Mechanism Decoding of an S-Scheme ZnIn<sub>2</sub>S<sub>4</sub>/H<sub>2</sub>WO<sub>4</sub> Heterojunction with Favorable Surface Electronic Potential for Enhanced and Anti-Corrosion Photocatalytic Hydrogen Evolution
Honghai Miao, Jiangbo Wu, Xi Luo, Xin Li, Zhao Mo, Jinyuan Liu, Zaiyong Jiang, Jianjian Yi, Xianglin Zhu, Hui Xu
Abstract
The rational construction of heterojunction interfaces plays a critical role in enhancing the carrier separation efficiency for photocatalytic hydrogen evolution. In this study, a ZnIn 2 S 4 /H 2 WO 4 S-scheme heterojunction was successfully synthesized via a self-assembly strategy. Compared with conventional WO 3, the H 2 WO 4 component exhibits a lower work function, which significantly promotes surface electron overflow and establishes an optimized S-scheme charge transfer pathway. Structural characterization reveals that the intimate integration of H 2 WO 4 nanosheets within ZnIn 2 S 4 nanoflowers provides enhanced interfacial contact, thereby facilitating efficient charge separation and migration. As a result, the optimized ZnIn 2 S 4 /H 2 WO 4 composite demonstrates a hydrogen evolution rate of 138 mmol/g/h, achieving a 4.7-fold enhancement over pristine ZnIn 2 S 4 and a 1.9-fold improvement compared to the ZnIn 2 S 4 /WO 3 . This work highlights the dual requirements for oxidation photocatalysts in S-scheme systems: precise band gap alignment and favorable surface electronic properties, both essential for enabling efficient electron overflow and ensuring effective S-scheme charge migration channels.