Coverage Effects on Reaction and Activation Energies at Metal Surfaces

6 COVERAGE EFFECTS ON REACTION AND ACTIVATION ENERGIES AT METAL SURFACES 

The density of adsorbates on a surface is termed the adsorbate coverage, usually written as a fractional number of adsorbates per surface atom. Within this definition, coverage of one adsorbate per surface atom is equivalent to one monolayer (ML). (As an aside, some care must be taken in comparing to experimentally inferred coverages, which are often reported as fractional number relative to the experimentally accessible maximum. The experimentally accessible maximum is not necessarily one adsorbate per surface atom.) All examples given to this point were computed in 3x3 surface supercells, implying an effective coverage of 1/9 ML in the case of 

FIGURE 6.10 High -coverage model showing NO molecules and vacant sites for adsorption and reaction. Pd, N, and O denote palladium, nitrogen and oxygen atoms respectively. (See insert for color representation of the figure.) 

Reaction Reaction energy on dilute surface, A E/teV) rxn Reaction energy with 9/16 ML NO spectators A /(eV) ixn Activation energy on dilute surface A /(eV) Activation energy with 9/16 ML NO spectators EJ(cV) 

COMPUTATIONAL SCREENING FOR IMPROVED HETEROGENEOUS CATALYSTS AND ELECTROCATALYSTS 

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