ZnO/SnS Heterojunctions for Superior Piezophotocatalytic Degradation of Tetracycline Hydrochloride

As an emerging environmental purification material, piezoelectric photocatalysts can significantly enhance catalytic performance through the coupling of mechanical stress and light energy. In this study, ZnO nanorods were grown on the surface of SnS microdisks to successfully construct ZnO/SnS heterojunction composite materials. This material exhibited excellent piezoelectric photocatalytic degradation activity toward tetracycline hydrochloride under simulated sunlight irradiation. The reaction rate constant of the optimal sample ZS-0.05 was 4.68 times and 16.4 times that of pure ZnO and pure SnS, respectively. In the experiment of simultaneous application of light and ultrasonic vibration, the piezoelectric photocatalytic efficiency of ZS-0.05 was significantly higher than that of the single photocatalytic or piezoelectric catalytic process, with a synergy factor of 1.36, demonstrating a significant synergistic enhancement effect. This performance improvement mainly originated from the synergistic effect between the built-in electric field at the heterojunction interface and the piezoelectric field generated by the piezoelectric material under stress, which jointly promoted the efficient separation and migration of photogenerated electron–hole pairs. This study provides an idea for the development of efficient piezoelectric photocatalysts and can be used for the solar-mechanical energy-driven degradation of organic pollutants in water.