Construction of dual Z-scheme g-C3N4/BiVO4 (0 4 0)/In2S3 photocatalyst for efficient photocatalytic degradation and sterilization under solar light irradiation

A novel ternary heterojunction photocatalyst, g-C3N4/BiVO4/In2S3, is synthesized via a hydrothermal method, exhibiting superior photocatalytic activity in tetracycline (TC) degradation and Escherichia coli (E. coli) inactivation. The first-order kinetic constant of TC degradation by MCN/BVO/InS-1 under simulated solar light is 3.6, 1.8, 2.9 and 1.4 times that of MCN, BVO, InS, and MCN/BVO, respectively. More than 90 % of E. coli can be inactivated within 60 min by MCN/BVO/InS composite. After three consecutive cycles of experiments, the prepared photocatalyst showed continuous excellent stability. In this system, superoxide radicals (∙O2-) dominate TC degradation, while photogenerated h+ is key in E. coli inactivation. TC degradation pathways are analyzed by LC-MS/MS and theoretical calculations. A dual Z-scheme electron transfer mechanism is proposed. Furthermore, the ecotoxicity of TC and its degradation intermediates is examined through the application of the Toxicity Estimation Software Tool (T.E.S.T.) and Quantitative Structure-Activity Relationship (QSAR) model. The findings of the MCN/BVO/InS photocatalyst could provide insights for designing and optimizing novel photocatalytic systems with broader applications in the remediation of waterborne contaminants.