Efficient Visible-light Driven Photocatalytic of Ciprofloxacin Oxidation and Cr(VI) Reduction with Sn(II) Doped BiOBr

Bismuth oxyhalides (BiOBr) is a promising photocatalyst for the removal of organic contaminants. However, the efficiency of BiOBr is largely limited by its band structure. Here, we found that Sn2+ doped into BiOBr can modify its band structure, the suitable band structure enables it to have dual catalytic functions of oxidation and reduction with greatly improved photocatalytic performances. Systematic characterizations suggest that Sn2+ cations were homogeneously dispersed into BiOBr. By varying the doping amount of Sn2+, we found that Bi1-xSnx(OBr)1-x/3 (x = 0.2) catalyst exhibited the highest photocatalytic activity. The elimination rates of Cr(VI) (15 mg L-1) and CIP (20 mg L-1) could reach more than 95% in 60 and 40 min under visible light irradiation. In contrast to bare BiOBr, the degradation rate of Cr(VI) and CIP over Bi1-xSnx(OBr)1-x/3 (x = 0.2) increased around 45 and 2 times, respectively. The active substances of the Bi1-xSnx(OBr)1-x/3 catalyst and the environmental impact factors during the catalytic degradation on CIP were determined, and two possible degradation routes were proposed.