The main factors influencing the O vacancy formation on the Ir doped ceria surface: A DFT+U study

The effects of Ir doping on the oxygen vacancy formation energy have been investigated using the DFT+U method, i.e., first-principles density functional theory calculations with the inclusion of the on-site Coulomb interaction. The main factors influencing the reducibility of Ir-doped ceria are studied carefully. It is found that, although the Ir doping induces gap states (MIGS) as do other noble metals (Pd, Pt, Rh), the structural relaxation (instead of the electronic structure relaxation) is the main factor responsible for the decrease of the oxygen vacancy formation energy, i.e., the Ir doping makes structural distortions much more exothermic for the reduced ceria.