Layered perovskite piezoelectric Bi3TiNbO9 as a piezo-photocatalyst: Synergistically enhanced catalytic activity and mechanism

Photocatalysis is considered as a green and efficient technology for dealing with water pollution problems, but there exists serious carrier recombination in photocatalysis. Introducing a piezoelectric electric field to reduce carrier recombination and accelerate carrier separation and migration is a recognized as an effective approach, while it remains testing for exploitation for high-performance catalysts with light and stress dual response as well as the coupling catalytic mechanism. In this work, we report a novel layered perovskite structure piezo-photocatalyst Bi3TiNbO9 and conducted an analysis of potential piezo-photocatalytic mechanisms. The piezoelectric force microscopy (PFM) and COMSOL finite element analysis prove that the Bi3TiNbO9 is a piezoelectric with strong piezoelectricity. In the degradation of tetracycline hydrochloride, Bi3TiNbO9 exhibits significantly better piezo-photocatalysis performance compared to piezocatalysis and photocatalysis. It is owing to that the ultrasound results in piezoelectric polarization accompanied by the generation of piezo-potential, which can induce piezocatalysis and facilitate the separation and transfer of photo-generated carriers. Electron paramagnetic resonance (EPR) technique and electrochemical tests are carried out under different excitation sources to identify the dominant active species involved in the reaction and to disclose the origin for the high performance of piezo-photocatalysis from the perspective of carriers. This study adds a new member to the family of piezo-photocatalytic material system, and provides further understanding on the synergistic piezo-photocatalysis mechanism.