Sn2+ reduction to synthesis of the Mo doped hollow hierarchical Bi/BiOBr microspheres for efficient ciprofloxacin degradation under visible light

Abstract

In this study, the Mo-doped hollow hierarchical Bi/BiOBr microspheres are prepared by the solvothermal method with the Sn2+ as reductant. The prepared composites show a good degradation effect for ciprofloxacin (CIP) under visible light. Especially, the BSM-22 composite show the best photocatalytic activity, with the apparent rate constant k as high as 0.03014 min−1, which is 26.9 times that of the pure BiOBr. It is assumed that the introduction of Sn2+ facilitate the formation of hollow hierarchical microspheres structure of BiOBr microspheres and the appearance of metallic Bi on the surfaces. Therefore, the transfer and separation efficiency of photogenerated charges is increased in the composites. Impressive, benefit from the microtopography of the hollow structure, the specific surface area of the BSM-22 (53.476 m2/g) is 21.76 times than that of the BiOBr (2.458 m2/g). The doping of Mo reduces the band gap of BiOBr (exactly from 2.61 to 1.96 eV) and broaden the photoabsorption region. Therefore, the photocatalytic activity of the Mo-doped Bi/BiOBr microspheres are heavily improved in dealing with different kinds of antibiotic molecules. More importantly, these results show that the design strategies of heteroatom doping, metal bismuth production, and morphology control of the bismuth oxybromide composite can greatly improve the visible-light catalytic activity.