Z-scheme ZnSnO3/Bi2WO6 with synergistic polarized electric field for efficient removal of diclofenac

The built-in electric field induced by piezoelectric effect for suppressing the electron-hole recombination has gained substantial attention recently. In this study, a novel Z-scheme ZnSnO3/Bi2WO6 (ZSO/BWO) piezo-photocatalyst with synergistic polarized electric field was synthesized by a simple impregnation method. The optimized 1% ZSO/BWO shows high piezo-photodegradation efficiency (99.9%, 60 min) and mineralization (42%, 60 min) of diclofenac (DCF) under the synergistic action of ultrasound and light, far exceeding that under sole ultrasound or illumination. The remarkable enhanced piezo-photocatalytic activity of ZSO/BWO composite was attributed to the increased absorption, improved charge transfer, Z-scheme heterojunction, and tight surface contact between ZSO and BWO. Moreover, the Z-scheme mechanism of ZSO/BWO composites is studied in depth and confirmed by the free radical capture experiment and electron spin resonance technology. In addition, the corresponding intermediates of DCF degradation and the possible degradation pathways that were proposed on ZSO/BWO composites were analyzed by liquid chromatography-mass spectrometry and DFT. This work offers an efficient approach for constructing and preparing the highly efficient piezo-photocatalysts for converting solar and mechanical vibration energies.