Shape impact of nanostructured ceria on the dispersion of Pd species

Abstract

The shape impact of nanostructured ceria on the dispersion of Pd species was investigated by analyzing the atomic configuration and the bonding environment of Pd species over spherical and cubic ceria particles, using STEM and XPS. Amorphous Pd particles of about 2.0 nm, with a substantial amount of tiny Pd species, dispersed on spherical ceria, primarily due to the enriched surface oxygen vacancies that bonded the Pd species tightly. While faceted Pd particles of about 2.9 nm located on cubic ceria with distinct interfaces where Pd atoms embedded into the ceria lattice. The crystalline Pd particles on ceria cubes were highly active and stable for methane combustion that occurred on the metal surface via a facile PdO/Pd redox cycle; while the amorphous Pd particles on spherical ceria particles were featured by a significantly higher activity and stability towards CO oxidation, where the Pd-ceria interface served as the active sites.