Plasmon-enhanced strong visible light photocatalysis by defect engineered CVD graphene and graphene oxide physically functionalized with Au nanoparticles

The strong visible light photocatalytic activity of defect-controlled CVD graphene (GR) and graphene oxide (GO) hybrids through physical functionalization with Au atoms has been demonstrated here. Control of inplane defects in GR was achieved by controlling the pre-treatment of substrates during the CVD reaction, and post-growth functionalization was achieved using a physical sputter deposition approach. Quantitative analysis of the defect density, oxygenated functional groups on GR and nature of the interaction of Au with GR and GO was performed using several analytical tools. The defect-mediated strong interaction of the Au NPs with GR and GO and enhanced visible absorption was evidenced from surface plasmon resonance and surface-enhanced Raman spectroscopy studies. As compared to the pristine GR with a photocatalytic efficiency of similar to 30%, Au-functionalized defective GR and GO films exhibited catalytic efficiencies of 70% and 85%, respectively, for the first time. The pseudo first-order rate constant of degradation with visible light was found to be similar to 10(-3) min(-1). This is believed to result from the superior charge transfer in graphenebased plasmonic hybrids aided by enhanced light absorption. Our results open up doors for the efficient visible light photocatalysis and photoelectrocatalysis applications of graphene-based 2D layered materials.