Concentration dependence of overpotential of hydrogen evolution on copper from acid solutions

The results are presented on the overpotential of hydrogen evolution at copper electrode from perchloric acid solutions in the concentration range from 0.14 to 9.31 M, and also on the electrical conductivity of these solutions. For the solutions studied, it is found that the hydrogen ion discharge on copper proceeds with the slow stage of electron transfer. It is shown that the concentration dependence of overpotential agrees quantitatively with equations of electrode kinetics only to the concentrations not exceeding the boundary of complete hydration. The deviations from theory, which are observed in concentrated solutions, are explained by a change in the composition of discharging species