Hot electron assisted photoelectrochemical water splitting from Au-decorated ZnO@TiO₂ nanorods array

Engineering of semiconductor nanomaterials is critical to enhance the photoelectrochemical (PEC) performance for water splitting. However, semiconductors often show the low light absorption, slow charge transfer, and easy recombination of carriers, thus leading to the low catalytic efficiency. In this work, we show facile synthesis of ZnO@TiO₂ core–shell nanorods (NRs) arrays modified with Au nanoparticles (NPs) as the photoelectrode for PEC water splitting. Impressively, the obtained ZnO@TiO₂(15 nm)/Au(8 nm) array shows the maximum photocurrent density of 3.14 mA/cm² at 1.2 V vs. reversible hydrogen electrode (RHE), 2.6 times and 1.7 times higher than those obtained from ZnO NRs and ZnO@TiO₂(15 nm) arrays. The electric-field simulation and transient absorption spectroscopy show that the Au-decorated core–shell nanostructures have an enhanced hot electron generation and prolonged decay time, indicating effective charge transfer and recombination inhibition of carriers. This work provides an efficient preparation strategy for photoelectrodes as well as great potential for the large-scale development of this technology.