In situ irradiated XPS investigation on S-scheme ZnIn2S4@COF-5 photocatalyst for enhanced photocatalytic degradation of RhB

Recently, the step-scheme (S-scheme) heterojunction has gained significant attention due to its effective electron-hole separation and strong redox capabilities. However, reports on covalent organic framework (COF)-based S-scheme heterojunctions for photocatalytic RhB degradation remain limited. In this study, an S-scheme ZnIn2S4@COF-5 heterojunction photocatalyst was successfully synthesized by growing COF-5 on the surface of ZnIn2S4 nanosheets, achieving efficient RhB degradation. Using 30 mg of ZnIn2S4@COF-5, we degraded 50 mL of an 80x10(-6) RhB solution, achieving a 97% removal rate within 90 min. The photocatalytic performance of the ZnIn2S4@COF-5 S-scheme heterojunction was approximately 1.7 times higher than that of ZnIn2S4 and 1.6 times higher than COF-5 alone. Compared to the other reported COF-based S-scheme heterojunctions and commercial photocatalysts, this ZnIn2S4@COF-5 photocatalyst exhibited superior photocatalytic performance. The S-scheme charge transfer mechanism of the ZnIn2S4@COF-5 heterojunction was elucidated through in situ irradiated XPS. Experimental results demonstrate that this rational design not only facilitates the effective separation of photogenerated electrons and holes, but also provides a large surface area and abundant active sites for efficient RhB degradation. (c) 2024 The Authors. Published by Elsevier B.V. on behalf of The Chinese Ceramic Society. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).