Iron-doped titania powders prepared by a sol-gel method. Part II: Photocatalytic properties

摘要

Samples of iron-doped titania containing different amounts of Fe (0.5-5wt%) prepared from TiCl_4 and Fe(III) acetylacetonate by a sol-gel method were tested as photocatalysts under near-UV irradiation for EDTA oxidation and for Cr(VI) reduction. Their efficiency has been compared with specimens precpared by impregnation of TiO_2 (Degussa P-25) with iron nitrate or iron acetylacetonate and found to be less active in both redox systems, in spite of the favorable structural properties. The preservation of the P-25 structure in samples prepared by impregnation and a larger amount of defects provided by the preparation technique, acting as recombination centers, seem to be the most important factors affecting the activity. The addition of EDTA highly increases the rate of Cr(VI) reduction, the influence being remarkable in all iron-doped samples.