title: Electron localization determines defect formation on ceria substrates.
abstract: The high performance of ceria (CeO2) as an oxygen buffer and active support for noble metals in catalysis relies on an efficient supply of lattice oxygen at reaction sites governed by oxygen vacancy formation. We used high-resolution scanning tunneling microscopy and density functional calculations to unravel the local structure of surface and subsurface oxygen vacancies on the (111) surface. Electrons left behind by released oxygen localize on cerium ions. Clusters of more than two vacancies exclusively expose these reduced cerium ions, primarily by including subsurface vacancies, which therefore play a crucial role in the process of vacancy cluster formation. These results have implications for our understanding of oxidation processes on reducible rare-earth oxides.
authors.affiliation: Laboratorio Nazionale Tecnologie Avanzate e Nanoscienza (TASC)-Istituto Nazionale per la Fisica della Materia (INFM), 34012 Trieste, Italy. friedrich.esch@elettra.trieste.it
authors.forename: Friedrich
authors.initials: F
authors.lastname: Esch
authors.forename: Stefano
authors.initials: S
authors.lastname: Fabris
authors.forename: Ling
authors.initials: L
authors.lastname: Zhou
authors.forename: Tiziano
authors.initials: T
authors.lastname: Montini
authors.forename: Cristina
authors.initials: C
authors.lastname: Africh
authors.forename: Paolo
authors.initials: P
authors.lastname: Fornasiero
authors.forename: Giovanni
authors.initials: G
authors.lastname: Comelli
authors.forename: Renzo
authors.initials: R
authors.lastname: Rosei