Banchelli

Tiribilli

Angelis

et al. 2016

ACS Appl. Mater. Interfaces

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“…[1,2] In particular, the approach is extremely important for the chemically functionalized graphene samples because it allows to identify the functional groups on the graphene surface. [3] However, it is also known that graphene may strongly interact with the metals, and this interaction is also mirrored in the Raman spectra.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, many groups focused on in-deep understanding of the effect inspecting various scenarios. [2,13] For example, Sun et al proposed that a large SERS enhancement is a joint effect of the charge transfer and electromagnetic coupling, which is closely correlated with the near-field plasmon coupling of Ag nanoparticles in contact with the graphene bilayer. [14] He et al studied the Raman signal enhancement using Au nanorods [15] and concluded that when the resonant wavelength of the Au nanorods matches well with excitation laser wavelength, the Raman enhancement factor is highest up to 1,000-fold.…”

Section: Introductionmentioning

confidence: 99%

Surface‐enhanced Raman spectra on graphene

Weis

Vejpravová

Verhagen

et al. 2017

J Raman Spectroscopy

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Surface-enhanced Raman spectroscopy is a valuable tool for inspection of trace concentrations of various molecules; hence, this method has a great potential for characterization of functionalised graphene. However, to make this method a reliable analytical tool, the influence of the metal-graphene interactions on Raman spectra of the graphene must be understood. Here, the surface-enhanced Raman spectra of exfoliated single-layer graphene covered with gold or silver thin layers were studied. The metal-graphene interactions resulted in the broadening of the G mode and the 2D mode of graphene. A change of the 2D mode dispersion was also observed. The effects were found to be weaker for the silver layer; however, the Raman signal enhancement of the graphene features was found to be significantly stronger in case of the silver layer. Various scenarios of the observed effects are discussed: graphene-plasmon interaction, charge transfer between the metal and graphene, and selective enhancement at the lattice and topographic defects. Copyright © 2017 John Wiley & Sons, Ltd.Keywords: charge transfer; graphene; graphene-plasmon interaction; metal-graphene interaction; SERS IntroductionMetals such as gold and silver are known to strongly enhance the Raman signal of pristine graphene. [1,2] In particular, the approach is extremely important for the chemically functionalized graphene samples because it allows to identify the functional groups on the graphene surface. [3] However, it is also known that graphene may strongly interact with the metals, and this interaction is also mirrored in the Raman spectra. [4] Consequently, it is important to follow these effects.Raman spectra of a pristine graphene typically consist of the G mode, which appears at about 1,580 cm −1 , and the 2D mode, which is significantly dispersive and its wavenumber increases with the laser excitation energy. The dispersion comes from the slope of the Dirac cone; therefore, changes in the dispersion reflect changes in the electronic structure of the graphene. [5,6] In case that structural imperfections are present in a graphene sample, one can also observe the defect scattering related D and D' modes at around 1,350 and 1,620 cm −1 , respectively. As reported by several authors previously, the enhancement of a particular Raman mode of graphene depends on the excitation energy of the laser and plasmonic characteristics of the metallic structure in contact with the graphene, and consequently, the enhancement factors for the D, D', G, and 2D modes can be very different. [7,8] Moreover, not only the kind of metal but also the shape, dimensions, and mutual geometry of the metallic structure and graphene are of utmost importance.In a typical experiment, the enhancement of the Raman signal can be achieved by deposition of a thin layer of silver or gold or their nanoparticles over the graphene. This geometry, however, reduces intensity of the incoming light, and also, the scattered light is partly absorbed by the metal. Another option is to intercalate metal un...

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Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

Lee

Kim

Jang

et al. 2016

Adv Funct Materials

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The plasmonic coupling, the enhanced electromagnetic field occurring through a uniform and small separation between metallic particles, is required for better application to localized surface plasmon resonance. Graphene has been studied as a good spacer candidate because of its precise controllability at subnanoscale. Here, the enhancement of plasmonic coupling among metallic nanoparticles (NPs) uniformly spread out on both sides of a graphene spacer is experimentally and simulatively investigated. Additionally, the post‐evaporated flat structure is rippled along one direction to reduce the separation between nanoparticles. As the amount of rippling increases, the enhancement factor (EF) of the plasmonic coupling increases almost linearly or quadratically depending on the size of nanoparticles. Such a highly rippled nanostructure is believed to not only increase the plasmonic coupling in either side of the spacer but lead to a higher density of “hot spots” through the spacer gap also. The observed EFs of a structure with the MLG spacer are consistent with the simulation results obtained from the classical electrodynamics. On the other hand, the SLG case appears to be inconsistent with such a classical approach, indicating that the plasmon tunneling through the thin barrier is prevalent in the case of the SLG spacer.

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Highly Intensified Surface Enhanced Raman Scattering by Using Monolayer Graphene as the Nanospacer of Metal Film–Metal Nanoparticle Coupling System

Cited by 177 publications

References 65 publications

Controlled Veiling of Silver Nanocubes with Graphene Oxide for Improved Surface-Enhanced Raman Scattering Detection

Controlled Veiling of Silver Nanocubes with Graphene Oxide for Improved Surface-Enhanced Raman Scattering Detection

Surface‐enhanced Raman spectra on graphene

Multilayer Graphene with a Rippled Structure as a Spacer for Improving Plasmonic Coupling

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