The BiOBr/PVDF film prepared by in situ deposition and phase transformation has high piezo-photocatalytic performance for efficient degradation of Rh B

BiOBr/PVDF composite films with different precursor doping amounts were successfully prepared by in situ deposition phase conversion technology. The physicochemical properties of the composite films were analyzed in detail, and their piezoelectric-photocatalytic performance was systematically investigated. The experimental results showed that BP-0.8 (with a doping amount of 0.8 mmol for the BiOBr precursor) exhibited the best catalytic performance. Under the synergistic effect of visible light irradiation and ultrasonic vibration, the degradation rate of BP-0.8 for 50 mL of 40 mg/L Rhodamine B (Rh B) solution within 60 min could reach 96.73%, and the apparent reaction rate constant (k) of this sample was 0.06198 min⁻ 1 . It was 3.81 times and 27.06 times that of photocatalysis alone and piezoelectric catalysis alone, respectively. The radical capture experiment proved that the main active groups involved in the reaction were h⁺ and ·OH, and the mechanism of piezoelectric photocatalysis of BiOBr/PVDF composite thin films was proposed. In addition, compared with powder catalysts, flexible BiOBr/PVDF membranes were easier to recycle, did not require complex treatment, and still maintained good catalytic activity after ten cycles of testing. This work demonstrated the contribution of the piezoelectric effect to photocatalytic water purification and provided a promising strategy to utilize solar and mechanical energy.