Fabrication of BiOX (X=Cl, Br, and I) nanosheeted films by anodization and their photocatalytic properties

BiOX (X=Cl, Br, and I) nanosheeted films were fabricated by anodization of bismusth foils in the electrolytes containing halide ions. The morphology, crystal structure, and photocatalytic activity of the samples were characterized by scanning electron microscope, X-ray diffractometer and UV-vis spectrophotometer, respectively. The influences of composition and concentration of the electrolyte, applied voltage, reaction time and reaction temperature on the films׳ morphology were studied in detail. Formation mechanism of the nanosheeted films was discussed as well. Results show that the preparation conditions of nanosheeted films differed markedly when X was Cl, Br and I, respectively. The obtained nanosheeted films were of tetragonal structure and possessed obvious photocatalytic activities. The BiOCl nanosheeted films had the best activity in degrading methyl orange solutions and the solutions became almost colorless after irradiation for 6 h under a Xe arc lamp.