Exceptions to the d-Band Model of Chemisorption On Metal Surfaces: The Dominant Role of Repulsion Between Adsorbate States and Metal d-States

Tuesday, November 9, 2010: 1:33 PM
Grand Ballroom B (Hilton)
Hongliang Xin and Suljo Linic, Chemical Engineering, The University of Michigan, Ann Arbor, MI

Developing predictive models of chemisorption on metal surfaces is critical for the understanding of surface chemical reactions. It has been shown that the d-band model of chemisorption, developed by Hammer and NÝrskov, can predict the trends in chemisorption energies of various adsorbates on metal surfaces. The model correlates the central moment of the d-band projected on surface atoms (d-band center referenced to the Fermi level) with the surface reactivity. It has been used successfully to design novel metal surfaces for various catalytic reactions. In general, for a given adsorption geometry adsorbates bind to the surface of transition or noble metals more strongly if the d-band center of the surface atom is higher in energies.

In this presentation, we show that there is a family of adsorbate-substrate systems that does not follow the trends in adsorption energies predicted by the d-band model. A physically transparent model is used to analyze this phenomenon. We found that these adsorbate-substrate pairs are characterized by the repulsive interaction of the substrate d-band with the renormalized adsorbate states. The exceptions to the d-band model are mainly associated with the adsorbates having almost completely filled valence shell, and the substrates with nearly fully occupied d-band, i.e., OH, F or Cl adsorption on metals and alloys characterized by d9 or d10 substrate surface atoms.

Extended Abstract: File Not Uploaded
See more of this Session: Computational Catalysis II
See more of this Group/Topical: Catalysis and Reaction Engineering Division