title: An Atomic-Scale View of CO and H2 Oxidation on a Pt/Fe3 O4 Model Catalyst.
abstract: Metal-support interactions are frequently invoked to explain the enhanced catalytic activity of metal nanoparticles dispersed over reducible metal oxide supports, yet the atomic-scale mechanisms are rarely known. In this report, scanning tunneling microscopy was used to study a Pt1-6/Fe3O4 model catalyst exposed to CO, H2, O2, and mixtures thereof at 550 K. CO extracts lattice oxygen atoms at the cluster perimeter to form CO2, creating large holes in the metal oxide surface. H2 and O2 dissociate on the metal clusters and spill over onto the support. The former creates surface hydroxy groups, which react with the support, ultimately leading to the desorption of water, while oxygen atoms react with Fe from the bulk to create new Fe3O4(001) islands. The presence of the Pt is crucial because it catalyzes reactions that already occur on the bare iron oxide surface, but only at higher temperatures.
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria).
authors.forename: Roland
authors.initials: R
authors.lastname: Bliem
authors.affiliation: Debye Institute for Nanomaterials, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht (The Netherlands).
authors.forename: Jessi
authors.initials: J
authors.lastname: van der Hoeven
authors.affiliation: Institute of Physical Engineering, Brno University of Technology, 61669 Brno (Czech Republic).|CEITEC BUT, Brno University of Technology, 61669 Brno (Czech Republic).
authors.forename: Adam
authors.initials: A
authors.lastname: Zavodny
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria).
authors.forename: Oscar
authors.initials: O
authors.lastname: Gamba
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria).
authors.forename: Jiri
authors.initials: J
authors.lastname: Pavelec
authors.affiliation: Debye Institute for Nanomaterials, Utrecht University, P.O. Box 80.000, 3508 TA Utrecht (The Netherlands).
authors.forename: Petra E
authors.initials: PE
authors.lastname: de Jongh
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria).
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria).
authors.forename: Ulrike
authors.initials: U
authors.lastname: Diebold
authors.affiliation: Institute for Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10, 1050 Wien (Austria). Parkinson@iap.tuwien.ac.at.
authors.forename: Gareth S
authors.initials: GS
authors.lastname: Parkinson
keywords: Mars-van Krevelen mechanism; metal-support interactions; oxide surfaces; scanning probe microscopy; supported catalysts