Abstract:
Nanocrystalline sol-gel derived titania doped with ceria (1, 2, 5 and 10-mole%) has been prepared from titanyl oxysulphate. The titania doped with 5-mole% CeO2 after calcining to 500 degrees C, possesses specific surface area of 97 m(2)g(-1) and has anatase phase stability up to 900 degrees C. Moreover it retains a surface area of 37 m(2) g(-1) at 700 degrees C. In comparison, the undoped calcined material has anatase stability only up to 700 degrees C and specific surface area only 48 m(2) g(-1) and 6 m(2) g(-1) at 500 degrees C and 700 degrees C, respectively. The diffuse reflectance spectra show that, as the cerium content increases, the absorption undergoes a red shift and reaches the visible range. The exceptionally high phase stability, crystallinity and high surface area are due to the extremely fine particle size and effective doping achieved by the specific synthesis method. The results based on X-ray diffraction, specific surface area and diffuse reflectance spectra indicated that the maximum threshold limit of doping is up to a value of 5-mole%.
