title: Raman analysis of mode softening in nanoparticle CeO(2-δ) and Au-CeO(2-δ) during CO oxidation.
abstract: Oxygen vacancy levels are monitored during the oxidation of CO by CeO(2-δ) nanorods and Au-CeO(2-δ) nanorods, nanocubes, and nanopolyhedra by using Raman scattering. The first-order CeO(2) F(2g) peak near 460 cm(-1) decreases when this reaction is fast (fast reduction and relatively slow reoxidation of the surface), because of the lattice expansion that occurs when Ce(3+) replaces Ce(4+) during oxygen vacancy creation. This shift correlates with reactivity for CO oxidation. Increases in the oxygen deficit δ as large as ~0.04 are measured relative to conditions when the ceria is not reduced.
authors.affiliation: Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA.
authors.forename: Youjin
authors.initials: Y
authors.lastname: Lee
authors.forename: Guanghui
authors.initials: G
authors.lastname: He
authors.forename: Austin J
authors.initials: AJ
authors.lastname: Akey
authors.forename: Rui
authors.initials: R
authors.lastname: Si
authors.forename: Maria
authors.initials: M
authors.lastname: Flytzani-Stephanopoulos
authors.forename: Irving P
authors.initials: IP
authors.lastname: Herman