Effect of Dopants on the Energy of Oxygen-Vacancy Formation at the Surface of Ceria: Local or Global?

TitleEffect of Dopants on the Energy of Oxygen-Vacancy Formation at the Surface of Ceria: Local or Global?
Publication TypeJournal Article
Year of Publication2011
AuthorsHu Z, Metiu H
JournalJournal of Physical Chemistry C
Volume115
Issue36
Start Page17898
Pagination17898–17909
Date Published09/2011
ISSN1932-7447
KeywordsCNSI, CSC, DOE, Metiu
Abstract

Doping of oxides is used to modify their catalytic properties. The question we address here is whether a dopant affects only the oxygen atom next to it or also the ones further away. We find that low-valence dopants (Na and Li dopants in MgO and La and Y dopants in CeO2) have both a long-range and a short-range effect. In contrast, Pt, Ru, Zr, Ta, Mo, and W dopants in CeO2(111) affect only the oxygen atoms next to them. Furthermore, these dopants lower the energy of making an oxygen vacancy next to them by roughly the same amount. This is puzzling because these dopants have vastly different dopant?oxygen bond strength in their own oxide. By analyzing the electronic structure of the doped oxide and the changes caused by vacancy formation, we suggest that they have similar effects on vacancy formation energy because when they dope ceria, they become tetravalent, just like the Ce atom they replace. Doping of oxides is used to modify their catalytic properties. The question we address here is whether a dopant affects only the oxygen atom next to it or also the ones further away. We find that low-valence dopants (Na and Li dopants in MgO and La and Y dopants in CeO2) have both a long-range and a short-range effect. In contrast, Pt, Ru, Zr, Ta, Mo, and W dopants in CeO2(111) affect only the oxygen atoms next to them. Furthermore, these dopants lower the energy of making an oxygen vacancy next to them by roughly the same amount. This is puzzling because these dopants have vastly different dopant?oxygen bond strength in their own oxide. By analyzing the electronic structure of the doped oxide and the changes caused by vacancy formation, we suggest that they have similar effects on vacancy formation energy because when they dope ceria, they become tetravalent, just like the Ce atom they replace.

URLhttp://dx.doi.org/10.1021/jp205432r
DOI10.1021/jp205432r
Grant: 
CSC