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Rasmus Westerström

Associate senior lecturer

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Structure and catalytic reactivity of Rh oxides

Author

  • Johan Gustafson
  • Rasmus Westerström
  • Andrea Resta
  • Anders Mikkelsen
  • Jesper N Andersen
  • O. Balmes
  • X. Torrelles
  • M. Schmid
  • P. Varga
  • B. Hammer
  • G. Kresse
  • C. J. Baddeley
  • Edvin Lundgren
Show all

Summary, in English

Using a combination of experimental and theoretical techniques, we show that a thin RhO2 surface oxide film forms prior to the bulk Rh2O3 corundum oxide on all close-packed single crystal Rh surfaces. Based on previous reports, we argue that the RhO2 surface oxide also forms on vicinal Rh surfaces as well as on Rh nanoparticles. The detailed structure of this film was previously determined using UHV based techniques and density functional theory. In the present paper, we also examine the structure of the bulk Rh2O3 corundum oxide using surface X-ray diffraction. Being armed with this structural information, we have explored the CO oxidation reaction over Rh(1 1 1), Rh(1 0 0) and Pt25Rh75(1 0 0) at realistic pressures using in situ surface X-ray diffraction and online mass spectrometry. In all three cases we find that an increase of the CO2 production coincides with the formation of the thin RhO2 surface oxide film. In the case of Pt25Rh75(1 0 0), our measurements demonstrate that the formation of bulk Rh2O3 corundum oxide poisons the reaction, and argue that this is also valid for all other Rh surfaces. Our study implies that the CO oxidation reaction over Rh surfaces at realistic conditions is insensitive to the exact Rh substrate orientation, but is rather governed by the formation of a specific surface oxide phase. (C) 2008 Elsevier B.V. All rights reserved.

Department/s

  • Synchrotron Radiation Research

Publishing year

2009

Language

English

Pages

227-235

Publication/Series

Catalysis Today

Volume

145

Issue

3-4

Document type

Conference paper

Publisher

Elsevier

Topic

  • Atom and Molecular Physics and Optics

Keywords

  • surfaces
  • Single crystal
  • In situ
  • Rhodium
  • Surface X-ray diffraction (SXRD)
  • Surface structure

Conference name

Workshop of the European-Synchrotron-Radiation-Facility, 2009

Conference date

2009-02-02 - 2009-02-05

Conference place

Grenoble, France

Status

Published

ISBN/ISSN/Other

  • ISSN: 0920-5861