The effects of hydrothermal temperature on structural and photocatalytic properties of ordered large pore size TiO_2-SiO_2 mesostructured composite

摘要

Ordered TiO_2-SiO_2 mesoporous materials with BJH pore diameters in the range from 12 to 15 nm were synthesized by a one-step hydrothermal synthesis method. In this route, tetraethoxysilane (TEOS) and titanium tetraisopropoxide (TTIP) in a low pH solution were used as SiO_2 and TiO_2 precursor, respectively with P123 as a template and hexane as a micelle expander in the presence of NH_4F. In this work, we show the effect of different hydrothermal temperatures (70 °C and 130 °C) on pore structure and photocatalytic efficiency of the materials prepared. The synthesized materials were characterized by small-angle X-ray scattering (SAXS), N_2 adsorption-desorption experiments, X ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The method could produce ordered mesoporous structure with uniform pore size of 12-15 nm and high specific surface areas Sbet up to 431 m~2 /g. The photocatalytic activity of the samples was evaluated by degradation ofMBunderUVlight irradiation and results showed these mesostructure materials have much higher photocatalytic efficiency in comparison with commercial P25 titania. The results also show that for materials synthesized using higher hydrothermal temperature (130 °C) resulting in increased in photocatalytic activity due to higher formation of anatase phase and more open channels by comparison with lower hydrothermal treatment (70 °C).