Photocatalytic activity, surface area and phase modification of mesoporous SiO2-TiO2 prepared by a one-step hydrothermal procedure

A one-step hydrothermal synthesis process was developed to prepare ordered mesoporous titania-silica materials by using TEOS and TTIP as silica and titania sources, respectively, as well as P123 as a structure-directing agent in acidic conditions. The synthesized materials were hydrothermally treated at various temperatures (70, 100 and 130 °C) and subsequently calcined at 600, 800 and 1000 °C. Small-angle X-ray scattering (SAXS), Field Emission Scanning Electron Microscopy (FESEM), Wide angle X-ray diffraction (WAXRD), Fourier transformed infrared spectroscopy (FTIR) and N2 adsorption-desorption experiments have been used to characterize the mesoporous materials, which were subsequently evaluated in terms of photocatalytic efficiency. The results show that hydrothermal and calcination temperatures can change surface area, phase composition as well as degree of crystallinity dramatically resulting in varying photocatalytic performance. Although higher hydrothermal and calcination temperatures will result in lower surface area, a higher degree of crystallinity can be achieved which lead to improved photocatalytic properties. Very high calcination temperatures (1000 °C) sharply reduce surface areas in the systems resulting in inhibiting photocatalytic efficiency.