Effects of the Incorporation of Sc₂O₃ into CeO₂–ZrO₂ Solid Solution: Structural Characterization and in Situ XANES/TPR Study under H₂ Atmosphere

Nanostructured CeO 2 -rich samples cosubstituted with ZrO 2 and Sc 2 O 3 are studied. The effects of the combined additions of both oxides on structural, morphological, and, especially, redox properties of the substituted lattice are assessed. In situ near edge X-ray absorption (XANES) experiments with synchrotron light were performed to study oxygen exchange capacity in a reducing environment for these ternary oxides. Structural characterization revealed that up to 8 at. % Sc was successfully incorporated into the CeO 2 –ZrO 2 lattice without phase segregation. Increased scandia solubility was achieved through a soft chemical route synthesis involving citrate complexation which gave rise to porous powders with crystallite sizes in the nanometer range. In situ XANES experiments in 5 mol % H 2 /He atmosphere demonstrated that adding Sc 3+ to the CeO 2 –ZrO 2 mixed oxide leads to a ternary system (Ce 0.9 Sc x Zr 0.1– x O 2−δ ) with faster reduction kinetics and enhanced reducibility in the whole temperature range analyzed (25–800 °C) compared to both binary materials: Ce 0.9 Zr 0.1 O 2 and Ce 0.9 Sc 0.1 O 1.95 .