Proton transfer in electrode reactions. Experimental test of two theoretical models

Abstract

All the experimental data on the kinetics of the cathodic discharge of proton donors allowing a choice to be made between two models of an elementary act of proton transfer, the bond-stretching model and the medium-reorganization model, are considered. The specific features of electrochemical processes allowing investigation of the influence of certain factors which cannot be examined by the methods based on the kinetics of homogeneous chemical reactions are discussed. The data concerning barrierless discharge, the influence of the nature of the electrode metal on the preexponential factor and the kinetic isotopic effect, the influence of potential on the isotopic effect during the discharge of H₃O⁺ and H₂O, the influence of the nature of the solvent and bond breaking on the activation energy, etc., are analysed. All the experimentally observed relationships are at variance with the conclusions of the bond-stretching model and in full agreement with the predictions of the medium-reorganization model.