Hydrogen evolution at mercury from acid concentrated aqueous solutions of indifferent salts

The possible reasons of the hydrogen overvoltage decrease at high supporting electrolyte concentrations have been considered. It follows from a comparative study of the kinetic isotope effect and overvoltage shifts that the overvoltage decrease cannot be ascribed to the Ψ₁ effect caused by the specific anion adsorption. The overvoltage decrease is associated with the discharge activation energy. It is suggested that in a high-concentration solution the hydroxonium ion is actually located in a different medium, which corresponds to a lower reorganization energy.