Facile synthesis of BiOBr photocatalysts with tunable morphologies and exposed facet ratios by tuning reaction medium for photocatalytic degradation of antibiotics

Crystal facets and morphology are crucial factors governing the photocatalytic performance of BiOBr. However, there remains a lack of rationally designed, facile and effective strategies to fabricate BiOBr photocatalysts with well-defined morphologies and exposed crystal facets. In this study, a series of BiOBr photocatalysts with varying facet exposure ratios were synthesized via a facile polyol-assisted complexation strategy to modulate the proportion of the dominant (010) facets. Introducing polyols profoundly modulates the morphology, size, facet proportions, optical bandgap, and charge carrier separation efficiency of BiOBr. Compared with the sample prepared via a conventional hydrothermal method, all polyol-assisted BiOBr photocatalysts exhibited enhanced photocatalytic activities. Notably, the BiOBr-GL sample synthesized using glycerol as the solvent achieved the highest degradation efficiencies for ciprofloxacin (CIP) and tetracycline (TC), reaching 96.4% and 93.2%, respectively. Furthermore, the catalytic degradation mechanism of BiOBr-GL was elucidated in detail. The outstanding photocatalytic activity of BiOBr-GL is fundamentally attributed to its unique nanoflower-like architecture, highly exposed (010) facets, favorable visible-light responsiveness, and efficient migration of photogenerated charge carriers. This work offers a facile and instructive strategy for the preparation of highly active bismuth oxyhalide catalysts via crystal facet engineering.