Facet-dependent performance of BiOBr for photocatalytic reduction of Cr(vi)

Hexavalent chromium Cr(VI) is one of the forms of chromium that poses a health risk to humans because of its high acute toxicity and carcinogenic activity. Trivalent chromium Cr(III) is much less toxic and could be easily removed from wastewater as a solid by alkalinication and precipitation. Thus, developing effective technologies capable of reducing Cr(VI) to Cr(III) is of great importance for the treatment of wastewater. Visible light driven photocatalytic reduction as a promising method to achieve this purpose has attracted extensive attention worldwide. Bismuth oxybromide BiOBr has proven itself as a kind of novel visible-light photocatalyst because the separation of photoinduced electrons and holes could be promoted by its internal static electric elds between the positive [Bi2O2] slabs and the anionic bromine layers. Li synthesized 3D owerlike BiOBr nanostructures with an excellent removal capacity and fast adsorption rate for Cr(VI). Lin obtained BiOBr nanocrystals with {001} and {010} dominant facets by hydrothermal method for degrading 2,4-dichlorophenol under UV light. Zhang prepared nanosheets dominated with {102} as well as with {001} facets and compared their catalytic performance for the degradation of rhodamine B (RhB) under visible light irradiation. Chen reported ultrathin BiOBr nanosheets with the {001} facet percentage of 98% showing higher photocatalytic activity than BiOBr nanoplates (63% {001}). In this work, the facetdependent photocatalytic activities of BiOBr with {001} and