Enhanced visible light photocatalytic activity of BiOBr by reactable ionic liquid modification for pollutant degradation.

In this study, hierarchical BiOBr microspheres were synthesized a one-pot solvothermal method in the presence of imidazole ionic liquids. The resultant samples were characterized by XRD, SEM, HRTEM, PL, EPR, EIS and UV-vis absorption spectroscopy. The photoactivity of BiOBr was evaluated by the photocatalytic degradation of methyl orange (MO) and tetracycline hydrochloride. Oxygen vacancies were detected in the system and proven to be correlated with the activity of the catalyst. It was also revealed that BiOBr microspheres prepared by 1-butyl-3-methylimidazolium bromide at 433 K for 8 hours displayed a superior performance compared to the other samples in the degradation of model organic contaminants. After 4.5 hours of reaction, the highest degradation efficiency of 94.0% was achieved by BiOBr-C-Br. Stronger photoluminescence spectral intensities could be obtained as the cationic chain lengths of the ionic liquids reduced gradually. According to our experiments, the better performance of BiOBr-C-Br in the degradation of model pollutants can be attributed to the effect of oxygen vacancies. The findings of our work may have important implications for the design of BiOBr.