ZnWO4-ZnIn2S4 S-scheme heterojunction for enhanced photocatalytic H2 evolution

The recombination of photogenerated electrons and holes is a crucial factor limiting photocatalytic H-2 evolution. The S-scheme ZnWO4-ZnIn2S4 heterojunction with 2D coupling interfaces was successfully synthesized using a simple solvothermal method. An effective S-scheme interfacial charge migration route at the S-scheme heterogeneous interface was determined by energy band structure analyses (such as UPS, Mott-Schottky and XPS plots), which facilitates the separation of photoexcited carriers. It is worth noting that the optimal ZnWO4-ZnIn2S4 composite has an H-2 evolution activity of 4925.3 mu mol g(-1) h(-1) with favourable photostability and stability. Meanwhile, the ZnWO4-ZnIn2S4 heterojunction exhibits the maximum optical response value (2.8 mA cm(-2)) in the initial stage, effectively promoting the separation and migration of photogenerated carriers. The establishment of the built-in electric field direction at the interface can effectively promote the space charge separation between the ZnWO(4 )and ZnIn2S4 nanosheets, which is favorable to the photocatalytic H-2 evolution. This work provides valuable guidance for designing S-scheme heterojunction photocatalysts composed of two n-type semiconductors for energy and environmental applications. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

A successful synthesis of a 2D coupling interface S-scheme ZnWO4-ZnIn2S4 heterojunction was achieved, and an effective interfacial charge migration pathway was determined, facilitating the separation of photoexcited carriers. The optimized ZnWO4-ZnIn2S4 composite exhibited high H-2 evolution activity and photostability. The heterojunction also showed maximum optical response in the initial stage, promoting the separation and migration of photogenerated carriers. This study provides valuable guidance for the design of S-scheme heterojunction photocatalysts.