Charging Effects on Bonding and Catalyzed Oxidation of CO on Au8 Clusters on MgO

  • Yoon, Bokwon
  • Häkkinen, Hannu
  • Landman, Uzi
  • Wörz, Anke S.
  • Antonietti, Jean-Marie
  • Abbet, Stéphane
  • Judai, Ken
  • Heiz, Ueli

  • 1School of Physics, Georgia Institute of Technology, Atlanta, GA 30332-0430, USA. 2Departement Chemie, Lehrstuhl für Physikalische Chemie I, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany.

*Present address: Department of Physics, Nanoscience Center, Box 35, FIN-40014, University of Jyväskyla, Finland.

†To whom correspondence should be addressed. E-mail: [email protected] (U.L.); [email protected] (U.H.)

Supporting Online Material: www.sciencemag.org/cgi/content/full/307/5708/403/DC1; SOM Text; References

17 August 2004; accepted 30 November 2004

10.1126/science.1104168

Science 307(5708):p 403-407, January 21, 2005.

Gold octamers (Au8) bound to oxygen-vacancy F-center defects on Mg(001) are the smallest clusters to catalyze the low-temperature oxidation of CO to CO2, whereas clusters deposited on close-to-perfect magnesia surfaces remain chemically inert. Charging of the supported clusters plays a key role in promoting their chemical activity. Infrared measurements of the stretch vibration of CO adsorbed on mass-selected gold octamers soft-landed on MgO(001) with coadsorbed O2 show a red shift on an F-center-rich surface with respect to the perfect surface. The experiments agree with quantum ab initio calculations that predict that a red shift of the C-O vibration should arise via electron back-donation to the CO antibonding orbital.

Copyright © 2005 by the American Association for the Advancement of Science
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