Interfacial Bi-S chemical bond-coupled sulfur vacancy in Bi4NbO8Cl@ZnIn2S4_x S-scheme heterojunction for superior photocatalytic hydrogen generation

Strategies such as reducing charge transfer resistance and enhancing transmission driving force are considered effective in achieving higher photocatalytic performance. In this study, Bi4NbO8Cl@ZnIn2S4_x S-scheme heterojunction photocatalyst with atomic-level interface Bi-S chemical bond connection was successfully constructed through in-situ growth of ZnIn2S4_x nanosheets containing sulfur vacancies (Sv) on Bi4NbO8Cl microplates. Firstly, the S-scheme charge transfer mode effectively spatially separated photogenerated carriers while retaining their reactivity to the maximum extent. Secondly, the interfacial Bi-S bond served as a "bridge" to lessen the interface resistance and provide a high-speed channel for the transmission of photogenerated carriers. Lastly, Sv effectively expanded the Fermi level (Ef) difference between the two semiconductors in the heterojunction, so as to enlarge the built-in electric field (IEF) at the interface and reinforce the driving force for charge transfer. Owing to the synergistic effects of these advantages, the Bi4NbO8Cl@ZnIn2S4_x composite exhibited an average hydrogen production rate of up to 8.7 mmol g _ 1 h _ 1 under visible light, which was 4.0 and 14.5 times that of ZnIn2S4_x and Bi4NbO8Cl samples, respectively. This work presents a novel approach for designing interfacial chemically bonded S-scheme heterojunction photocatalysts with high catalytic activity.