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

Abstract

This is the first report on a series of BiO_pBr_q/BiO_mI_n heterojunctions that were prepared using controlled hydrothermal methods. The compositions and morphologies of the BiO_pBr_q/BiO_mI_n 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 O₂˙⁻ played a major role and ˙OH and h⁺ played minor roles. The photocatalytic activity of the BiO_pBr_q/BiO_mI_n 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.