Degradation of Rhodamine B via piezoelectric photocatalyst Bi2WO6 responding to visible light and ultrasound: performance and mechanism

At present, the visible light (Vis) catalytic oxidation, as a wastewater treatment approach without secondary pollution, has captured the interest of many researchers. However, the efficiency of visible photocatalysis still needs to be continuously improved. In this study, a piezoelectric photocatalyst Bi 2 WO 6 (BWO) responding to both Vis and ultrasound (US) was prepared, characterized, and employed to treat Rhodamine B (RhB) in water. The removal efficiencies of RhB under different systems (Vis/BWO, US/BWO, (Vis + US)/BWO) were investigated and the reuse capacity of BWO were examined. Moreover, the piezoelectric photocatalytic mechanism of (Vis + US)/BWO system on RhB removal was analyzed. The results exhibited that the prepared Bi 2 WO 6 possessed excellent photoresponsive and piezoresponsive properties, and the removal and mineralization of RhB could reach 100% and 77.2% within 60 min, respectively. Under the combined effect of photocatalysis and piezoelectricity, the superoxide radicals, hydroxyl radicals, and photogenerated holes produced, which were responsible for the degradation of RhB in (Vis + US)/BWO system. Graphical Abstract