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

Piezoelectric polarization can provide a strong driving force to accelerate the separation and migration of photo-generated carriers, enabling more electrons and holes to migrate to the surface of the Bi 3 TiNbO 9 nanosheets . Meanwhile, the piezo-potential will induce the band bending, which can adjust the band structure to enhance the redox abilities of catalyst. • Bi 3 TiNbO 9 nanosheets were synthesized by an one-step hydrothermal method. • Piezocatalytic and piezo-photocatalytic performance of Bi 3 TiNbO 9 were explored. • Piezoelectric polarization accelerates the separation and migration of photocharges. • Bi 3 TiNbO 9 shows universal piezo-photocatalytic degradation performance and excellent durability. 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 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 Bi 3 TiNbO 9 and conducted an analysis of potential piezo-photocatalytic mechanisms. The piezoelectric force microscopy (PFM) and COMSOL finite element analysis prove that the Bi 3 TiNbO 9 is a piezoelectric with strong piezoelectricity. In the degradation of tetracycline hydrochloride, Bi 3 TiNbO 9 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.