Reactivity of diatomic molecules on Cu(100)

M. A. Van Daelen, M. Neurock, R. A. Van Santen

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31 Scopus citations

Abstract

The reactivity of the diatomic molecules O2, N2, CO and NO on Cu(100) has been studied on cluster models using first principles density functional calculations. For each molecule the dissociation was studied at top, bridge and hollow surface sites. The barriers for dissociation on the energetically most favorable reaction pathways were ordered as O2 < N2, with the N2 and CO barriers high enough to preclude dissociation at moderate operating conditions. The recombination barriers were ordered as CO < NO < N2 < O2. These trends were found to be in good agreement with the experiment and they can be explained in terms of the bonding characteristics and the underlying electronic structure for each molecule. In the case of O2 the dissociation was found to be preceded by a weakly adsorbed state where O2 is lying parallel to the surface. O2 dissociation was favored over a hollow surface site. NO, CO and N2 showed a slight preference for dissociation over the bridge site. An alternative mechanism was found for NO dissociation whereby the NO species goes through a bent adsorbed state in a hollow site and then dissociates over the neighboring bridge of metal atoms. For O2 and NO we calculated for the lowest energy reaction paths the pre-exponential factors for dissociation and recombination using transition state theory. These were 1013 and 5 × 1012, respectively, both in qualitative agreement with the experiment.

Original languageEnglish (US)
Pages (from-to)247-260
Number of pages14
JournalSurface Science
Volume417
Issue number2-3
DOIs
StatePublished - Nov 20 1998

Keywords

  • Copper surfaces
  • Density functional theory
  • Metal catalysis
  • Reaction rates
  • Transition states

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