Facile synthesis of BiOCl/BiOBr heterojunctions via anion exchange reactions

BiOCl/BiOBr heterojunctions were prepared through the reaction of pre-synthesized BiOCl nanosheets and KBr solution. The anion exchange reaction kinetics can be easily controlled by synergistically adjusting the temperature, reaction time and reactant (KBr solution) concentration. As a result, the phase transition from parent BiOCl to Br-doped BiOCl or BiOCl/BiOBr heterojunctions or Cl-doped BiOBr was readily achieved. The BiOCl/BiOBr heterojunction prepared with the lowest energy consumption exhibited superior photocatalytic performance compared to the parent BiOCl due to its improved light absorption and charge separation efficiency. This work is expected to boost the development of various bismuth oxide halide-based heterojunctions.