Ensemble Effects in Adsorbate–Adsorbate Interactions in Microkinetic Modeling

Adsorbates on a surface
experience lateral interactions
that result
in a distribution of adsorption energies. The adsorbate–adsorbate
interactions are known to affect the kinetics of surface reactions,
which motivates efforts to develop models that accurately account
for the interactions. Here, we use density functional theory (DFT)
calculations combined with Monte Carlo simulations to investigate
how the distribution of adsorbates affects adsorption and desorption
of CO from Pt(111). We find that the mean of the average adsorption
energy determines the adsorption process, whereas the desorption process
can be described by the low energy part of the adsorbate stability
distribution. The simulated results are in very good agreement with
calorimetry and temperature-programmed desorption experiments and
provide a guideline of how to include adsorbate–adsorbate interactions
in DFT-based mean-field kinetic models.