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.