Synergetic piezo-photocatalytic effect in NaNbO3/WO3 photocatalyst for RhB degradation

Improving the separation efficiency of photo-generated charge carriers is an important strategy to enhance the photocatalytic performance. In this paper, the NaNbO3/WO3 composite photocatalyst was prepared via a hydrothermal method, which exhibited a substantial increase in photocatalytic activity through the synergetic effect of visible light irradiation and ultrasound vibration. The XRD, FT-IR, Raman, SEM, XPS, UV–vis DRS, and photoluminescence spectroscopy results indicated that a large number of WO3 particles were tightly attached to the surface of NaNbO3 nanowires in the NaNbO3/WO3 composite catalyst. Under the piezo-photocatalysis condition, the degradation efficiency of Rhodamine B (RhB) by 5 % NaNbO3/WO3 was significantly improved, reaching 73.7 % within 120 min. Meanwhile, the piezo-photocatalytic degradation efficiency of the NaNbO3/WO3 composite catalyst was increased by 30.1 % compared to single photocatalysis, and the corresponding reaction rate constant (K) was 2.23 times than that of single photocatalysis. In addition, quenching tests showed that h+ was the primary active species in piezo-photocatalytic process. The significant enhancement of piezo-photocatalytic performance was attributed to the piezoelectric field caused by the bending deformation of the NaNbO3 nanowires, which was an important driving force for photo-generated charge carrier separation. Furthermore, the production of multiple redox active sites simultaneously improved the photocatalytic performance.