Enhanced piezo-photocatalytic performance by piezoelectric and visible light photoexcitation coupling through piezoelectric Na0.5Bi0.5TiO3 micron crystals

The unique piezoelectric potential of piezoelectrics could lead to performance gains for electrochemical catalysis. Here, a cuboid-like Na0.5Bi0.5TiO3 (NBTO) piezoelectric micron crystal was synthesized by a hydrothermal process. The piezocatalytic and visible light assisted piezo-photocatalytic activities of NBTO were investigated. Surprisingly, under ultrasonic vibration and visible light irradiation, the NBTO exhibited four times faster degradation rate than that under ultrasonic vibration only, although the NBTO doesn't absorb visible light. An efficient coupling between piezoelectric effect and visible light photoexcitation in NBTO was directly demonstrated. The improved piezo-photocatalytic performance is attributed to the piezoelectric potential and the decrease of bandgap of NBTO micron crystal due to strain induced by ultrasonic vibration. A new fundamental mechanism for the improved degradation of organic dye has been proposed for piezoelectric and photoexcitation coupling. This work extends the application of wide band gap piezoelectric materials in the visible light area.