Solvothermal synthesis of flower-like BiOBr microspheres with highly visible-light photocatalytic performances

Hierarchical flower-like BiOBr microspheres assembled with nanosheets were synthesized via solvothermal method with both two-component solvent (ethylene glycol and isopropanol) and CTAB surfactant. The growth of BiOBr crystal was significantly influenced by the concentration of ethylene glycol and isopropanol in two-component solvent, the amount of CTAB surfactant and the solvothermal time. According to the photodegradation of rhodamine B (RhB) under visible-light irradiations, the high photocatalytic activity of hierarchical flower-like BiOBr microspheres could be ascribed to the enhanced visible-light absorbance via the light multi-reflections, the efficient separation of photo-generated electrons and holes, the high crystallization and the large surface area. The main active species during the photocatalytic reaction was determined as O2− radical by additionally dissolving the trapping agent in the solution. Meanwhile, BiOBr microspheres also exhibited the excellent durability owing to the stable crystal phase and microsphere morphology.

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► Hierarchical flower-like BiOBr microspheres assembled with nanosheets are prepared by solvothermal process in two-component solvent.
► The growth of BiOBr crystal is controlled by the ratio of ethylene glycol and isopropanol, the amount of CTAB surfactant and the solvothermal time.
► High visible photoactivity is due to strong light absorbance via light multi-reflections and efficient separation of photo-induced charges.
► The O2− radical is the main active species during the photocatalytic reaction.
► The durability of BiOBr photocatalyst is owing to the stable crystal phase and microsphere morphology.