Enhanced visible-light photocatalytic performances of ZnO through loading AgI and coupling piezo-photocatalysis

Highlights: • AgI/ZnO heterostructures were synthesized by a simple chemical deposition. • High degradation efficiency and excellent reusing activity was obtained. • It is due to rapid separation of dominant e⁻ and h⁺ from AgI/ZnO heterostructure. • Degradation time was greatly shortened under ultrasonic vibration. -- Abstract: AgI nanoparticles decorated with ZnO flower-like composites were successfully synthesized via citric acid-induced hydrothermal reaction and subsequent chemical deposition in the presence of ammonium hydroxide. The effects of AgI-loading content and the piezoelectric effect of ZnO were investigated using different technologies. The crystal structures and optical and photocatalytic properties revealed that the AgI particles were successfully loaded on the flower-like ZnO through the directed diffusion process of charge-induced deposition. Results also showed that the band gap of the AgI/ZnO composite located between those of the ZnO and the AgI, which was consistent with the theoretic simulation. The degradation rate of RhB induced by the AgI/ZnO composites was three times larger than that of AgI, and the heterojunction exhibited high photocatalytic degradation efficiency for MO and TC. Besides, the photodegradation efficiency remained high after six times. Radical scavenger experiments implied that e⁻ and h⁺ played important roles in the photocatalytic process. The photodegradation time was considerably shortened while maintaining increased degradation efficiency after adding ultrasonic vibration due to the rapid separation of carriers caused by the piezo-photocatalysis coupling effect.