Impact of oxygen vacancy on piezo-photocatalytic catalytic activity of barium titanate

Piezo-photocatalysis driven by available vibration energy and light irradiation is an attractive strategy to address the environmental issues and energy crisis, which highly relies on the design of high-performance piezoelectric-based catalysts. In this work, photo-responsive piezoelectric barium titanate (BaTiO3) nanoparticles with surface oxygen vacancies have been successfully synthesized and used as the prototype to explore the underlying effects of surface oxygen vacancies on the photocatalysis and piezoelectric catalysis. It is found that the surface oxygen vacancies can efficiently promote the light absorption and charge separation, which, however, slightly impair piezoelectric property, fractionally reducing the piezoelectric catalytic activity. As a result, the surface oxygen vacancies play a double-edged sword role in mediating the photocatalytic and piezoelectric activities. Specifically, the surface oxygen vacancies prompt a 3.5 times enhancement of photocatalytic activity, and cause a 1.5 times reduction of piezoelectric catalytic performance. More importantly, the surface oxygen vacancies display the positive effect on the coupled piezo-photocatalytic catalytic performance, which originates from the balance of two competing effects of surface oxygen vacancies on the photocatalysis and piezoelectric catalysis. This research reveals the influence and mechanism of surface oxygen vacancies on the piezo-photocatalytic activity of BaTiO3.