p-n Heterojunction of BiOI/ZnO nanorod arrays for piezo-photocatalytic degradation of bisphenol A in water.

p-n Heterojunctions of BiOI/ZnO nanorod arrays (BiOI/ZnO NRs) were prepared by loading the p-type BiOI nanosheets on the n-type ZnO nanorod arrays for efficient removal of organic contaminants in water during the piezo-photocatalytic degradation. Under concurrent visible-light irradiation and ultrasonic vibration, the bisphenol solution (50 mL, 10 mg/L) could be completely degraded within 30 min by 10 mg of 0.15 BiOI/ZnO NRs. It shows a dramatically-enhanced degradation efficiency under light irradiation and ultrasonic vibration, which is four times as high as that only under light irradiation. The excellent piezo-photocatalytic ability of BiOI/ZnO NRs could be attributed to the piezoelectric effect coupling with photocatalytic process. Under the irradiation of light, the electron-hole pairs were generated in BiOI nanosheets, and the piezoelectric potential is created inside the highly oriented one-dimensional ZnO nanorods by ultrasonic vibration, which can accelerate the migration of photogenerated carriers. It shows a strategy to effectively enhance the photocatalytic activity through utilizing the internal piezoelectric potential, which is generated by the one-dimensional nanorods with piezoelectric properties under ultrasonic vibration. So, it can promote the separation and prolong the lifetime of photogenerated carriers, and result in high-efficient degradation of organic contaminants.