Construction of ZnIn₂S₄/Cu2O Z-scheme heterojunction for enhanced photocatalytic tetracycline degradation

In this study, a novel Z-type heterojunction photocatalyst ZnIn₂S₄/Cu 2 O was successfully constructed for the efficient degradation of tetracycline in aquatic environments. Flower-like ZnIn₂S₄ microspheres and cubic Cu 2 O were prepared via hydrothermal and water bath synthesis methods, respectively, and then composited through a solid-state pyrolysis-assisted ultrasonic dispersion method to form ZIC composites with different mass ratios (ZIC-2, ZIC-4, ZIC-6). Characterization results show that Cu 2 O nanoparticles are uniformly loaded onto the surface of ZnIn₂S₄ microspheres, forming a close heterojunction interface. Under visible light irradiation, ZIC-4 achieved a TC degradation efficiency of 91.2% within 60 min, significantly outperforming pristine ZnIn₂S₄ and Cu 2 O. Photoelectrochemical tests indicate that the Z-type heterojunction effectively promotes the separation and migration of photogenerated electron-hole pairs and suppresses charge carrier recombination. Radical trapping experiments and EPR tests confirm that superoxide radicals (·O₂ − ) and holes (h + ) are the main reactive species. The composite also exhibits good photostability and recyclability, providing a novel and efficient photocatalytic material for visible-light-driven removal of antibiotic pollutants from water.