Apatite-coated Ag/AgBr/TiO2 visible-light photocatalyst for destruction of bacteria

Apatite-coated Ag/AgBr/TiO2 was prepared by deposition of Ag as novel metal to generate electron-hole pairs by extending the excitation wavelength to the visible-light region, AgBr, and hydroxy apatite as photosensitive material and adsorption bioceramic, respectively. The energy dispersive X-ray spectrometry clearly showed the presence of Ti, Ag, Ca, and P elements on the surface of catalyst. The bactericidal experiments in dark media indicated that only the novel catalyst shows inhibiting growth of bacteria in this case. A transmission electron microscopy image illustrated that catalyst nanoparticles adhere to the outer membrane of the cell and act as an inhibitor to the nourishment of bacteria from aqueous media. The novel catalyst also showed higher photocatalytic activity compared to Ag/AgBr/TiO2 photocatalyst under visible-light irradiation. The inactivation of E. coli is due to the ability of the catalyst to adhere to the outer cell in addition to destruction of the cell wall by various reactive species.