title: CO bond cleavage on supported nano-gold during low temperature oxidation.
abstract: The oxidation of CO by Au/Fe(2)O(3) and Au/ZnO catalysts is compared in the very early stages of the reaction using a temporal analysis of products (TAP) reactor. For Au/Fe(2)O(3) pre-dosing the catalyst with (18)O labelled water gives an unexpected evolution order for the labelled CO(2) product with the C(18)O(2) emerging first, whereas no temporal differentiation is found for Au/ZnO. High pressure XPS experiments are then used to show that CO bond cleavage does occur for model catalysts consisting of Au particles deposited on iron oxide films but not when deposited on ZnO films. DFT calculations, show that this observation requires carbon monoxide to dissociate in such a way that cleavage of the CO bond occurs along with dynamically co-adsorbed oxygen so that the overall process of Au oxidation and CO dissociation is energetically favourable. Our results show that for Au/Fe(2)O(3) there is a pathway for CO oxidation that involves atomic C and O surface species which operates along side the bicarbonate mechanism that is widely discussed in the literature. However, this minor pathway is absent for Au/ZnO.
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. carley@cardiff.ac.uk
authors.forename: Albert F
authors.initials: AF
authors.lastname: Carley
authors.forename: David J
authors.initials: DJ
authors.lastname: Morgan
authors.forename: Nianxue
authors.initials: N
authors.lastname: Song
authors.forename: M Wyn
authors.initials: MW
authors.lastname: Roberts
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Taylor
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Bartley
authors.forename: David J
authors.initials: DJ
authors.lastname: Willock
authors.forename: Kara L
authors.initials: KL
authors.lastname: Howard
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Hutchings
mesh_terms: D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D005290:Ferric Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011312:Pressure; D011789:Quantum Theory; D013696:Temperature
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide; D006046:Gold; D002248:Carbon Monoxide