Strong Dependence of Surface Enhanced Raman Scattering on Structure of Graphene Oxide Film.

Ling Wang,Yongqiang Yang,Yan Zhang,Jing Zhang

doi:10.3390/ma11071199

Abstract

Graphene and its derivatives have been demonstrated to be good surface-enhanced Raman scattering (SERS) substrates. However, the literature offers some contrasting views on the SERS effect of graphene-based materials. Thus, understanding the mechanism of the SERS enhancement of graphene is essential for exploring its application as a SERS substrate. In this study, graphene oxide (GO) and chemically reduced graphene oxide (CRGO) films with different morphologies and structures were prepared and applied as SERS substrates to detect Raman dye molecules. The observed enhancement factors can be as large as 10~103. The mechanism of SERS enhancement is discussed. It is shown that the SERS effect was independent of the adsorption of dye molecules and the surface morphologies of graphene-based films. Raman shifts are observed and are almost the same on different graphene-based films, indicating the existence of charge transfer between dye molecules and substrates. The Raman enhancement factors and sensitivities of dye molecules on different films are consistently within the IG/ID ratios of graphene-based substrates, indicating that the dramatically enhanced Raman spectra on graphene-based films are strongly dependent on the average size of sp2 carbon domain.

Highlights

Surface-enhanced Raman scattering (SERS) is a highly selective, sensitive, and harmless spectroscopic technique to detect molecules, which is widely used in bio-sensing, medical diagnosis, environmental testing and other areas [1,2,3,4,5,6]
Compared with a monolayer or few-layer graphene and GO, Zhang et al demonstrated that a reduced graphene oxide paper-like film with controllable shapes and a convenient manipulation was a good substrate for surface-enhanced Raman scattering (SERS) detection [24]
By using rhodamine 6G (R6G), malachite green (MG), and crystal violet (CV) as Raman probes, we systematically investigate the SERS effect of GO and chemically reduced graphene oxide (CRGO) films

Summary

Introduction

Surface-enhanced Raman scattering (SERS) is a highly selective, sensitive, and harmless spectroscopic technique to detect molecules, which is widely used in bio-sensing, medical diagnosis, environmental testing and other areas [1,2,3,4,5,6]. Compared with a monolayer or few-layer graphene and GO, Zhang et al demonstrated that a reduced graphene oxide paper-like film with controllable shapes and a convenient manipulation was a good substrate for SERS detection [24]. By using rhodamine 6G (R6G), malachite green (MG), and crystal violet (CV) as Raman probes, we systematically investigate the SERS effect of GO and CRGO films In combination with those results, we suggested that the size of each sp domain and oxygen-containing groups in graphene are responsible for the large Raman signal enhancement. Raman dye molecules, which shows great potential in bio-sensing, medical diagnosis, environmental testing and other areas

Materials

Preparation of GO Films and CRGO Films

SERS Detection

Characterization

Discussion

Conclusions