Novel Nanocrystalline Ce1−xLaxO2−δ (x = 0.2) Solid Solutions: Structural Characteristics and Catalytic Performance

The catalytic CO oxidation results revealed that nanosized ceria-lanthana (CL) solid solution exhibits superior catalytic performance and thermal stability in comparison to ceria-zirconia (CZ) solid solution. The rationale for excellent catalytic behavior of the CL sample was elucidated from the viewpoint of structure, redox behavior, and bulk oxygen mobility. Accordingly, in this investigation CL solid solution has been synthesized by a modified coprecipitation method, and the structural and redox properties have been deeply investigated employing various characterization techniques, namely, X-ray diffraction (XRD), BET surface area, transmission electron microscopy (TEM), Raman spectroscopy (UV-RS and Vis-RS), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), and temperature programmed reduction (TPR). The catalytic efficiency has been evaluated for oxygen storage/release capacity (OSC) and CO oxidation activity. The analyses of the characterization results provided a deep insight on the physical properties like nanocrystalline nature and surface area, and the chemical properties like oxygen deficiency and reducibility. The lattice parameter of the cubic phase has been observed to increase because of the formation of a solid solution of the type Ce 1− x La x O 2−δ ( x = 0.2) due to partial substitution of La 3+ into CeO 2 lattice. A correlation is found between the concentration of Ce 3+, lattice defects, and oxygen migration rate with the OSC and reducibility. The detailed investigation infers that the CL solid solution exhibits better catalytic properties due to smaller crystallite size, facile reduction, profound bulk oxygen mobility, and enhanced OSC.