The Co-doped TiO2nano-powders were prepared by the sol-gel method, and their photocatalytic activities were measured by the degradation of phenol under different light resources(UV and visible). The structures of the powders were also studied through XRD, EFSEM, UV-DRS, and XPS, and the relationship between their structures and photocatalytic activities was analyzed. The results showed that a part of Co2+ions have doped into TiO2lattice successfully and can promote the phase transformation from rutile to anatase, and the others have formed Co3O4and loaded on the surface of the powder. Thep-njunction is probable to be formed between Co3O4and TiO2. These two changes of the structures enhance the photocatalitic activity of the catalyst obviously and the photon excited wavelength of the Co-TiO2powder is broadened to visible light region. When the Co2+doped concentration is 1.0% and the calcination temperature is 773 K, the content of anatase phase in Co-TiO2reaches 70.6%, and the BET surface area is 28.4 m2/g, which represented the best catalytic activity in all samples. The degradation efficiency of phenol in 2 h is 97.7% under UV and 52.3% under visible light irradiation, respectively.
