Lateral Interactions and Multi-isotherms:  Nitrogen Recombination from Rh(111)

Abstract

Lateral adsorbate-adsorbate interactions result in variation of the desorption rate constants with coverage. This effect can be studied in great detail from the shape of a multi-isotherm. To produce the multi-isotherm, the temperature is increased in a (semi)stepwise fashion to some temperature, followed by maintaining this temperature for a prolonged time. Then, the temperature is stepped to a higher value and held constant at this new temperature. This cycle is continued until all of the adsorbates have desorbed. Using a detailed kinetic Monte Carlo model and an optimization algorithm based on Evolutionary Strategy, we are able to reproduce the shape of the experimentally measured multi-isotherm of nitrogen on Rh(111) and obtain the lateral interactions between the nitrogen atoms.

NH3 Oxidation on Oxygen-Precovered Au(111): A Density Functional Theory Study on Selectivity

“…The range of lateral interactions starts at 0.05 eV in diluted systems (0.25 ML), but when neighbors are present at high coverages a 0.30 eV contribution per occupied nearest neighbor structure can be estimated with respect to low-coverage adsorption energies. This agrees well with the values obtained for NO on Rh(100) and illustrates how DFT results can help in the determination of lateral interactions. , …”

“…This final configuration with the 2 N atoms sitting in neighboring fcc sites is less stable than the long distance N−N configuration by 0.04 eV. This points out that in the low-coverage range (i.e., below 0.25 ML) lateral interactions are small . From the N−N coadsorbed state, the recombination barrier is 0.95 eV.…”

Density Functional Theory and Kinetic Studies of Methanation on Iron Surface

“…Utilizing the activation energies supplied by the DFT calculations for various adsorbed species, the kinetics of CO hydrogenation on the Fe(100) surface was simulated. It has been shown recently by Jansen and co-workers in a surface study of NO on Rh(100) and Rh(111) that lateral interactions play a crucial role in the surface coverage, rates of reactions, and thus the reaction mechanism. − In order to account for the influence of neighboring adsorbates on the barriers of reactions, the current model adopted a p(2 × 2) lattice as one unit of the reaction surface of Fe(100), each of which had four available active sites. The number of such units was determined by the total surface area of the catalyst.…”

Kinetic Monte Carlo Modeling for the NO–CO Reaction Mechanism on Rh(100) and Rh(111)

“…These may lead to deviation from the realistic situation. Other studies mainly focused on part of the reaction processes in this reaction system, like NO dissociation, − N 2 recombination, ,, N 2 O decomposition, − and CO oxidation, , supplying instructive information from various aspects, though the extrapolation of this knowledge into the current more complicated reaction system may need further validation. In general, inspiring kinetic models and results have been reported for this reaction system, but a satisfactory description that is realistic and of details of the NO–CO reaction system at the atomic scale is still lacking.…”