Synthesis of S‐scheme CoIn₂S₄/SnO2‐x Composite Materials Constructed by Heterojunction and Defect Engineering for Highly Efficient Photocatalytic Degradation of Organic Pollutants

Rapid degradation of organic pollutants in raw sewage is crucial from an environmental protection perspective. Semiconductor photocatalysts with S‐scheme heterojunction are considered highly effective for sewage treatment. Defect engineering was applied to SnO 2 materials to reduce their band gap. The CoIn 2 S 4 /SnO 2‐x composite catalyst with S‐scheme heterojunction was synthesized via a hydrothermal method followed by oil‐bath approach. SEM image showed that the morphology of the CoS x ‐1 composite photocatalyst is of a sea urchin‐like structure with CoIn 2 S 4 wrapped around the spherical surface of SnO 2‐x material. Different characterization techniques including XPS, Photoelectrochemical measurements, et al. and free radical trapping experiments demonstrated the existence of S‐scheme heterojunction at the CoIn 2 S 4 and SnO 2‐x interface. Photocatalytic degradation of the RhB demonstrate that the CoS x ‐1 composite photocatalyst exhibits significantly enhanced catalytic performance （97.8% degradation), compared to the individual CoIn 2 S 4 and SnO 2‐x . The improved photocatalytic performance is attributed to the establishment of the S‐scheme heterojunction. Additionally, the CoS x ‐1 composite photocatalyst exhibited high stability before and after the catalytic reaction. This work provides an insight into developing new composite photocatalysts with s‐scheme heterojunctions for addessing water pollution.