Effect of annealing on Photo degradation of Rhodamine 6G using CeO2-SiO2 nanocomposite

Samples of CeO2-SiO2 nanocomposites were prepared using sol-gel method at different annealing temperature. The pure cubic fluorite structure of CeO2 nanocrystal has been achieved at similar to 300 degrees C with a uniform distribution in SiO2 matrix. Structural parameters were confirmed by x-ray diffraction technique. The average nanocrystalline size has been calculated as 0.5, 1.5 and 2.5 nm using Debye-Scherrer formula for annealed samples. The prepared nanocomposite samples have capability to absorb and release oxygen without altering the fluorite structure of ceria. In the present study, we have analyzed that cerium oxide have ability to shift easily between reduced and oxidized states (Ce3+/Ce4+) and to accommodate variable levels of bulk and surface oxygen vacancies. The concentration of the oxygen vacancies decreases with the increase of annealing temperature and corresponding crystallite size. The surface area of annealed samples has also been estimated by Brunauer-Emmett-Teller (BET) equation. The photo catalytic activity was studied through the degradation of Rhodamine 6G in aqueous solution under visible light exposure. As prepared CeO2-SiO2 nanocomposite has the highest photo catalytic efficiency and then it is decreased with annealing temperature.