Novel preparation method for a new visible light photocatalyst: mesoporous TiO2 supported Ag/AgBr

Abstract

A new method for the preparation of mesoporous TiO2 with a surface deposited with nanoparticles of Ag and AgBr was developed. Cetyltrimethylammonium bromide (CTAB) was used as both a template agent and bromine source in the preparation process of the mesoporous TiO2. Mesoporous TiO2 containing CTAB was synthesized by a sol–gel method, and was dipped into AgNO3 solution to form a mesoporous AgBr/TiO2 nanocomposite. The AgBr/TiO2 nanocomposite was irradiated by visible light to accelerate photolysis of AgBr, forming mesoporous Ag/AgBr/TiO2 photocatalyst. The Ag/AgBr/TiO2 photocatalyst was characterized by small angle X-ray diffraction (SAXRD), wide angle X-ray diffraction (WAXRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and N2 isothermal adsorption–desorption. Ag/AgBr/TiO2 exhibits high photocatalytic activity for the degradation of methyl orange under visible light irradiation. The photocatalytic reaction follows the first-order kinetics and the rate constant (k) for the degradation of methyl orange photocatalyzed by Ag/AgBr/TiO2 is 63.6, 36.1 and 2.7 times that of mesoporous TiO2 (M-TiO2), commercial TiO2 (P-25), and Ag/AgBr/SiO2, respectively. The recycling runs experiment shows that the photocatalytic stability of the Ag/AgBr/TiO2 photocatalyst is excellent. The visible light photocatalytic mechanism of Ag/AgBr/TiO2 is also discussed.