Enhanced bacterial disinfection by Bi₂MoO₆-AgBr under visible light irradiation

Bi₂MoO₆-AgBr hybrid photocatalyst was synthesized via a mixed solvothermal-precipitation method. The as-synthesized photocatalysts were well characterized by Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopic (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectra (DRS), as well as photoluminescence spectra (PL). The visible light driven (VLD) disinfection activity of Bi₂MoO₆-AgBr was tested using Escherichia coli as the model bacteria. Complete disinfection of 3×10⁶ CFU mL^-1 viable cell density was observed in 90min under visible light irradiation for Bi₂MoO₆-AgBr with the optimal AgBr amount. Ag⁺ released from the photocatalysts did not affect the inactivation process due to the low concentration. Whereas, photo-generated holes, H₂O₂ and O₂^- were the main active species involved in the photocatalytic disinfection reaction. The presence of O₂ and direct contact between photocatalysts and bacterial cells were found to be indispensable for the cell inactivation. In addition, neutral and slight alkaline conditions was beneficial for the disinfection process.