Pure TiO₂ and Si-doped TiO₂ fibers were prepared by a sol-gel method combined with vapor activation. The structural parameters and surface morphology were characterized by the techniques such as TG-DSC, XRD, FT-IR, UV-Vis-DRS, N₂ absorption-desorption and SEM. The photocatalytic degradation of X-3B in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The results indicate that compared with pure TiO₂, the sample prepared with a proper dopant of Si is a TiO₂ long fiber with an abundant mesoporous structure, which not only possesses excellent thermal stability and crystal stability, but also has much higher photocatalytic activities. The results also indicate that the anatase phase can be maintained even after calcination at 900 ℃. The sample has the largest specific surface area, pore volume and the best photocatalytic activity when the molar ratio of Si/Ti is 0.15. Under optimum condition, 99.6% of X-3B was degraded after irradiation within 75 min under UV-light.

Key words: sol-gel method, Si doping; TiO₂ fiber, photocatalytic activity