Dramatically improved piezo-photocatalytic activity in PVDF@Bi2MoO6/BiOBr composite films via constructing built-in polarization field in heterojunctions

The coupling effect of piezo-photocatalytic technology is well demonstrated as a promising strategy for effective degradation of organic pollutants. However, the catalytic efficiency is dramatically limited by the undesirable neutralization of photogenerated electron-hole pairs. Herein, PVDF@Bi 2 MoO 6 /BiOBr heterojunction was designed elaborately to boosting their piezo-photocatalytic activity by built-in polarization field and controlled carrier transfer. The composite film presents excellent degradation performance of methyl orange (MO, 15 mg/L) (98.99%, 120 min) under the simultaneous ultrasonic vibration and visible light irradiation, which is around 2 and 3.1 times than that of individual piezoelectric and photocatalytic process. The improved piezo-photocatalytic capability could be attributed to the enhanced built-in piezoelectric field that generated by the vibration of p-type BiOBr nanosheets . The construction of piezoelectric polarization reduces the recombination efficiency of photogenerated carriers at the p-n heterojunction interface, thereby dramatically improving the catalytic efficiency. This work proposes and demonstrates the very positive role of dual piezoelectricity in modulating the photocatalytic efficiency in semiconductors, which provides a new paradigm for the further development of highly-efficient piezo-photocatalysts to be applied in environmental purification and wastewater treatment.