Photoelectrochemical response of Ag-graphene heterostructures: Insight into localized surface plasmon enhanced photocurrent generation process.

We present Ag-graphene heterostructures by combining few layer graphene (FLG) with plasmonic silver nanoparticle (AgNP) arrays to boost the photoelectrochemical (PEC) efficiency of graphene-based nanostructures. AgNP arrays with controlled coverage and size distribution were fabricated on the graphene surface by means of gas phase cluster beam deposition. The photocurrent generation process in the FLG-based nanostructures was analyzed with a PEC amperometric measurement. A significant photocurrent enhancement was observed in the AgNPs-FLG heterostructures compared with bare FLG. It was found that the PEC performance was strongly related to the wavelength and power of the incident light, as well as the density and size of the AgNPs. The enhancement of the PEC response was attributed to the effect of the surface plasmon local fields of the AgNPs, which induce efficient generation and quick separation of the electron-hole pairs in FLG.