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, In2O3 nanoparticle/Bi4O5Br2 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 Bi4O5Br2 (50.2%) and In2O3 (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 In2O3 nanoparticles/ Bi4O5Br2 nanosheets could enhance the adsorption of O-2 and promote the generation of superoxide radicals (center dot 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.

Automated summary

The construction of In2O3 nanoparticle/Bi4O5Br2 nanosheet S-scheme heterojunction with interface oxygen vacancies (OVs) was achieved in this study using a hydrothermal-calcination approach and a simple chemical precipitation process. The composite exhibited enhanced photocatalytic degradation efficiency for tetracycline hydrochloride (TCH) under simulated sunlight, with a degradation rate of 92.4%, significantly higher than that of pure Bi4O5Br2 (50.2%) and In2O3 (28.6%). The synergistic effect of S-scheme heterojunctions and interface OVs accelerated the complexation of unwanted electrons and holes, contributing to the high removal efficiency. Furthermore, the presence of abundant OVs in the composite promoted the adsorption of O-2 and the generation of superoxide radicals.