Abstract: Pure TiO² and Co-doped TiO² composite nano-particles with different mix ratios were prepared by  sol-gel method and the prepared samples were characterized by means of XRD and UV-Vis.Photocatalytic degradation of methylene orange (OM) in aqueous solution was used as a probe reaction to evaluate their photocatalytic activity.Influences of different treatment temperatures and doping rates on photocatalystic activity of TiO² were also studied and the best doping rate of 1%(amount-of substance fraction) and best heat treatment temperature of 600 ℃ were obtained.Under the conditions,Co²⁺ dopant greatly restrained TiO² phase transformation,and made the optic response range of TiO² particles expand to the visual light.And Co-doped TiO² had better photocatalystic activity than pure TiO².

Key words: cobalt doping, titana, photocatalytic degradation；methyl orange