title: Direct Visualization of Catalytically Active Sites at the FeO-Pt(111) Interface.
abstract: Within the area of surface science, one of the "holy grails" is to directly visualize a chemical reaction at the atomic scale. Whereas this goal has been reached by high-resolution scanning tunneling microscopy (STM) in a number of cases for reactions occurring at flat surfaces, such a direct view is often inhibited for reaction occurring at steps and interfaces. Here we have studied the CO oxidation reaction at the interface between ultrathin FeO islands and a Pt(111) support by in situ STM and density functional theory (DFT) calculations. Time-lapsed STM imaging on this inverse model catalyst in O2 and CO environments revealed catalytic activity occurring at the FeO-Pt(111) interface and directly showed that the Fe-edges host the catalytically most active sites for the CO oxidation reaction. This is an important result since previous evidence for the catalytic activity of the FeO-Pt(111) interface is essentially based on averaging techniques in conjunction with DFT calculations. The presented STM results are in accord with DFT+U calculations, in which we compare possible CO oxidation pathways on oxidized Fe-edges and O-edges. We found that the CO oxidation reaction is more favorable on the oxidized Fe-edges, both thermodynamically and kinetically.
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Wilhelmine
authors.initials: W
authors.lastname: Kudernatsch
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Guowen
authors.initials: G
authors.lastname: Peng
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Helene
authors.initials: H
authors.lastname: Zeuthen
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Yunhai
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Lindsay R
authors.initials: LR
authors.lastname: Merte
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Lutz
authors.initials: L
authors.lastname: Lammich
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Besenbacher
authors.affiliation: Department of Chemical and Biological Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
authors.forename: Manos
authors.initials: M
authors.lastname: Mavrikakis
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, Aarhus University , DK-8000 Aarhus C, Denmark.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wendt
keywords: CO oxidation; FeO islands; Pt; active sites; catalysis; density functional theory (DFT); in situ scanning tunneling microscopy (STM)