Abstract: The atomic structure of the active sites in Cu/CeO₂ catalystsis intimately associated with the copper-ceria interaction. Both the shape of ceria and the loading of copper affect the chemical bonding of copper species on ceria surfaces and the electronic and geometric character of the relevant interfaces. Nanostructured ceria, including particles (polyhedra), rods, and cubes, provides anchoring sites for the copper species. The atomic arrangements and chemical properties of the (111), (110) and (100) facets, preferentially exposed depending on the shape of ceria, govern the copper-ceria interactions and in turn determine their catalytic properties. Also, the metal loading significantly influences the dispersion of copper species on ceria with a specific shape, forming copper layers, clusters, and nanoparticles. Lower copper contents result in copper monolayers and/or bilayers while higher copper loadings lead to multi-layered clusters and faceted particles. The active sites are usually generated via interactions between the copper atoms in the metal species and the oxygen vacancies on ceria, which is closely linked to the number and density of surface oxygen vacancies dominated by the shape of ceria.

Key words: Cu/CeO₂ catalyst, Ceria shape, Oxygen vacancy, Copper particle, Copper-ceria interface, Active site