title: Reverse Water-Gas Shift or Sabatier Methanation on Ni(110)? Stable Surface Species at Near-Ambient Pressure.
abstract: The interaction of CO, CO2, CO + H2, CO2 + H2, and CO + CO2 + H2 with the nickel (110) single crystal termination has been investigated at 10(-1) mbar in situ as a function of the surface temperature in the 300-525 K range by means of infrared-visible sum frequency generation (IR-vis SFG) vibrational spectroscopy and by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS). Several stable surface species have been observed and identified. Besides atomic carbon and precursors for graphenic C phases, five nonequivalent CO species have been distinguished, evidencing the role of coadsorption effects with H and C atoms, of H-induced activation of CO, and of surface reconstruction. At low temperature, carbonate species produced by the interaction of CO2 with atomic oxygen, which stems from the dissociation of CO2 into CO + O, are found on the surface. A metastable activated CO2(-) species is also detected, being at the same time a precursor state toward dissociation into CO and O in the reverse water-gas shift mechanism and a reactive species that undergoes direct conversion in the Sabatier methanation process. Finally, the stability of ethylidyne is deduced on the basis of our spectroscopic observations.
authors.affiliation: Physics Department, University of Trieste , via Valerio 2, I-34127 Trieste, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Roiaz
authors.affiliation: Physics Department, University of Trieste , via Valerio 2, I-34127 Trieste, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Monachino
authors.affiliation: Physics Department, University of Trieste , via Valerio 2, I-34127 Trieste, Italy.|IOM-CNR Laboratorio TASC, Area Science Park , S.S. 14 km 163.5, I-34149 Basovizza (Trieste), Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Dri
authors.affiliation: Abteilung Anorganische Chemie, Fritz-Haber Institut der Max-Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Mark
authors.initials: M
authors.lastname: Greiner
authors.affiliation: Abteilung Anorganische Chemie, Fritz-Haber Institut der Max-Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Knop-Gericke
authors.affiliation: Abteilung Anorganische Chemie, Fritz-Haber Institut der Max-Planck Gesellschaft , Faradayweg 4-6, 14195 Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Schlögl
authors.affiliation: Physics Department, University of Trieste , via Valerio 2, I-34127 Trieste, Italy.|IOM-CNR Laboratorio TASC, Area Science Park , S.S. 14 km 163.5, I-34149 Basovizza (Trieste), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Comelli
authors.affiliation: Physics Department, University of Trieste , via Valerio 2, I-34127 Trieste, Italy.|IOM-CNR Laboratorio TASC, Area Science Park , S.S. 14 km 163.5, I-34149 Basovizza (Trieste), Italy.
authors.forename: Erik
authors.initials: E
authors.lastname: Vesselli