The effect of graphene on surface plasmon resonance of metal nanoparticles

Abstract

Two transparent graphene-metal nanoparticle (NP) hybrid schemes, namely Au NPs covered by graphene layers and Au NPs encapsulated by graphene layers, are presented and the effect of graphene on the localized surface plasmon resonance of metal NPs is systematically investigated. For both schemes, the direct contact of graphene with Au NPs would strongly tune the resonant frequency due to the electron transfer from Au NPs to graphene. Such electron transfer is demonstrated by comparing the absorption spectra of Au NPs with different free electron densities between calculation results via FDTD simulation and experimental results, comparing Raman properties of graphene between pure graphene and the Au-NP/graphene hybrid nanostructure, correlating the electron doping concentration in graphene with the electron density change in Au NPs, and ruling out the possible mechanism of the change of the effective refractive index of Au NPs. Such an effective tuning of the resonant frequency may shed light on the future applications of 2D based materials in plasmonic devices.