Synthesis of g-C₃N₄/BiOI/BiOBr heterostructures for efficient visible-light-induced photocatalytic and antibacterial activity

Visible-light-driven g-C₃N₄/BiOI/BiOBr composite photocatalysts were successfully synthesized by a facile deposition precipitation method. The as-prepared samples have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and ultraviolet–visible absorption spectroscopy (UV–vis). The photocatalytic experiments indicate that the g-C₃N₄/BiOI/BiOBr composites possess enhanced photocatalytic activity towards the degradation of methyl orange (MO), and killing Escherichia coli. Photoluminescence (PL) spectra reveal that the introduction of g-C₃N₄ could efficiently promote the separation efficiency of photo-induced charge carriers in the composites. The radical trapping experiment and ESR analysis confirmed that the active species ·O₂⁻, h⁺ and ·OH are the reactive oxygen species in the photocatalytic process. Our results suggest that the g-C₃N₄/BiOI/BiOBr composite photocatalysts can be used in water treatment of degrading the organic pollutants and killing the water bacteria at the same time.