Role of Lattice Distortions in the Oxygen Storage Capacity of Divalently Doped CeO2

The doping of ceria (CeO2) with divalent noble metal ions has been shown to improve the reducibility and enhance the oxygen storage capacity (OSC), although the reasons for this are not well understood. We have examined the interaction of a range of divalent dopants with CeO2 using density functional theory, and found that the dopant preferentially adopts the coordination of its own oxide, instead of the cubic coordination of Ce(IV) in ceria. Depending on the electronic structure of the dopants, the different coordinations can create weakly- or under-coordinated oxygen ions that are more easily removed than in pure CeO2. We have used these insights to identify dopants which will increase the reducability of CeO2, while being economically more viable than the presently used noble metals, and we outline guidelines for the design of improved oxide catalysts.