Tunneling through thin adsorbed films in-ion discharge at the limiting current—II: Computer calculations in W.K.B. approximation for metal/electrolyte-solution interface

Abstract

Computer calculations have been carried out in order to find the numerical correlation between the neutralisation distance, s, and the electrode potential, V, at the limiting current in the cases of Cu, Hg and Au. The equations at the limiting current for the interface metal/electrolyte have been considered in two approximations: the rectangular potential barrier and the parabolic one. In the case of the rectangular barrier the neutralisation distance increases at 2 V with 2Å even in the most unfavourable condition of the chosen s initial value (3Å). The relationship of s vs V does not vary appreciably when the barrier height, nature of the metal and the free electron level in solution have been changed. But considerable effect of all these parameters has been found in the case of the parabolic barrier, where the s distances are much larger. The most important parameter is the height of the free electron level in the bulk of the solution. The final conclusion of the present computer calculation is that the elementary act mechanism of the electrochemical reactions is different at the limiting current, when the electrode potential increases, as compared to the same mechanism below the limiting current. The difference consists mainly in the different distance where the ion can be neutralised.