BiOBr photocatalysts with tunable exposing proportion of {001} facets: Combustion synthesis, characterization, and high visible-light photocatalytic properties

•We present a combustion approach to synthesize BiOBr photocatalysts for organic dye decomposition.•The BiOBr nanosheets possessing pure tetragonal BiOBr phase with high ratio of {001} facets exposure were obtained.•By changing the added amount of ammonium bromide, the thickness of BiOBr nanosheets with the exposing proportion of {001} facets can be controlled.•BiOBr with the thinnest sheets exhibited the best photocatalytic activity of Rhodamine B under visible-light irradiation.•We present a plausible crystal growth mechanism to explain the reliance of BiOBr nanosheets thickness on the added amount of ammonium bromide.

BiOBr photocatalysts were synthesized by the combustion method. The BiOBr nanosheets possessing pure tetragonal BiOBr phase with high ratio of {001} facets exposure were obtained. The thickness of BiOBr nanosheets, in other words, the exposing proportion of {001} facets can be modulated through changing the added amount of ammonium bromide. The band gap energy of BiOBr was increased with larger exposing proportion of {001} facets. BiOBr with the thinest sheets exhibited the best photocatalytic activity of Rhodamine B under visible-light irradiation. To the end, the corresponding plausible growth mechanism of BiOBr was presented.