Surface and bulk composition, structure, and photocatalytic activity of phosphate-modified TiO2

Phoshpate-modified titania (P-TiO2) samples of varying phosphate contents were prepared by the sol-gel method, and the photocatalytic activity was tested in the gas-phase degradation of ethanol at room temperature. DRIFT, UV-vis-DR, N-2 adsorption, and XRD methods were used to characterize the structural properties of the P-TiO2 samples. XPS, ICP-AES, and SAXS investigations were additionally performed to further clarify the structural changes of the TiO2 sample due to phosphate modification. We showed that the phosphate ions reacted with the TiO2 surface and that a new crystalline titanium phosphate phase appeared during the calcination process. It was found that the structural and optical properties of the titania samples are strongly influenced by their phosphate content. The photocatalytic activity of the P-TiO2 was compared with that of Degussa P25 titanium dioxide by ethanol photooxidation in the gas phase. We have shown that total degradation of ethanol is significantly faster on P-TiO2 samples with optimal phosphate content than it is on Degussa TiO2. Phosphate groups bound to the surface of titania are responsible for the enhanced photo-oxidation observed on P-TiO2 samples.