Three-dimensional ZnO@TiO2 core-shell nanostructures decorated with plasmonic Au nanoparticles for promoting photoelectrochemical water splitting

Abstract A novel three-dimensional (3D) core-shell nanostructure decorated with plasmonic Au nanoparticles (NPs) was prepared for photoelectrochemical water splitting. In the new nanostructure, ZnO nanorods (NRs) are perpendicular to ZnO nanosheets (NSs), and the ZnO NSs-NRs are coated with a thin TiO2 shell formed by liquid phase deposition. The plasmonic Au NPs were formed in situ on the surface of ZnO NSs-NRs@TiO2 by thermal reduction. A thin TiO2 shell and uniformly distributed Au NPs were successfully obtained. The photoconversion efficiency and photocurrent density of the 3D ZnO NSs-NRs@TiO2-Au nanostructure respectively reached 0.48% and 1.73 mA cm−2 at 1.23 V vs. reversible hydrogen electrode, 4.80 and 4.33 times higher than those of ZnO NSs, respectively. The thin TiO2 shell effectively promoted charge separation, while the surface plasmon resonance effects of the Au NPs improved the photocurrent density. The findings suggest that the 3D ZnO NSs-NRs@TiO2-Au nanostructure is a promising photoanode for photoelectrochemical water splitting.