Electrode potential and selective ionic adsorption

A simple description of the electrode potential based on the selective ionic adsorption is proposed. It is shown that if the adsorption–desorption coefficients entering in the Langmuir kinetic equation for the adsorption at the limiting surfaces are not identical, a difference of potential between the electrode and the bulk of the solution exists. In the case where the thickness of the sample is large with respect to the length of Debye, this difference of potential depends only on the adsorption–desorption coefficients and on the length of Debye of the ionic solution.