Structural Characterization and Catalytic Activity of Nanosized Ceria−Terbia Solid Solutions

Structural characteristics and catalytic activity of nanosized ceria−terbia mixed oxides have been investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ion scattering spectroscopy, temperature-programmed reduction/oxidation, and Brunauer−Emmett−Teller surface area techniques. The catalytic usefulness has been evaluated for oxygen storage-release capacity (OSC) and CO oxidation activity. The XRD and TEM results suggest that the crystallite sizes of these nano-oxides are in the range 5−12 nm within the investigated temperature range of 773−1073 K. The mixed oxide solid solutions adopted a fluorite-type structure and exhibited cell parameters with respect to Vegard’s rule. The XPS measurements revealed that both cerium and terbium are in 3+ and 4+ oxidation states, 4+ being dominant in both cases. The reduction temperature of the Ce−Tb oxide is observed to be lower than that of the pure ceria and exhibited better redox properties due to the formation of solid solution. The OSC is substantially higher for the mixed oxide, and the presence of oxygen vacancies favored better CO oxidation activity. The nanosized ceria−terbia mixed oxide is also found to be thermally quite stable and capable of manifesting redox behavior after severe heat treatment.