Synthesis of functionalized mesoporous TiO2 molecular sieves and their application in photocatalysis

Functionalized mesoporous TiO2 molecular sieves were prepared by treating ordered mesoporous TiO2 with phosphoric acid or ammonium sulfate at high temperature. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption–desorption measurement, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrometer (FT-IR). The photocatalytic activity of the samples was evaluated by photocatalytic decomposition of bromomethane (CH3Br) in air. Results revealed that the functionalized TiO2 samples preserved ordered mesostructure and exhibited enhanced physicochemical properties. The photocatalytic activity of the functionalized mesoporous TiO2 sample was about three times higher than that of the pure mesoporous TiO2. The concentrations of phosphoric acid and ammonium sulfate solutions used for the functionalization of TiO2 greatly influenced the photocatalytic activity of the resultants materials. The optimal concentrations of phosphoric acid and ammonium sulfate solutions were 0.05 and 0.10 M, respectively. The enhanced photocatalytic performance of the functionalized mesoporous TiO2 could be attributed to large specific surface area, high hydroxyl density, and enhanced surface chemical state.