Non-local effects in the kinetics of heterogeneous charge transfer reactions

The effect of the solvent spatial dispersion and the field penetration into a metal on the kinetic parameters of the heterogeneous charge-transfer reactions is studied. The calculations are based on the exactly solvable ‘sharp boundary model’ of the interface, the Born sphere model of an ion and the Lorentzian form for the dielectric function of the solvent. It is shown that the reorganization Gibbs energy and the activation Gibbs energy decrease with decrease of the electrode–reactant separation in accordance with Marcus theory (in which the non-local effects are neglected) and in contrast with the results of Dzhavakhidze, Kornyshev and Krishtalik [J. Electroanal. Chem. 228 (1987) 329]. The reorganization Gibbs energy is found to be smaller than that given by the Marcus formula. The effect of the overscreening phenomenon on the results obtained is discussed.