Interfacial lattice relaxation and S-Zn charge channel engineering in Cd₀.₉Zn₀.₁S/ZnWO₄ S-scheme heterojunction photocatalysts

Abstract

In the S-scheme heterojunction, photogenerated electrons from the oxidation photocatalyst recombine with holes from the reduction photocatalyst, enhancing redox potential and boosting photocatalytic activity. However, the recombination mechanism at these interfaces remains largely unexplored. In this study, we design a Cd_0.9Zn_0.1S/ZnWO₄ (CZS/ZWO) S-scheme heterojunction model guided by theoretical predictions. Remarkably, a nano-tetrapod-shaped CZS/ZWO S-scheme heterojunction is synthesized via a simple solvothermal and ultrasonic self-assembly method, achieving hydrogen evolution performance under visible light irradiation for 3 h that is 3.69 times higher than CZS alone and 4.63 times higher than ZWO alone. Further theoretical calculations simulate the charge transfer mechanism, electron density localization, and transition states in the photocatalytic hydrogen evolution reaction. Finally, integrating theoretical and experimental data, an S-Zn channel is proposed within the CZS/ZWO S-scheme heterojunction, clarifying the electron transfer pathway. This study provides a detailed understanding of charge transfer dynamics in S-scheme heterojunction.