One-Step Coating of a ZnS Nanoparticle/MoS₂Nanosheet Composite on Supported ZnO Nanorods as Anodes for Photoelectrochemical Water Splitting

ZnO-based photoanodes absorb a limited spectrum of light, and their photogenerated electrons and holes combine easily. Such features limit their photoelectrochemical activity. Herein, we report the synthesis of ternary heterostructures comprising ZnO nanorods (NRs) and ZnS nanoparticles wrapped in MoS2 nanosheets (ZnO/ZnS/MoS2, ZSM) directly grown on a substrate by a low-cost hydrothermal route and their performance as anodes for photoelectrochemical water splitting. The ZSM heterostructures exhibit a sixfold photocurrent density of 0.72 mA cm-2, a fourfold maximum applied bias photon-to-current efficiency of 0.28% compared to bare ZnO NRs, and excellent photostability. These improvements in the overall photoelectrochemical activity are due to enhanced light absorption in the visible light range, higher surface active sites, and efficient charge separation enabled by the introduction of a ZnS/MOS2 coating. Our study demonstrates an alternative architecture design of ternary heterostructures with increased photoelectrochemical activity. In general, this approach of constructing a double heterojunction can also be extended to other materials with similar architectures.