Reduced cerium configurations in CeO2/Ag inverse catalysis

Abstract

Inverse catalysts consisting of thin layers of a reducible oxide supported on noble metal surfaces have recently attracted much attention and shown to be competitive with the conventional catalysts, where metal nanoparticles are instead deposited on metal-oxide supports, in terms of their catalytic activity. We present here a computational study based on the density functional theory of the reduction geometries induced on ceria layers by a Ag support and by the creation of oxygen vacancies. We find that electrons are transferred from the Ag support to the ceria layers. These electrons localize at some Cerium sites to form 2D long range ordered patterns of Ce3+ and Ce4+ cations. Depending on their location the oxygen vacancies contribute and modify these patterns. The oxidation state of the cerium atoms affects the catalytic activity of the oxides.