Theory of the electric double layer using a modified poisson–boltzman equation

Abstract

A modified Poisson–Boltzmann equation in diffuse double-layer theory which includes estimates for the fluctuation and exclusion volume terms is solved numerically for a 1 : 1 restricted-model electrolyte. Two estimates of the exclusion-volume term are considered at three electrolyte concentrations with varying surface charge when image terms are neglected. Details are given of the numerical calculation and double-layer properties such as the mean electrostatic potential, the ion–wall distribution functions and the differential capacitance are presented. Comparisons are made with the Gouy–Chapman–Stern theory and with some preliminary hypernetted chain (HNC) calculations.