Ultrafast piezo-photocatalytic degradation of organic pollutions by Ag2O/tetrapod-ZnO nanostructures under ultrasonic/UV exposure

Ultrafast degradation of organic pollutions has been realized by the piezo-photocatalytic activity of Ag2O/tetrapod-ZnO nanostructures under ultrasonic/UV exposure. Tetrapod-ZnO (T-ZnO) nanostructures are synthesized in mass production by a thermal evaporation method, and Ag2O nanoparticles are uniformly loaded on the whole surface of T-ZnO nanostructures. Under both ultrasonic and UV exposure, Ag2O/TZnO nanostructures can efficiently co-use the mechanical and UV energy to degrade organic pollutions, and the degradation speed is extraordinarily fast. Taking methylene blue (MB) as an example, Ag2O/TZnO nanostructures (2 g L-1) can completely degrade an MB aqueous solution (5 mg L-1) within similar to 2 min under ultrasonic (200 W) and UV (50 W) exposure. Such a degradation rate is much higher than previous results, and has potential applications in sewage treating techniques at the industrial level. In this process, the piezoelectric field of T-ZnO nanostructures and the build-in electric field of Ag2O/T-ZnO heterojunctions can separate the photogenerated electron-hole pairs, lowering the recombination rate and enhancing the photocatalytic activity. The present results can promote the development of sewage treating techniques for environmental improvement.