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

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 0.9 Zn 0.1 S/ZnWO 4 (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. A tetrapod-shaped Cd 0.9 Zn 0.1 S/ZnWO 4 S-scheme heterojunction with advanced hydrogen evolution performance was developed. The lattice relaxation and electron localization at the interface were investigated. An S-Zn charge exchange channel in the structural level behind the S-scheme heterojunction mechanism was clarified. • Developed a Cd₀.₉Zn₀.₁S/ZnWO₄ S-scheme heterojunction photocatalyst with a novel S-Zn charge channel. • Interfacial lattice relaxation and electron localization significantly enhanced charge separation and transfer. • Achieved 3.69-fold and 4.63-fold higher hydrogen evolution rates than Cd₀.₉Zn₀.₁S and ZnWO₄, respectively. • Combined experimental and DFT analysis provided deep insights into charge transfer dynamics in S-scheme heterojunctions.