Surface and Bulk Composition, Structure, and Photocatalytic Activity of Phosphate-Modified TiO₂

Phoshpate-modified titania (P−TiO 2 ) 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−TiO 2 samples. XPS, ICP-AES, and SAXS investigations were additionally performed to further clarify the structural changes of the TiO 2 sample due to phosphate modification. We showed that the phosphate ions reacted with the TiO 2 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−TiO 2 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−TiO 2 samples with optimal phosphate content than it is on Degussa TiO 2 . Phosphate groups bound to the surface of titania are responsible for the enhanced photo-oxidation observed on P−TiO 2 samples.