Preparation of nanosized crystalline TiO_2 particles at low temperature for photocatalysis

摘要

Nanocrystalline titanium dioxide (TiO_2) particles were prepared by a modified alkoxide method under acidic conditions at temperatures ranging from 60 ℃ to 90 ℃. The reaction temperature was used to control the crystalline phase of the TiO_2 particles. At 60 ℃ and 75 ℃ rutile was formed whilst at 90 ℃ anatase and brookite were formed. The photocatalytic activity of the prepared particles was tested for the degradation of sucrose. The photocatalytic activities of the prepared nanosized TiO_2 were compared to those obtained from Degussa P-25 TiO_2 as well as TiO_2 crystalline samples prepared using the conventional sol-gel/heat treatment method. At low organic concentrations, Degussa P-25 exhibited higher photocatalytic behaviour than all the prepared particles while, at high organic concentrations, the nanosized TiO_2 particles prepared at low temperature displayed an activity comparable to Degussa P-25 but much higher than the heat treated sample. The formation of excess intermediates during the degradation of higher sucrose loadings is believed to hinder the photoactivity of Degussa P-25, while the prepared TiO_2 particles are able to maintain their activity for the degradation of the intermediates of sucrose.