Construct a Heterojunction Interface to Induce and Complete Hole-Dominated Cascade Reaction

Carrier separation efficiency influences the final reactive oxygen species product of the cascade reaction, and constructing a heterojunction interface is an ideal strategy to improve it. Herein, a self-sufficient photo-Fenton system is engineered using a Cu_xO/CuS/ZnIn₂S₄ heterojunction, which enables the directional generation of sufficient singlet oxygen (¹O₂) via a hole-dominated cascade reaction, achieving efficient degradation of amoxicillin. The CuS interface between Cu_xO and ZnIn₂S₄ originates from the in situ transformation of Cu_xO, and the stepwise presence of different components during the XRD, XPS, and TEM structure characterization confirms it. This heterojunction interface induces a band structure from initial type I to S-scheme, optimizing carrier separation efficiency and transfer pathway, which matches with hole-dominated cascade reactions. Consequently, H₂O₂ is in situ produced via water oxidation reaction and eventually converted into ¹O₂ by highly active holes. In addition, the CuS interface prevents amoxicillin in the aqueous system from directly reacting with holes while ensuring that H₂O molecules adequately participate in the cascade reaction. In summary, the tailored heterojunction interface boosts carrier separation efficiency, driving the completion of the hole-dominated cascade reaction. This process facilitates the directional generation of abundant ¹O₂ for the efficient degradation of contaminants.