Facet-dependent photocatalytic activities of BiOBr explored through pattern illumination time-resolved phase microscopy

Abstract

This study presents a detailed investigation into the photocatalytic properties of facet-engineered bismuth oxybromide (BiOBr) using the pattern illumination time-resolved phase microscopy (PI-PM) technique. BiOBr, recognized for its excellent visible-light photocatalytic capabilities, was synthesized with controlled facet exposure to enhance its reactivity and efficiency in degrading organic pollutants. The experimental focus was on assessing the facet-dependent behavior of photo-excited charge carriers within BiOBr under various scavenger conditions. The PI-PM method allowed for the direct imaging of dynamic charge carrier processes at the microscale, offering information on the active charge carrier types (electrons and holes) on the photocatalyst surface. Detailed analyses when exposed to scavengers revealed distinct behaviors across different facets (001, 010, and 102). Key findings include the identification of dominant charge carriers responsible for the enhanced photocatalytic activity of different facets. For instance, the (010) facet showed a pronounced reactivity of holes, whereas the (102) facet was predominantly active via electron-mediated processes. This facet-specific activity underlines the importance of surface properties in optimizing photocatalytic efficiency. Through the application of PI-PM, this research not only provides a deeper understanding of the mechanistic pathways in photocatalysis but also demonstrates the critical role of surface facets in determining the overall performance of BiOBr as a photocatalyst.