Structural Characterization and Catalytic Activity of Ce0.65Zr0.25RE0.1O2-delta Nanocrystalline Powders Synthesized by the Glycine-Nitrate Process

Abstract

In this study, Ce0.66Zr0.25RE0.1O2-delta (RE = Tb, Gd, Eu, Sm, Nd, Pr, and La) solid solutions were successfully prepared by the glycine-nitrate process and tested for CO oxidation activity. The X-ray diffraction results confirmed the formation of complete Ce(0.6)sZr(0.25)RE(0.1)O(2-delta) solid solutions. The Raman spectroscopy measurements suggested the presence of oxygen vacancies due to defective structure formation and further evidenced the formation of solid solution. The high-resolution transmission electron microscopy observations showed the nanocrystalline nature of the solid solutions. From X-ray photoelectron spectroscopy analysis it was revealed that the cerium, terbium, and praseodymium are present in +3 and +4 oxidation states. The UV-vis diffuse reflectance spectroscopy indicated that the Pr3+ ions in the Ce0.65Zr0.25Pr0.1O2-delta system provoked a significant increase in the Ce3+ fraction on the surface. H-2 temperature-programmed reduction measurements showed an enhanced surface reduction at much lower temperatures for Ce0.65Zr0.25Pr0.1O2-delta sample compared to others, indicating increased oxygen mobility in these samples, which enable the enhanced oxygen diffusion at lower temperatures. Significantly high CO oxidation activity is exhibited by Ce0.65Zr0.25Pr0.1O2 solid solution.