title: In situ time-resolved characterization of Au-CeO2 and AuOx-CeO2 catalysts during the water-gas shift reaction: presence of Au and O vacancies in the active phase.
abstract: Synchrotron-based in situ time-resolved x-ray diffraction and x-ray absorption spectroscopies were used to study the behavior of nanostructured {Au+AuO(x)}-CeO(2) catalysts under the water-gas shift (WGS) reaction. At temperatures above 250 degrees C, a complete AuO(x)-->Au transformation was observed with high catalytic activity. Photoemission results for the oxidation and reduction of Au nanoparticles supported on rough ceria films or a CeO(2)(111) single crystal corroborate that cationic Au(delta+) species cannot be the key sites responsible for the WGS activity at high temperatures. The rate determining steps for the WGS seem to occur at the gold-ceria interface, with the active sites involving small gold clusters (<2 nm) and O vacancies.
authors.affiliation: Department of Chemistry, Brookhaven National Laboratory, Upton, NY 11973, USA. rodrigez@bnl.gov
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: J A
authors.initials: JA
authors.lastname: Rodriguez
authors.forename: J C
authors.initials: JC
authors.lastname: Hanson
authors.forename: M
authors.initials: M
authors.lastname: Pérez
authors.forename: J
authors.initials: J
authors.lastname: Evans