Enhanced Oxygen Storage Capacity of Porous CeO(2) by Rare Earth Doping

CeO(2) is an important rare earth (RE) oxide and has served as a typical oxygen storage material in practical applications. In the present study, the oxygen storage capacity (OSC) of CeO(2) was enhanced by doping with other rare earth ions (RE, RE = Yb, Y, Sm and La). A series of Undoped and RE–doped CeO(2) with different doping levels were synthesized using a solvothermal method following a subsequent calcination process, in which just Ce(NO(3))(3)∙6H(2)O, RE(NO(3))(3)∙nH(2)O, ethylene glycol and water were used as raw materials. Surprisingly, the Undoped CeO(2) was proved to be a porous material with a multilayered special morphology without any additional templates in this work. The lattice parameters of CeO(2) were refined by the least–squares method with highly pure NaCl as the internal standard for peak position calibrations, and the solubility limits of RE ions into CeO(2) were determined; the amounts of reducible–reoxidizable Ce(n+) ions were estimated by fitting the Ce 3d core–levels XPS spectra; the non–stoichiometric oxygen vacancy (V(O)) defects of CeO(2) were analyzed qualitatively and quantitatively by O 1s XPS fitting and Raman scattering; and the OSC was quantified by the amount of H(2) consumption per gram of CeO(2) based on hydrogen temperature programmed reduction (H(2)–TPR) measurements. The maximum [OSC] of CeO(2) appeared at 5 mol.% Yb–, 4 mol.% Y–, 4 mol.% Sm– and 7 mol.% La–doping with the values of 0.444, 0.387, 0.352 and 0.380 mmol H(2)/g by an increase of 93.04, 68.26, 53.04 and 65.22%. Moreover, the dominant factor for promoting the OSC of RE–doped CeO(2) was analyzed.