Electron Tandem Transport Channel in a Cu3P/Sv-ZnIn2S4 p–n Heterojunction for Photothermal-Photocatalytic Benzyl Alcohol Oxidation and H2 Production

The development of photocatalytic systems with an electron tandem transport channel represents a promising avenue for improving the utilization of photogenerated electrons and holes despite encountering significant challenges. In this study, ZnIn₂S₄ (Sv-ZIS) with sulfur vacancies was fabricated using a solvothermal technique to create defect energy levels. Subsequently, Cu₃P nanoparticles were coupled onto the surface of Sv-ZIS, forming a Cu₃P/Sv-ZIS p-n heterojunction with an electron tandem transport channel. Experimental findings demonstrated that this tandem transport channel enhanced the carrier lifetime and separation efficiency. In addition, mechanistic investigations unveiled the formation of a robust built-in electric field (BEF) at the interface between Cu₃P and Sv-ZIS, providing a driving force for electron migration. The combined consequences of the transport channel, the strong BEF, and photothermal effect led to a surface carrier separation efficiency of 65.85%. Consequently, Cu₃P/Sv-ZIS achieved simultaneous H₂ yield and benzaldehyde production rates of 18,101.4 and 15,012.6 μmol·g^-1·h^-1, which were 2.31 and 2.62 times higher than those of ZnIn₂S₄, respectively. This work exemplifies the design of the p-n heterojunction for the efficient utilization of photogenerated electrons and holes.