Electrical double-layer interaction between oppositely charged dissimilar oxide surfaces with charge regulation and Stern–Grahame layers

The force of double-layer interaction between dissimilar flat oxide surfaces charged oppositely at infinite separation and with Stern–Grahame layers was calculated as a function of the surface separation under the conditions of charge regulation. The interaction force showed a monotonic attraction with respect to the surface separation, lying between constant surface potential and constant surface charge conditions. The variations of surface potentials and surface charge densities of respective double layers were also presented as functions of the surface separation. When the negative diffuse-layer potential at infinite separation changed its sign to positive as a result of specific adsorption of cations on the negatively changed surface, the double-layer interaction force showed a repulsive force barrier followed by an attraction at some particular separation. Oppositely charged dissimilar double-layer interaction force is always attractive (Fig. 1(1), Fig. 2(1)). When − ψ d 2 becomes positive due to specific adsorption of cations (Fig. 1(2)) the force shows a repulsive force barrier (Fig. 2(2)).