Theory of electrified interfaces

Abstract

A new theory for the electrified interfaces, using the mean spherical and exponential approximations as the starting point, is proposed. This theory is based on a general result of Blum and Stell. It treats the exclusion volume effects exactly and consistently, but the long-range electrostatic forces are treated in an approximation; for the mean spherical case it is equivalent to the linearized Debye-Huckel theory. General expressions for the differential capacitance are given; in the limiting cases of zero potential, equal size, and low concentration they agree with the classic result of the linear Guoy-Chapman theory. The exponential approximation result with no image forces has a parabolic dependence in the applied potential for low potentials, but, unlike the classical result, it remains finite as the applied potential grows.