ZnO/CuO Piezoelectric Nanocatalysts for the Degradation of Organic Pollutants

The p–n heterojunction nanocatalyst was successfully synthesized by decorating the surface of ZnO nanorods with CuO by using a low-temperature synthesis method. It was used as the driving force for the removal of tetracycline (TC) in water with mechanical stirring. Different ratios of ZnO/CuO piezoelectric nanocatalysts were examined. The nanoscale ZnO/CuO catalyst achieved a 98% removal rate of TC in water after 120 min. The main active species for TC degradation were identified as hydroxyl radicals (^•OH) and superoxide radicals (^•O_2^–) by quenching experiments. The piezoelectric current generated by ZnO/CuO-1.5 was found to be 3.1 and 6.2 times higher than those of pure ZnO and CuO, respectively, due to the formation of a p–n heterojunction structure and built-in electric field situation. The facile and low-temperature synthesis process of the ZnO/CuO nanocatalyst with superior removal rates provides practical support for large-scale application in wastewater treatment.