Signally enhanced piezo-photocatalysis of Bi0.5Na0.5TiO3/MWCNTs composite for degradation of rhodamine B

Recently, the lead-free piezoelectric material Bi0.5Na0.5TiO3 (BNT) has been adopted for piezo-catalysis and synergistic catalysis, such as piezo-photocatalysis. Nonetheless, the catalytic effect of single BNT is too weak to degrade multifarious contaminants. Here, BNT and multi-walled carbon nanotubes (MWCNTs) composite were prepared and the catalytic performance of BNT was prominently boosted by introducing MWCNTs as the electron capturer. Particularly, the degradation rate of Rhodamine B (RhB, a typical contaminant) could reach 90% within 30 min, with a high rate constant of 0.0805 min-1. The specific degradation pathway of RhB was analyzed. The formation of oxygen vacancies was confirmed by XPS analysis, and the vital role of oxygen vacancies in the separation of photo-generated carriers was elucidated. Meanwhile, the BNT/MWCNTs composites manifested stronger transient current response compared to single BNT under the action of light irradiation and ultrasonic vibration, respectively. According to impedance analysis, the composites exhibited lower carrier transport resistance. Eventually, the mechanism of enhanced piezo-photocatalysis was explained in detail. This study provides an effective route to break the shackle of carrier recombination and speed up the carrier transport in piezo-photocatalytic materials.