Simple synthesis of BiOAc/BiOBr heterojunction composites for the efficient photocatalytic removal of organic pollutants

Given that the formation of p-n heterojunctions between semiconductors could effectively improve the activities of catalysts, a novel p-n BiOAc/BiOBr heterojunction composite was successfully synthesized. The introduction of BiOAc improved the morphology of the BiOBr and formed flower-like nanostructured BiOAc/BiOBr composites. Rhodamine B (RhB) was degraded by ~98% under 5 W LED light irradiation (λ > 390 nm) within 15 min on 10 wt% BiOAc/BiOBr samples, which was much higher than that on pure BiOBr (~70%). Under the same conditions, 75% and 50% of Ciprofloxacin (CIP) was degraded within 120 min on 10 wt% BiOAc/BiOBr and BiOBr, respectively. This enhanced photocatalytic activity was attributed to the existence of a heterojunction electric field that was formed at the BiOAc/BiOBr interface. The dominant active species in the photocatalytic system were identified as h+ and •O2− via radical trapping experiments and ESR analysis. Finally, a potential photocatalytic mechanism over the BiOAc/BiOBr composites was proposed.