Synthesis and characterisation of fluorinated TiO2 microspheres with novel structure by sonochemical–microwave hydrothermal treatment

Abstract

A sonochemical–microwave hydrothermal method for preparing fluorinated mesoporous TiO2 microspheres was developed. Fabrication of mesoporous TiO2 and doping of fluorine were achieved by sonication and then hydrothermal treatment of a solution containing TiO2 precursor sol and sodium fluoride. The average diameter of as synthesised TiO2 microspheres was ∼500 nm. Since the sodium fluoride was doped, rod-like grains (12±0·5 nm) and microporous structure (∼10 nm) formed on the surface, he roughness was clearly increased, and the microspheres look like waxberries. UV-vis absorption spectra showed that samples within the wavelength range from 0 to 300 nm show strong UV absorption and 10 nm BM-shift, which was highly related to its microstructures. The TEM and high resolution TEM results showed a novel mechanism for fluorinated TiO2 microsphere formation, i.e. its rod-assembled mesoporous microstructures related to the absorption of water molecules on the surface of the microspheres.