In₂O₃ Nanoparticle/Bi₄O₅Br₂ Nanosheet S-Scheme Heterojunctions with Interfacial Oxygen Vacancies for Photocatalytic Degradation of Tetracycline

The development of highly efficient photocatalysts for antibiotics contamination in water remains a severe challenge. In this study, In 2 O 3 nanoparticle/Bi 4 O 5 Br 2 nanosheet S-scheme heterojunction with interface oxygen vacancies (OVs) was constructed by a hydrothermal-calcination approach and a simple chemical precipitation process. Under simulated sunlight, this composite showed enhanced degradation efficiency for tetracycline hydrochloride (TCH) with 92.4%, which was much higher than those of pure Bi 4 O 5 Br 2 (50.2%) and In 2 O 3 (28.6%). The excellent removal efficiency was mainly attributed to the synergistic effect of S-scheme heterojunctions and interface OVs accelerating the complexation of unwanted electrons (e – ) and holes (h + ), thus retaining e – with the strong oxidizing ability and h + with the strong reducing ability to participate in the reaction. In addition, the abundant OVs in In 2 O 3 nanoparticles/Bi 4 O 5 Br 2 nanosheets could enhance the adsorption of O 2 and promote the generation of superoxide radicals (·O 2 – ). The toxicity of the tetracycline degradation products and the catalyst was evaluated by E. coli growth inhibition experiments. Based on the TCH intermediates detected by HPLC-MS, three possible TCH degradation pathways were proposed. This study shows that the construction of S-scheme heterojunctions with interfacial defects is an effective strategy for the preparation of efficient photocatalysts.