Effective tuning and application of graphene-based Au nanocomposites as SERS substrates

Graphene-based noble metal nanocomposites have attracted tremendous research interest in the fields of surface-enhanced Raman scattering (SERS) recently. However, efficient utilization as SERS substrates has been impeded by the difficulty of tuning SERS enhancement effects induced from chemical and plasmonic enhancement by different preparation methods of graphene. Herein, three kinds of graphene-based Au hybrid, CVD-G/Au, GO/Au and rGO/Au, which were synthesized by physical sputtering and chemical in-situ crystallization growth methods, were fabricated to evaluate as SERS substrates. Simple methods were developed to enhance the Raman signals effectively by tuning both plasmonic and chemical enhancement, respectively. Besides, the prepared rGO/Au nanocomposites were used as SERS substrates to monitor the process of plasmon-driven surface-catalyzed reaction from 4-nitrobenzenethiol (4-NBT) to p,p'-dimercaptoazobenzene (DMAB). According to systematic comparisons during power- and time-dependent SERS experiments, rGO/Au was demonstrated to be with lower power threshold and higher catalytic efficiency than Au nanoparticles (NPs) toward the reaction, which provide clues to understand the interaction between metal and graphene as well as further study of plasmon-driven chemical reactions for further.