Preparation of Co- and Cr-doped mixed crystal TiO2 powders and comparison of the photocatalytic degradation abilities under sunlight irradiation

Abstract

The Co-doped, Cr-doped, and undoped mixed crystal TiO2 powders were prepared by sol–gel and treatment methods and were characterized by thermogravimetric-differential thermal analysis, X-ray powder diffraction, and Fourier transform infrared technologies. And then these three kinds of prepared TiO2 powders were used as catalysts in the degradation of Acid Red B (C.I. Carmosine 14) dye in aqueous solution under sunlight irradiation and their photocatalytic activities were also compared. The results showed that the Co-doped mixed crystal TiO2 powder treatment at 600°C for 3.0 h showed highest photocatalytic activity among three photocatalysts. Apparently, the doped cobalt ions can not only restrain the growth of TiO2 crystallites, which finally decreases the particle size and increase the specific surface area of TiO2 particles, but also trap the photogenerated electrons and restrain the combination of hole-electron pairs. Otherwise, the mixed crystal can enhance the absorption ability for sunlight and cause the separation of holes and electrons. Thus, the prepared Co-doped mixed crystal TiO2 powder is applicable for the treatment of wastewater under sunlight irradiation.