Synthesis and Oxygen Storage Capacities of Yttrium-Doped CeO 2 with a Cubic Fluorite Structure.

Doping CeO 2 with Y cations was achieved in this study using three strategies: doping only during the hydrothermal process (H-Y-doped CeO 2 ), doping only during the impregnation process (I-Y-doped CeO 2 ), and doping during both the hydrothermal and impregnation processes (H/I-Y-doped CeO 2 ). During the three synthesis strategies of Y-doped CeO 2 , these Y ions could be incorporated into the CeO 2 lattice in the +3 state while holding the cubic fluorite structure, and no impurity phases were detected. Pure CeO 2 crystal itself contained a certain number of intrinsic V O defects, and Y-doping was beneficial for the creation of extrinsic V O defects. The relative concentrations of V O defects were quantified by the values of A 592 / A 464 obtained from Raman spectra, which were 1.47, 0.93, and 1.16 for the H-Y-, I-Y-, and H/I-Y-doped CeO 2 , respectively, and were higher than that of the undoped one (0.67). Moreover, the OSCs of the three Y-doped CeO 2 were enhanced, and the sequence of OSCs was: H-Y-doped CeO 2 (0.372 mmol/g) > H/I-Y-doped CeO 2 (0.353 mmol/g) > I-Y-doped CeO 2 (0.248 mmol/g) > Undoped CeO 2 (0.153 mmol/g); this result was in good agreement with the Raman spectroscopy results.