Oxygen vacancy formation and migration in Ce(1-x)Zr(x)O2 catalyst: a DFT+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 Ce(1-x)Zr(x)O(2) in a series of Ce/Zr ratios. Substitution of Zr(4+) ion in CeO(2) creates activated oxygen in Ce(1-x)Zr(x)O(2), leading to higher oxygen storage capacity (OCS) compared to CeO(2) 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 Ce(1-x)Zr(x)O(2) materials, especially for 50% Zr-doped ceria. The detailed electronic analysis is also carried out to gain insights into the higher OCS of the Ce(1-x)Zr(x)O(2) catalyst.
Chen
Hsin-Tsung
HT
National Center for High-Performance Computing, No. 28, Nan-Ke Third Road, Hsin-Shi, Tainan 74147, Taiwan. htchen@nchc.org.tw
Chang
Jee-Gong
JG