Oxygen vacancy formation and migration in Ce1-xZrxO2 catalyst: A DFT plus U calculation

Spin-polarized density functional theory with the inclusion of on-site Coulomb correction (DFT+U) calculation is carried out to study the oxygen vacancy and migration of Ce1-xZrxO2 in a series of Ce/Zr ratios. Substitution of Zr4+ ion in CeO2 creates activated oxygen in Ce1-xZrxO2, leading to higher oxygen storage capacity (OCS) compared to CeO2 due to its structural and electronic modifications. It is found that the oxygen vacancy formation energy (E-f) is lowered even by small amounts of zirconia; the oxide with a content of 50% zirconia exhibits the lowest E-f and the best OCS. This indicates that the O vacancy is most easily created near the Zr centers. In addition, the activation energy calculations for oxygen vacancy migration around Zr dopant show facile oxygen migration through the Ce1-xZrxO2 materials, especially for 50% Zr-doped ceria. The detailed electronic analysis is also carried out to gain insights into the higher OCS of the Ce1-xZrxO2 catalyst. (dC) 2010 American Institute of Physics. [doi:10.1063/1.3429314]