Isotope separation factor and kinetic isotope effect of the hydrogen evolution reaction

In the framework of junified approach the experimentally observed dependences of kinetic isotopic effects (KIE) of the reaction of hydrogen electrolytic evolution on the value of potential on electrode were explained. It is shown that hydrogen isotope separation factor depends on KIE for two stages of the reaction, i.e. discharge on the electrode and electrochemical desorption, moreover, decrease in KIE with potential for the desorption stage overbalances its growth for the discharge stage. The reason for KIE decrease is non-activation character of the process, therefore, there is no dependence on potential of relative contribution of the product vibration-excited states