Study On Visible-light Photocatalytic Performance Of Mesoporous TiO₂ Modified By Ag/AgBr At Lower Temperature

In this paper,the mesoporous Ag/AgBr/TiO₂ nanocomposites were fabricated in a water bath at lower temperatures using the sol-gel method with CTAB or a comb-type polymer as template and the photocatalytic degradation of methylene orange?MO?was using these nanocomposites under visible light.In the first part,the Ag/AgBr/TiO₂ nanocomposite with a plasma effect was prepared with tetrabutyl titanate?TNB?,cetyltrimethyl ammonium bromide?CTAB?and silver nitrate by deposited-photoreduction in low-temperature water bath.The dispersion state of Ag/AgBr was controlled by different prepared conditions.Ag/AgBr/TiO₂ photocatalyst was characterized by X-ray diffraction?XRD?,transmission electron microscopies?TEM?,N₂ sorption analysis?BET?,X-ray photoelectron spectroscopy?XPS?,UV-vis-diffuse reflectance spectroscope?UV-Vis DRS?,electrochemical Impedance Spectroscopy?EIS?,photoluminescence spectroscopy?PL?,et al.The photocatalytic activity of the prepared samples were evaluated by the degradation of methylene orange?MO?under the visible light irradiation.The introduction of Ag/AgBr not only decreased the electron-hole recombination,but also significantly increased the visible light photocatalytic activity of TiO₂.The results showed that the optimal synthesized conditions of Ag/AgBr/TiO₂were determined that the ratio of CTAB to AgNO₃ was 1:1.1 at the bath temperature 70?and the bath time was 8h.In these conditions,the degradation rate of methyl orange can reach 91%under visible-light irradiation.The Ag/AgBr/TiO₂ particles exhibited strong absorption ability in visible-light region because of the plasmon resonance of silver NPs.In the second part,the mesoporous TiO₂ nanocomposites were fabricated in a water bath at lower temperatures using the sol-gel method with a comb-type polymer as template and tetrabutyl titanate as Ti source.The Ag/AgBr/TiO₂ nanocomposites with higher specific surface areas were obtained by the introduction of Ag/AgBr on the surface of the mesoporous TiO₂ using a deposition-precipitation method.The as-prepared nanocomposites were characterized by X-ray diffraction?XRD?,N₂ sorption analysis?BET?,transmission electron microscope?TEM?and UV-vis diffuse reflectance spectroscopy?UV-vis DRS?.The results showed that both the as-prepared TiO₂ and Ag/AgBr/TiO₂ exhibited mesoporous structure.The introduction of Ag/AgBr not only decreased the specific surface area of the mesoporous TiO₂ from 346 m²/g to 253 m²/g,but also significantly increased its visible light photocatalytic activity.The degradation rate of methyl orange under visible light irradiation over Ag/AgBr/TiO₂ was 145 and 60 times of those over the commercial TiO₂ P25 and the mesoporous TiO₂,respectively.