Preparation And Characterization Of Cerium Oxide-based Materials And Their Performance

Ceria, as one of the most important rare earth metal oxides, has been widely applied in the field of polishing materials, UV blocking, solid oxide fuel cells and catalysis. The fabrication of the nano-sized ceria or cerium-based oxide and the exploration of the corresponding size-induced or morphology-dependent prosperities have important significance to enhance their application for the unique physical and chemical prosperities induced by the nanostructure.In this paper, we present a facial and template-free glycol solvothermal method to the controlled synthesis of cerium oxide and doped ceria.In glycol, when ammonium ceric nitrate used as precursor, flowerlike ceria fabricated from nanowires was obtained by the self-organization of nanoparticles in view of the morphology evolution observed from the SEM measurement. Ceria with different morphologies can be selectively produced when the concentration of cerium precursor was controlled and the concentration of 40 mmol/L favored the formation of nearly monodisperse spherical nanoparticles. While in the presence of urea and Cerium nitrate or cerium chloride as reactant, the nanostructured ceria with flowerlike morphology was assembled by micropetals and in the case of ammonium ceric nitrate, the micropetals failed to the further assembly.H2-TPR and Raman results show that more oxygen vacancies, higher reducible capacity and more available oxygen species lead to better CO oxidation activity. A 100% conversion was achieved for nanostructured ceria while less than 20% for commercial ceria.The transition metal oxides can be doped into the lattice of ceria and the doped ceria better preserved the original morphology of ceira via a two-step method. The prepared ceria was also an excellent support. When loaded with coppor, CO can be completely transformed to CO₂ at 150℃.