WO3@Fe2O3Core-ShellHeterojunctionPhotoanodesforEfficientPhotoelectrochemicalWaterSplitting

Photoelectrochemical（PEC） hydrogen production from water splitting is a green technology to convert solar energy into renewable hydrogen fuel. The construction of host/guest architecture in semiconductor photoanodes has been proven to be an effective strategy to improve solar-to-fuel conversion efficiency. In this study, WO3@Fe2O3 core-shell nanoarray heterojunction photoanodes are synthesized from the in-situ decomposition of WO3@Prussian blue（WO3@PB） and then used as host/guest photoanodes for photoelectrochemical water splitting, during which Fe2O3 serves as guest material to absorb visible solar light and WO3 can act as host scaffolds to collect electrons at the contact. The prepared WO3@Fe2O3 shows the enhanced photocurrent density of 1.26 m A cm-2（under visible light） at 1.23 V. vs RHE and a superior IPEC of 24.4% at 350 nm, which is higher than that of WO3@PB and pure WO3(0.43 m A/cm-2 and 16.3%, 0.18 m A/cm-2 and 11.5%) respectively, owing to the efficient light-harvesting from Fe2O3 and the enhanced electron-hole pairs separation from the formation of type-Ⅱ heterojunctions, and the direct and ordered charge transport channels from the one-dimensional（1D） WO3 nanoarray nanostructures. Therefore, this work provides an alternative insight into the construction of sustainable and cost-effective photoanodes to enhance the efficiency of the solar-driven water splitting.