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

Abstract

It is widely accepted that surface enhanced Raman scattering (SERS) enhancement results from a combination of electromagnetic mechanisms (EM) and chemical mechanisms (CM). Recently, the nanoparticle-fi lm gap (NFG) system was studied due to its strong local enhancement fi eld. However, there are still some technical limitations in establishing effective and simple ways for reliable and precise control of sub-nanospacer. In addition, works on designing the nanospacer in NFG system for effi cient interaction with target molecules for further improving SERS signals are rather limited. Here, a novel NFG system is proposed by introducing ultrathin monolayer graphene as well-defi ned subnanospacer between Ag NPs and Ag fi lm (named G(graphene)-NFG system). The new G-NFG system offers tremendous near-fi eld enhancement with one of the highest enhancement ratio of 1700 reported to date. These results show that the single-layer graphene as a sub-nanospacer renders the proposed G-NFG system with particularly strong EM enhancement (due to multiple couplings including the NP-NP couplings and NP-fi lm couplings) and additional CM enhancement in detecting some π-conjugated molecules to function as a powerful tool in analytical science and the related fi elds.

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

“…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…”

“…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.…”

“…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 …”

Surface‐enhanced Raman spectra on 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.…”

“…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.…”