Hierarchical MoO2/ZnIn2S4 Schottky Heterojunction Stimulated Photocatalytic H2 Evolution under Visible Light

A Schottky junction is an ideal candidate for photocatalytic H2 evolution since the photo-induced charge kinetics of semiconductors can be harnessed via coupling with metals. In this work, the ZnIn2S4 semiconductor and metallic MoO2 are successfully integrated to form a composite photocatalyst, which is analogous to the conventional metal–semiconductor Schottky junction. In such a heterojunction, hierarchical ZnIn2S4 flower-like structures are in situ grown on MoO2 nanosheets. The experimental and computational results suggest that the Schottky barrier successfully suppresses the recombination of photocarriers, while MoO2 further extends the spectral range of light absorption and decreases the activation energy of H2 evolution. As a result, the optimal MoO2/ZnIn2S4 composite exhibits a 28.2 times higher H2 evolution rate (3730.5 μmol/g/h) than pristine ZnIn2S4 under visible light.