Hydrothermal synthesis of bismuth oxybromide-bismuth oxyiodide composites with high visible light photocatalytic performance for the degradation of CV and phenol

This is the first report on a series of BiOpBrq/BiOmIn heterojunctions that were prepared using controlled hydrothermal methods. The compositions and morphologies of the BiOpBrq/BiOmIn could be controlled by adjusting some growth parameters, including reaction pH value, temperature, time, and KBr/KI molar ratio. The photocatalytic efficiency of the powder suspensions was evaluated by measuring crystal violet (CV) and phenol concentrations. Both the photocatalytic process and the photosensitized process were found to work concurrently. The quenching effects of various scavengers and EPR indicated that the reactive O-2(center dot-) played a major role and (OH)-O-center dot and h(+) played minor roles. The photocatalytic activity of the BiOpBrq/BiOmIn heterojunctons reached the maximum rate constant of 0.5285 (or 0.4713) h(-1), 10 times higher than that of P25-TiO2, 14 times higher than that of BiOBr, and 6 times higher than that of BiOI.