Biobrni1-N Solid Solutions As Versatile Photooxidation Catalysts For Phenolics And Endocrine Disrupting Chemicals

A novel family of visible-light-sensitive photocatalysts, bismuth oxyhalide solid solutions (BiOBrnI1-n, n = 0-1), was synthesized by a nonaqueous solvothermal method. The bismuth oxyhalides crystallized in individually separated platelets which aggregated into microspheres, allowing for efficient light capture. By increasing the Br/ I ratio, the band gap of BiOBrnI1-n could be tuned from 1.95-2.95 eV. The material with the composition BiOBr0.75I0.25 exhibited the best photoactivity. It catalysed the degradation of p-cresol under visible light at a rate 31times that of pure BiOBr and 1.7-times that of BiOI. BiOBr0.75I0.25 proved to be a versatile photocatalyst for the degradation of a wide range of substituted alkyl phenols and endocrine disrupting chemicals (EDCs). Total organic carbon in the water was reduced to 10-33 % at > 99 % degradation efficiency. The excellent performance was attributed to a matching bandgap, balance between light absorption and redox potential, and efficient charge separation. Recyclability testing showed that BiOBr0.75I0.25 maintained its high activity even after three cycles of p-cresol photodegradation.