Ordered Mesoporous CeO2 Synthesized by Nanocasting from Cubic Ia3d Mesoporous MCM-48 Silica: Formation, Characterization and Photocatalytic Activity

Ordered nanocrystalline rnesoporous cerium oxide was successfully synthesized using MCM-48 molecular sieves as a hard template. The long-range ordered mesostructure was characterized by low-angle and wide-angle X-ray diffraction (XRD), N-2 adsorption-desorption technique, and transmission electron microscopy (TEM), and the obtained cerium oxide exhibited high similarity to the cubic Ia3d symmetry of the silica template. Due to smaller crystal size, the mesoporous materials have a blue shift in light absorption as compared with nonporous materials. X-ray photoelectron spectrum (XPS) and energy-dispersive X-ray spectrum (EDS) patterns confirm that mesoporous materials possess more surface vacancies than bulk CeO2. Photocatalytic degradation of azodye acid orange 7 under visible light illumination was used as a catalytic test reaction. The activity of mesoporous product in dye decolorization is substantially higher than those for a nonporous sample and TiO2 P25.