Efficient photocatalytic tetracycline elimination over Z-scheme g-C3N4/Bi5O7I heterojunction under sunshine light: Performance, mechanism, DFT calculation and pathway

A series of Z-scheme heterojunction g-C₃N₄/Bi₅O₇I composites were fabricated via a facile electrostatic self-assembly procedure. The optimum 15%-g-C₃N₄/Bi₅O₇I displayed good degradation efficiency toward tetracycline (TC) under visible light irradiation. The improvement of photocatalytic efficiency was mainly attributed to the generation of photo-induced h⁺ and O₂^•− radical. The migration route of photo-induced h⁺ and e⁻ between g-C₃N₄ and Bi₅O₇I was investigated by XPS analysis, EPR test, photocatalytic mechanism and DFT calculations. The degradation pathways and the toxicological simulation of TC were evaluated. It was revealed that the intermediates produced during degradation process exhibited lower toxicity than the pristine TC. In addition, 15%-g-C₃N₄/Bi₅O₇I exhibited good stability and reusability. Considering its potentials in practical application, 15%-g-C₃N₄/Bi₅O₇I displayed high photocatalytic efficiency under natural sunlight irradiation. In all, this work offered a deep insight into the photocatalytic mechanism of tetracycline degradation over bismuth-rich bismuth oxyhalide/g-C₃N₄ heterojunction photocatalysts.