Enhanced piezo-photocatalytic performance of ZnO/BNBT-6 heterojunction via piezoelectric effect for degradation of dye wastewater

The combination of mechanical energy and solar energy is considered as an effective strategy to solve energy and environmental problems. Here, we prepare ZnO/(Na_0.5Bi_0.5)_0.94Ba_0.06TiO₃(ZnO/BNBT-6) heterostructure, which significantly enhances the piezo-photocatalytic degradation performance by the piezoelectric effect induced under the built-in electric field. The catalytic oxidation capacity of the ZnO/BNBT-6 heterostructure was significantly improved, and the reaction rate constant can be up to 0.07335 min^-1 under ultrasonic vibration and ultraviolet visible light irradiation, which is much higher than that of photocatalysis and piezocatalysis. This excellent performance occurs because a built-in polarization field is generated inside the BNBT-6 nanorod by ultrasound, which can accelerate effective separation of photogenerated e⁻-h⁺ pairs in BNBT-6 and ZnO, therefore, enhancing the activity of the heterojunction. Finally, a possible piezo-photocatalytic degradation mechanism was proposed based on the free radical trapping experiment and experimental results. This study provides a valuable reference for the design of high efficient piezo-photocatalysts.