High temperature stable mesoporous anatase TiO2 photocatalyst achieved by silica addition

An aqueous sol–gel method was developed to synthesize a high temperature stable anatase titania photocatalyst by doping with silica. Doping was achieved in titania by the addition of silica sol prepared from tetra ethyl orthosilicate (TEOS). 1, 2, 5 and 15 mol% silica–titania mixed oxide were prepared and characterised by X-ray diffraction, Raman spectroscopy, surface area analysis and diffuse reflectance spectra. Fully anatase phase was obtained at 1000 °C by the addition of 15 mol% silica. The 15Si–Ti (15 denotes mol% of silica) had a specific surface area of 187.3 m2/g at 500 °C and it retains a value of 93.0 m2/g at 800 °C, whereas the undoped one shows 48.7 m2/g at 500 °C and zero value at 800 °C. Moreover, the 15Si–Ti composition retains the pore diameter in the mesoporous range (4.6 nm) at this high temperature of 800 °C. The photocatalytic analysis showed that the system with silica added possessed a higher activity than pure titania. The 15Si–Ti sample calcined at 800 °C decolourised the methylene blue dye within 30 min (rate constant 0.084 min−1), whereas the undoped sample decolourised the dye after 180 min (rate constant 0.018 min−1). The present method of preparation offers the advantages of inexpensive precursor, homogeneous distribution of the dopant over titania at nano-level and enables control over the powder characteristics of titania.

Graphical abstractAn aqueous sol–gel method was developed to synthesize the high temperature stable mesoporous anatase titania photocatalyst by doping with silica. Fully anatase phase was obtained at 900 and 1000 °C by the addition of 15 mol% silica. The photocatalytic study showed that 15 mol% sample calcined at 800 °C has a rate constant of 0.084 min−1, whereas the undoped sample shows only 0.022 min−1. Figure optionsDownload full-size imageDownload as PowerPoint slide