关键词: 溶胶凝胶法, 二氧化钛, 光催化, 钼, 复合催化剂, n-n 结

Abstract: Mo-doped TiO₂ photocatalysts (Mo-TiO₂) were prepared by the traditional sol-gel method using (NH₄)₆Mo₇O₂₄?4H₂O and tetrabutyl titanate (Ti(OC₄H₉)₄) as the raw materials. TiO₂/Mo-TiO₂ composite photocatalysts were prepared by mixing TiO₂ sol with sol-gel derived Mo-TiO₂ powder followed by drying and calcination. The samples were used as catalysts for methyl orange photodegradation in aqueous suspension under UV irradiation, which was used as a probe reaction. X-ray diffraction patterns showed that particles were in the form of anatase and there was no change in crystal structure except a slight variation in crystallite size. The photocatalytic activity of the Mo-TiO₂ photocatalysts was lower than that of undoped TiO₂, and the photodegradation rate decreased with an increase in the level of molybdenum doped (on TiO₂). The reduced activity can be explained by the fact that dopants act more as recombination centers than as trap sites for charge transfer at the interface, especially for the samples with higher molybdenum ion dopant concentration. The TiO₂/Mo-TiO₂ composite photocatalysts have the n-n heterojunction and have a higher photocatalytic destruction rate than the Mo-TiO₂ photocatalysts and undoped TiO₂, which is mainly ascribed to the electrostatic-field-driven electron-hole separation in the TiO₂/Mo-TiO₂ composite photocatalysts. The best TiO₂/Mo-TiO₂ composite with TiO₂:2mol% Mo-TiO₂ mass ratio of 10:1 shows 1.57 times the photocatalytic activity of undoped TiO₂.

Key words: sol-gel method, titania, photocatalysis, molybdenum, composite photocatalyst, n-n heterojunction