Getting Insights into the Influence of Crystal Plane Effect of Shaped Ceria on Its Catalytic Performances

Abstract

Ceria nanoparticles with rodlike (ceria-rod), octahedral (ceria-octahedron), and cubic (ceria-cube) morphologies and similar crystallite dimensions have been synthesized. Transmission electron microscopy results revealed that ceria-octahedra and ceria-cubes are well-faceted, mainly enclosed with {111} and {100} facets, respectively. On the contrary, ceria-rods are not well-faceted. By CO adsorption, in situ Fourier transform infrared, and 17O solid-state NMR (ssNMR) experiments on H217O-enriched ceria, it is shown that the adsorption behavior of CO/H2O is highly crystal-plane-selective. These results are well-supported by surface-enhanced dynamic nuclear polarization 17O ssNMR. A correlation between the formation of oxygen vacancies (isolated vacancies and vacancy clusters) and the surface properties of ceria is proposed.