One-pot synthesis of S-scheme WO3/BiOBr heterojunction nanoflowers enriched with oxygen vacancies for enhanced tetracycline photodegradation

Construction of S-scheme heterojunctions that efficiently separate photogenerated electrons and holes is an emerging strategy for the development of high-efficiency performance photocatalysts for the photodegradation of organic pollutants. In this study, S-scheme WO3/BiOBr heterojunction nanoflowers enriched with oxygen vacancies (Vo) were synthesized for the first time via a one-pot hydrothermal method without the addition of surfactants. The XPS characterization of the WO3/BiOBr-Vo indicated the formation of internal electric field at the WO3/BiOBr interface, which facilitated charge separation and charge transfer. The superior ability of WO3/BiOBr-Vo to separate photoinduced electron-hole pairs was confirmed by photoluminescence and photocurrent responses. As a result, the optimal 25WO(3)/BiOBr-Vo photocatalyst decomposed 100% tetracycline after 50 min of visible light irradiation while pure BiOBr-Vo and WO3 decomposed less than 90% and 40% of tetracycline, respectively. The EPR analysis and free radicals trapping experiments found that the center dot O-2(-) was the main active species in the photocatalytic mechanism. The oxygen vacancies provided readily accessible reaction sites for the conversion of O-2 to center dot O-2(-). Toxicity assessment revealed that the aquatic toxicity of tetracycline was efficiently reduced after photodegradation. This study demonstrated a promising method for the development of highperformance photocatalysts based on band structure optimization and crystal defect engineering.

Automated summary

The construction of S-scheme heterojunctions with efficient charge separation is a promising strategy for the development of high-performance photocatalysts. This study successfully synthesized oxygen vacancy-enriched WO3/BiOBr heterojunction nanoflowers and demonstrated their superior photocatalytic performance for the degradation of organic pollutants. The oxygen vacancies in the heterojunction provide accessible reaction sites and facilitate charge separation and transfer, resulting in enhanced photocatalytic activity and reduced aquatic toxicity of the pollutants.