TiO2/In2S3 S-scheme photocatalyst with enhanced H2O2-production activity

Photocatalytic production of hydrogen peroxide (H2O2) is an ideal pathway for obtaining solar fuels. Herein, an S-scheme heterojunction is constructed in hybrid TiO2/In2S3 photocatalyst, which greatly promotes the separation of photogenerated carriers to foster efficient H2O2 evolution. These composite photocatalysts show a high H2O2 yield of 376 µmol/(L·h). The mechanism of charge transfer and separation within the S-scheme heterojunction is well studied by computational methods and experiments. Density functional theory and in-situ irradiated X-ray photoelectron spectroscopy results reveal distinct features of the S-scheme heterojunction in the TiO2/In2S3 hybrids and demonstrate charge transfer mechanisms. The density functional theory calculation and electron paramagnetic resonance results suggest that O2 reduction to H2O2 follows stepwise one-electron processes. In2S3 shows a much stronger interaction with O2 than TiO2 as well as a higher reduction ability, serving as the active sites for H2O2 generation. The work provides a novel design of S-scheme photocatalyst with high H2O2 evolution efficiency and mechanistically demonstrates the improved separation of charge carriers.