Synergistic Coupling of Interfacial Oxidation Sites and S-Scheme Heterojunction in Cu₂WS₄@SnIn₄S₈ Core–Shell Nanocomposites Boosting CO₂ Photoreduction Efficiency

Photocatalytic CO₂ reduction offers a dual solution to mitigate the energy crisis and reduce carbon emissions. In situ synthesis of the Cu₂WS₄@SnIn₄S₈ (CWS@SIS) composite has established S-S bonds at the interface, which act as atomic-scale interfacial "bridges" to stabilize the heterojunction interface. SnIn₄S₈ nanosheets are uniformly dispersed on the Cu₂WS₄ surface, activating the (101) crystal plane of Cu₂WS₄ to consume photogenerated holes. In addition, the S-scheme heterojunction facilitates efficient charge carrier separation and transfer. Under the synergistic effects of (101) plane activation and the S-scheme heterojunction, the CWS@SIS core-shell composite achieves photocatalytic CO₂ reduction rates of 10.98 μmol·g^-1·h^-1 for CH₄ and 3.85 μmol·g^-1·h^-1 for CO. This work proposes a novel strategy for advancing the design and application of core-shell S-scheme heterojunction photocatalysts.