Fabricated ZnIn2S4/Cu2S S-scheme heterojunction with snowflake structure for boosting photocatalytic CO2 reduction in gas–solid reactor

Designing S-scheme heterojunctions has become a powerful strategy to enhance photocatalytic activity and improve the localization of catalyst surface charge. Therefore, more and more research has been devoted to S-scheme heterojunctions. In this work, we employed a simple two-step hydrothermal method to fabricate S-scheme ZnIn2S4/Cu2S (ZIS/Cu2S) heterojunctions. The results show that the composites exhibit good performance in the photoreduction of CO2 to CO and CH4. Especially, at 40 %-ZIS/Cu2S, the release rates of CO and CH4 were 13.35 μmol g−1 and 34.81 μmol g−1 under the condition of a 4 h reaction, and the selectivity of CH4 reached 80 %. In addition, the in situ FTIR test revealed that the catalyst promoted the formation of the key intermediates COOH* and CH3O* under the effect of light interaction, which was favorable to the photoreduction of CO2. This indicates that the electron transfer path of S-type not only promotes the separation of carriers for conversion but also has a strong redox ability to selectively convert CO2 to CH4, which provides some thoughts for the design of S-scheme heterojunction photocatalysts. This provides some thoughts for the design of S-scheme heterojunction photocatalysts. © 2024 Elsevier Ltd