Tuning oxygen vacancies in Bi4Ti3O12 nanosheets to boost piezo-photocatalytic activity

Piezo-photocatalysis has emerged as a promising strategy to address environmental pollution and the fastgrowing energy shortage. Unfortunately, current efficiencies of piezo-photocatalysts are still far from ideal, and improving their catalytic efficiency remains challenging. In this paper, we introduce oxygen vacancies (OVs) in Bi4Ti3O12 (BIT) nanosheets to boost their piezo-photocatalytic performance. Compared to pristine BIT nanosheets, BIT with an optimized OV concentration exhibit excellent piezo-photocatalytic activity, with an enhancement of 2.2 times the degradation rate constant (k = 0.214 min-1) for Rhodamine B (RhB). The effect of OVs on the adsorption energy and Bader charges was also investigated using density functional theory (DFT) calculations, which shed light on the underlying mechanism that improves the piezo-photocatalytic process in the presence of OVs. Specifically, the introduction of OVs increases the adsorption energy and Bader charges, resulting in an enhancement of charge transfer between O2/H2O and BIT, thus facilitating the catalytic process. This study provides a deeper understanding into the regulation mechanism of OV enhanced piezo-photocatalytic activity and opens new avenues for designing high-performance piezo-photocatalysts.