Sunlight driven isotropic β-Bi₂O₃ with high charge-carrier mobility for the efficient degradation of bisphenol A and...

Nanostructured β-Bi₂O₃ was synthesized and used for the photocatalytic degradation of bisphenol A and phenol. After 90 minutes of sunlight irradiation, the degradation efficiencies toward bisphenol A and phenol were 96% and 97%, respectively. Changes in sunlight due to the season and the calcination temperature and duration displayed weak influence on the degradation efficiencies for these two pollutants. Although the use of tap water, river water, lake water, and seawater exhibited a certain impact on the photocatalytic efficiency, the final removal efficiencies for bisphenol A and phenol in seawater still reached 89% and 90%, respectively. Moreover, the photocatalytic efficiencies toward bisphenol A and phenol remained above 91% and 86% during testing over five cycles. Superoxide groups (O₂^-) and holes were the main active substances, while hydroxyl radicals (˙OH^-) also played a certain role in photocatalysis. The charge-carrier concentration and mobility of β-Bi₂O₃ were 4.82 × 10²¹ cm^-3 and 4.0017 cm² V^-1 s^-1, respectively, based on the Hall test. β-Bi₂O₃ was an isotropic semiconductor based on first-principles calculations, and its excellent photocatalytic activity originated from the high electron mobility and moderate hole mobility. The bisphenol A and phenol degradation mechanisms on the β-Bi₂O₃ surface were revealed based on adsorption model calculations. Finally, the reduction in total organic carbon content further verified the degradation of these two contaminants.