Au nanoparticles sensitized ZnO nanorod@nanoplatelet core–shell arrays for enhanced photoelectrochemical water splitting

Abstract

Au nanoparticles sensitized ZnO nanorod@nanoplatelet (NR@NP) core–shell arrays have been synthesized via a facile hydrothermal method followed by a further modification using Au nanoparticles. The resulting Au–ZnO NR@NP nanoarray exhibits promising behavior in photoelectrochemical (PEC) water splitting, giving rise to a largely enhanced photocurrent density, photoconversion efficiency as well as incident-photon-to-current-conversion efficiency (IPCE), much superior to those of pristine ZnO nanorods arrays and ZnO NR@NP. This is attributed to the coordination of ZnO core–shell hierarchical nanostructure and the surface-plasmon-resonance effect of Au nanoparticles, which facilitates the exposure of active sites and utilization of visible light. Density functional theory (DFT) calculations further confirm that the photogenerated electrons of ZnO transfer to Au, which suppresses the recombination of electron–hole pairs. Therefore, this work provides a facile and cost-effective strategy for the construction of hierarchical metal/semiconductor nanoarrays, which can be potentially used in the field of energy storage and conversion.