An accessible, template-free process to fabricate bimodal mesoporous TiO₂/I₂ composite nanocrystallites was developed by using tetrabutylorthotitanate [TiO(C₄H₉)₄, TBOT] and iodine hydrosol as precursor by hydrolysis precipitation method. The samples were characterized by XRD, TEM, BET, UV-Vis-DRS and FT-IR, respectively. The relation of the heat treatment temperatures and the photocatalysis activity of M-I₂-TiO₂ were also studied. The photocatalytic activity of samples was evaluated by degradation of methylene blue (MB) as target pollutant. The results show that the bimodal mesoporous structured M-I₂-TiO₂ exhibited stronger absorption in visible light region. The specific surface area of the bimodal mesoporous I₂-doped TiO₂ thermal treatment in air at 300 ℃ exceeded 227.6 m²/g, and that of the samples thermal treatment in air at 600 ℃ still have 111.8 m²/g, which indicated the samples have relative high thermal stability. The TiO₂/I₂ composite sample thermal treatment at 400 ℃ manifested the highest photocatalytic activity for photodecomposition of MB solution compared with thermal treatment at other temperatures, the uncomposite TiO₂ and Degussa P-25 under the irradiation of visible-light. Little difference of the activity was observed between the samples used for 6 times.

Key words: TiO₂, I₂, mesoporous, composite, photocatalytic