Tuning electron transfer by crystal facet engineering of BiVO for boosting visible-light driven photocatalytic reduction of bromate.

Removal of bromate (BrO) has gained increasing attention in drinking water treatment process. Photocatalysis technology is an effective strategy for bromate removal. During the photocatalytic reduction of bromate process, the photo-generated electrons are reductive species toward bromate reduction and photo-generated holes responsible for water oxidation. In this study, the monoclinic bismuth vanadate (BiVO) single crystal was developed as a visible photocatalyst for the effective removal of bromate. The as-synthesized BiVO photocatalyst with optimized {010} and {110} facets ratio could achieve almost 100% removal efficiency of BrO driven by visible light with a first-order kinetic constant of 0.0368 min. As demonstrated by the electron scavenger experiment and density functional theory (DFT) calculations, the exposed facets of BiVO should account for the high photocatalytic reduction efficiency. Under visible light illumination, the photo-generated electron and holes were spatially transferred to {010} facets and {110} facets, respectively. The BiVO single crystal photocatalyst may serve as an attractive photocatalyst by virtue of its response to the visible light, spatially charge transfer and separation as well as high photocatalytic activity, which will make the removal of BrO in water much easier, more economical and more sustainable.