Date of Original Version
An analysis is given of diffusion-influenced surface reactions using models similar to those used in solution kinetics. It is shown that a pure two-dimensional model of surface reactions yields no steady state rate constant. By incorporation of adsorption and desorption processes the deficiencies in the two-dimensional results are eliminated. Expressions are derived for diffusion-controlled and diffusion-influenced rate constants for surface reactions. Expressions are also derived for the activation energies of these surface reactions. It is shown that the activation energy for diffusion-controlled reactions wiII approximately be given by the activation energy for surface diffusion. Bounding expressions are developed for the activation energy for diffusion-influenced reactions. Comparisons are made betweeen Langmuir-Hinshe1wood and Eley-Rideal mechanisms, and it is found that Langmuir-Hinshelwood mechanisms should be more important than Eley-Rideal processes for many surface reactions.
D.L. Freeman and J.D. Doll, “The Influence of Diffusion on Surface Reaction Kinetics,” J. Chem. Phys., 78, 6002-6009 (1983).