Structure of pore wall of mesoporous titania with extremely high surface area

摘要

With an extremely large surface area and an amorphous nature, the atomic structure of mesoporous titania can differ in many points from that in all the other titanium oxides. XAFS spectroscopies was applied to investigating the local structure of Ti. The pre-edge peaks of the Ti K edge XANES demonstrated that 5- and 6-fold coordinations of Ti coexist and the population of the latter species is twice as much as the former. The population of 5-fold Ti decreased at 673 K-calcination, accompanied by a considerable decrease of the surface area. The anharmonic pair distribution function was considered in the analysis of EXAFS from Ti-O bond. The Debye temperature of template extracted titania was 213 K, which is considerably lower than before the extraction, suggesting that the micelles filling the pores suppress large vibrations of the Ti-O bond in the pore wall.