Large-Scale Synthesis of Porous Bi₂O₃ with Oxygen Vacancies for Efficient Photodegradation of Methylene Blue

Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics. Bismuth oxide (Bi _2 O _3 ) nanocrystals with a bandgap ranging from 2.0 eV to 2.8 eV have attracted increasing attention due to high activity of photodegradation of organic pollutants by utilizing visible light. Though several methods have been developed to prepare Bi _2 O _3 -based semiconductor materials over recent years, it is still difficult to prepare highly active Bi _2 O _3 catalysts in large scale with a simple method. Therefore, developing simple and feasible methods for the preparation of Bi _2 O _3 nanocrystals in large scale is important for the potential applications in industrial wastewater treatment. In this work, we successfully prepared porous Bi _2 O _3 in large scale via etching commercial BiSn powders, followed by thermal treatment with air. The acquired porous Bi _2 O _3 exhibited excellent activity and stability in photocatalytic degradation of methylene blue. Further investigation of the mechanism witnessed that the suitable band structure of porous Bi _2 O _3 allowed the generation of reactive oxygen species, such as O _2 ^-\cdot and \cdot OH, which effectively degraded MB.