Synthesis of BiOBr microspheres with ethanol as self-template and solvent with controllable morphology and photocatalytic activity

Flower-like bismuth oxybromide (BiOBr) microspheres with highly controllable morphology and photocatalytic activity were facilely synthesized in ethanol using Bi(NO3)(3)center dot 5H(2)O and NaBr. The effects of solvothermal conditions on the morphology and composition were investigated and a mechanism for the microsphere formation was proposed. The temperature and pH of the solvothermal reaction had little effect on morphology but a large effect on visible light photocatalytic activity, which was attributed to changes in the facet intensity ratio, I-110/102. Microspheres prepared at 140 degrees C and pH = 7 had the highest I-110/102 ratio and degraded Rhodamine B (RhB) more rapidly than other BiOBr preparations. The (110) plane has surface Bi3+ sites that coordinate with the carboxylate anion of RhB, thus increasing adsorption but also a stronger internal electric field (IEF) that increases e(-).h(+) separation efficiency. These findings provide a better understanding of the effects of solvothermal conditions on the crystal growth and activity of semiconductor photocatalysts.