Enhanced piezo-photocatalytic activity of Bi₂MoO₆ nanosheets: Theory and experimental studies

Stress-induced polarization is deemed to be an important avenue for enhancing photocatalytic activity of photocatalysts, which has drawn considerable attention recently. In this report, we have experimentally and theoretically studied the piezoelectricity-enhanced photocatalytic activity and involved mechanism of Bi2MoO6 nanosheets derived via a hydrothermal synthesis route. Simulated sunlight, ultrasonic and both of them were used to drive the photocatalysis, piezocatalysis and piezo-photocatalysis, respectively. It is demonstrated that, for degradation of various organic dyes and antibiotics, the Bi2MoO6 nanosheets manifest a piezo-photocatalytic activity obviously larger than single photocatalytic activity and piezocatalytic activity with synergistic factor SF > 1. The piezoelectricity in the Bi2MoO6 nanosheets and its enhanced photocatalytic mechanism were elucidated through density functional theory (DFT) calculations combined with finite-element method (FEM) simulations. Additionally, taking the typical organic dye - methylene blue (MB) as an example, we have also investigated the effects of various factors on its degradation efficiency, degradation pathways and mechanism, as well as toxic assessment of degradation by-products.