title: Atmospheric pressure X-ray photoelectron spectroscopy apparatus: Bridging the pressure gap.
abstract: One of the main goals in catalysis is the characterization of solid/gas interfaces in a reaction environment. The electronic structure and chemical composition of surfaces become heavily influenced by the surrounding environment. However, the lack of surface sensitive techniques that are able to monitor these modifications under high pressure conditions hinders the understanding of such processes. This limitation is known throughout the community as the "pressure gap." We have developed a novel experimental setup that provides chemical information on a molecular level under atmospheric pressure and in presence of reactive gases and at elevated temperatures. This approach is based on separating the vacuum environment from the high-pressure environment by a silicon nitride grid-that contains an array of micrometer-sized holes-coated with a bilayer of graphene. Using this configuration, we have investigated the local electronic structure of catalysts by means of photoelectron spectroscopy and in presence of gases at 1 atm. The reaction products were monitored online by mass spectrometry and gas chromatography. The successful operation of this setup was demonstrated with three different examples: the oxidation/reduction reaction of iridium (noble metal) and copper (transition metal) nanoparticles and with the hydrogenation of propyne on Pd black catalyst (powder).
authors.affiliation: Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr 45470, Germany.
authors.forename: J J
authors.initials: JJ
authors.lastname: Velasco-Vélez
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Pfeifer
authors.affiliation: Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr 45470, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hävecker
authors.affiliation: Engineering Department, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.affiliation: Graphenea, San Sebastian 20018, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Centeno
authors.affiliation: Graphenea, San Sebastian 20018, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Zurutuza
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Algara-Siller
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Stotz
authors.affiliation: Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr 45470, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Skorupska
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Teschner
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Kube
authors.affiliation: Engineering Department, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Braeuninger-Weimer
authors.affiliation: Engineering Department, University of Cambridge, Cambridge CB3 0FA, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Hofmann
authors.affiliation: Department of Heterogeneous Reactions, Max Planck Institute for Chemical Energy Conversion, Mülheim an der Ruhr 45470, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Schlögl
authors.affiliation: Department of Inorganic Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin 14195, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Knop-Gericke