Highly synergistic and polarized KNbO3/WO3 heterojunction for piezo-photocatalytic degradation of organic pollutant

The superior piezo-photocatalytic performances of KNbO3-based materials were achieved by the enhanced photo-induced carrier separation and migration based on the effective strategies of heterojunction construction and polarization engineering. A KNbO3/WO3 type-II heterojunction was fabricated by an impregnation-calcination method, and its outstanding piezo-photocatalytic performance was demonstrated. Compared to individual KNbO3 and WO3, KNbO3/WO3 composites exhibited better degradation performance for RhB solution under visible light irradiation, and the degradation rate of 30%KNbO3/WO3 composite for RhB solution was 98% within 80 min (its reaction rate constant k was 0.03894 min−1). Inspiringly, the polarized 30%KNbO3/WO3 composite degraded RhB solution completely within 60 min under visible light irradiation with auxiliary ultrasonic activation, and its reaction rate constant was up to 0.0612 min−1 (3.35 times that of individual KNbO3). The synergistic effects of heterojunction construction, polarization engineering, and ultrasonic vibration in KNbO3/WO3 composite were confirmed, and the multi-electric fields in polarized KNbO3/WO3 heterojunction significantly enhanced carrier separation, thus promoting piezo-photocatalysis. This work proposes an important strategy for designing multi-electric field-driven ferroelectric-based heterojunction photocatalysts.