Hierarchical organization and catalytic activity of high-surface-area mesoporous ceria microspheres prepared via hydrothermal routes.

Mesoporous Ce(OH)CO(3) microspheres with flowerlike three-dimensional (3D) hierarchical structure were successfully synthesized via different hydrothermal systems, including glucose/acrylic acid, fructose/acrylic acid, glucose/propanoic acid, and glucose/n-butylamine systems. After Ce(OH)CO(3) microspheres were calcined, mesoporous CeO(2) microspheres with the same flowerlike morphology as Ce(OH)CO(3) microspheres were obtained. Especially, flowerlike CeO(2) microspheres prepared via the glucose/acrylic acid system are composed of many interconnected mesoporous petal-like nanosheets with thicknesses of 40-60 nm and have high surface area (211 m(2) g(-1)), large pore volume (0.32 cm(3) g(-1)), and narrow pore size distribution ( approximately 3.8 nm in diameter). A possible formation mechanism of Ce(OH)CO(3) microspheres is proposed: the large N-containing organic compounds in situ produced in the above reaction systems played a crucial role in controlling the assembly of Ce(OH)CO(3) building blocks into the flowerlike Ce(OH)CO(3) microspheres. For trichloroethylene combustion, flowerlike CeO(2) microspheres were found to exhibit much higher catalytic activity than general CeO(2) prepared with the conventional methods and the T(10%) and T(90%) were as low as 100 and 204 degrees C, respectively.