Unveiling the effect of crystal facets on piezo-photocatalytic activity of BiVO4

In this work, the role of crystal facet in piezo-photocatalysis is systematically investigated through experiments and theoretical calculations. BiVO4 (BVO) with different facets are successfully prepared via a hydrothermal method by tuning pH, and their piezocatalytic, photocatalytic and piezo-photocatalytic activities in degradation of organics are comprehensively evaluated. It demonstrates that BVO with (040) facet not only possesses a narrower bandgap and a higher carrier concentration but also enjoys a better charge separation than that with (110) facet, resulting in a stronger photocatalytic activity. Conversely, the (110) facet can induce a larger internal piezoelectric potential and possess the stronger adsorption activity for reactants than (040) facet, contributing for the improved piezocatalytic performance. As an effective coupling between photocatalysis and piezocatalysis, the piezo-photocatalysis exhibits a much higher performance than the isolated ones. Importantly, the relatively lower photocatalytic efficiency of (110) facet can be improved by its stronger built-in piezoelectric potential, thereby the (110) facet exhibits higher piezo-photocatalytic performance than (040) facet. This work first sheds insights into the facet-activity piezo-photocatalysis, and provides an effective method for developing high-performance catalysts by facet engineering.