Augmented Pairwise Additive Interaction Model for Lateral Adsorbate Interactions: The NO-CO Reaction System on Rh(100) and Rh(111).

Lateral adsorbate interactions have been acknowledged to play an important role in heterogeneous catalytic kinetics. To quantify such energies efficiently and accurately, a lattice-gas-based augmented pairwise additive interaction model was proposed. The model Hamiltonian is defined as the summation over all isolated binding energies and all pairwise interactions, with the pairwise interaction used for each adsorbate pair consisting of the corresponding isolated pairwise interaction and some needed modification terms if the surroundings meet specific conditions. The parameters used in this augmented pairwise additive interaction model for the NO-CO reaction system on Rh(100) and Rh(111) were collected based on density functional theory (DFT) calculations. The reliability of the model was examined by the reproduction of some DFT-based predictions and experimental observations. Results suggest that the lateral interactions on Rh(100) are relatively short range and greatly susceptible to the lateral displacements of adsorbates, whereas on Rh(111), the lateral interactions are relatively long range and the lateral displacements of adsorbates are more limited. In addition, the Brønsted-Evans-Polanyi relations for adsorbate diffusion were constructed and a modification strategy was proposed for certain diffusion processes. This work opens up the possibility of accurate microkinetic modeling for this reaction system with a faithful account of lateral interactions and motivates the extensions to other complex surface systems.