TiO2/FePS3 S-Scheme Heterojunction for Greatly Raised Photocatalytic Hydrogen Evolution

The aggravating extreme climate changes and natural disasters stimulate the exploration of low-carbon/zero-carbon alternatives to traditional carbon-based fossil fuels. Solar-to-hydrogen (STH) transformation is considered as appealing route to convert renewable solar energy into carbon-free hydrogen. Restricted by the low efficiency and high cost of noble metal cocatalysts, high-performance and cost-effective photocatalysts are required to realize the realistic STH transformation. Herein, the 2D FePS3 (FPS) nanosheets anchored with TiO2 nanoparticles (TiO2/FePS3) are synthesized and tested for the photocatalytic hydrogen evolution reaction. With the integration of FPS, the photocatalytic H-2-evolution rate on TiO2/FePS3 is radically increased by approximate to 1686%, much faster than that of TiO2 alone. The origin of the greatly raised activity is revealed by theoretical calculations and various advanced characterizations, such as transient-state photoluminescence spectroscopy/surface photovoltage spectroscopy, in situ atomic force microscopy combined with Kelvin probe force microscopy (AFM-KPFM), in situ X-ray photoelectron spectroscopy (XPS), and synchrotron-based X-ray absorption near edge structure. Especially, the in situ AFM-KPFM and in situ XPS together confirm the electron transport pathway in TiO2/FePS3 with light illumination, unveiling the efficient separation/transfer of charge carrier in TiO2/FePS3 step-scheme heterojunction. This work sheds light on designing and fabricating novel 2D material-based S-scheme heterojunctions in photocatalysis.