Surface-Plasmon-Enhanced Band Emission and Enhanced Photocatalytic Activity of Au Nanoparticles-Decorated ZnO Nanorods

We reported a simple hydrothermal method to fabricate Au nanoparticles-decorated ZnO nanorods (ZnO-NRs) using aligned ZnO-NRs arrays as a template. Via changing the concentration of HAuCl4 aqueous solution, the size and density of Au nanoparticles (NPs) on the surface of ZnO-NRs could be readily tuned. The photoluminescence of Au-NPs decorated ZnO-NRs were investigated, in order to optimize the configuration of the Au-NPs decorated ZnO-NRs system realizing the maximum band emission. Due to a synergistic effect of the adjacent Au NPs and ZnO-NRs and efficiently coupled localized surface plasmon resonance (SPR) excitation, an optimized sample employing Au NPs with 15-nm size showed best catalytic efficiency. We have proposed a mechanism that is the electron transfer from surface-plasmon-stimulated \Au NPs to the conduction band of ZnO-NRs. These results demonstrate that Au NPs can significantly enhance the charge separation by extracting electrons from the photoexcited ZnO and consequently improve the photocatalytic activity of the composites.