title: Pd6O4+: an oxidation resistant yet highly catalytically active nano-oxide cluster.
abstract: The palladium oxide cluster Pd(6)O(4)(+) is formed as the sole product upon reaction of a bare palladium cluster Pd(6)(+) with molecular oxygen in an octopole ion trap under multicollision conditions. This oxide cluster is found to be resistant to further oxidation over a large temperature range, and further O(2) molecules merely physisorb on it at cryogenic temperatures. The particular stability of Pd(6)O(4)(+) is confirmed by the observation that the reaction of Pd(7)(+) with O(2) leads to fragmentation resulting in the formation of Pd(6)O(4)(+). However, in an oxygen-rich O(2)/CO mixture, Pd(6)O(4)(+) is identified as the catalytically active species that effectively facilitates the low-temperature oxidation of CO. Gas-phase reaction kinetics measurements in conjunction with first-principles calculations provide detailed molecular level insight into the nano-oxide cluster chemistry and are able to reveal the full catalytic combustion reaction cycle.
authors.affiliation: Institute of Surface Chemistry and Catalysis, University of Ulm, Albert-Einstein-Allee 47, 89069 Ulm, Germany.
authors.forename: Samdra M
authors.initials: SM
authors.lastname: Lang
authors.forename: Irene
authors.initials: I
authors.lastname: Fleischer
authors.forename: Thorsten M
authors.initials: TM
authors.lastname: Bernhardt
authors.forename: Robert N
authors.initials: RN
authors.lastname: Barnett
authors.forename: Uzi
authors.initials: U
authors.lastname: Landman