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O: Fachverband Oberflächenphysik
O 14: Oxide Surfaces: Adsorption and Reactivity
O 14.5: Vortrag
Montag, 16. März 2015, 16:00–16:15, MA 042
Surface chemistry of magnetite (001) surface: Adsorption of Formic Acid and Methanol. — •Oscar Gamba1, Heshmat Noei2, Jiří Pavelec1, Roland Bliem1, Michael Schmi1, Ulrike Diebold1, Andreas Stierle2, and Gareth Parkinson1 — 1Institute of Applied Physics, Vienna University of Technology, Wien, Austria — 2DESY Nanolab & Physics Department, University of Hamburg, Hamburg, Germany
Understanding the surfaces of metal oxides and their interactions with organic molecules is a crucial aspect in research topics such as catalysis, and environmental science. Formic acid (HCOOH), and methanol (CH3OH), are often used as probe molecules to test the reactivity of metal oxide surfaces (1). Adsorption of both species can be molecular, as in the low temperature regime, but is frequently dissociative on surfaces that expose pairs of undercoordinated cations (2).
In this talk, the study of adsorption of formic acid and methanol on the Fe3O4(001) surface using XPS, LEED, IRRAS, and STM will be described. Both molecules adsorb molecularly at low temperature, and dissociatively at room temperature, yielding adsorbed formate and methoxy species respectively, together with surface hydroxyl groups. Formate adsorbs in a bidentate configuration at regular iron lattice sites producing a (1X1) overlayer. Methoxy adsorption is restricted to step edge and other defect sites where the coordinative undersaturation of the surface atoms is higher.
1.J. M. Vohs, Chemical Reviews 113 (6), 4136-4163 (2012). 2.J. M. Vohs and M. A. Barteau, Surface Science 176 (12), 91-114 (1986).