Construction of zinc-oxygen double vacancies BiOCl/ZnS Z-scheme heterojunction and photocatalytic degradation of norfloxacin

Defect (vacancy) engineering can modulate the catalyst surface atoms and electrons, which is a low-cost and effective modification strategy for Z-scheme heterojunction. In this paper, metal and non-metal double vacancies (VZn+O) Z-scheme heterojunction photocatalysts (BiOCl/ZnS−VZn+O) were synthesized for the degradation of norfloxacin (NOR) for the first time. The results show that the built-in electric field of BiOCl/ZnS−VZn+O catalyst induces the directional migration of photogenerated carriers, which greatly improves the carrier migration and separation efficiency. The introduced nonmetallic (O) vacancies can lower the conduction band of BiOCl, while the metallic (Zn) vacancies can enhance the valence band of ZnS. Due to the synergistic efficiency formed by the double vacancies and Z-scheme heterojunction, BiOCl/ZnS−VZn+O showed excellent performance in photodegradation of NOR (97.9% degradation rate of 20 mg/L NOR in 50 min photodegradation). In addition, the mechanism of action, intermediates and degradation pathways of photodegradation were discussed in detail.