Role of surface peroxo and superoxo species in the low-temperature oxygen buffering of ceria: Density functional theory calculations

Reversible oxygen release makes ceria (CeO2) among the most efficient oxide supports for low-temperature oxidation reactions. A clear identification of the species responsible for this oxygen buffering is still missing since only indirect information is available. We present a systematic study of O adsorbates on the most stable ceria surfaces based on density functional theory calculations. The results rationalize the experimental findings supporting the interpretation that superoxide species are the key factors in promoting low-temperature oxidation reactions on ceria. The high reactivity of nanocrystalline ceria is explained in terms of the surface selectivity towards superoxide adsorption.