Department of Chemistry, Ohio State University, Columbus, Ohio 43210, USA.
J Chem Phys. 2011 Jan 14;134(2):024705. doi: 10.1063/1.3510536.
To explain why dynamical properties of an aqueous electrolyte near a charged surface seem to be governed by a surface charge less than the actual one, the canonical Stern model supposes an interfacial layer of ions and immobile fluid. However, large ion mobilities within the Stern layer are needed to reconcile the Stern model with surface conduction measurements. Modeling the aqueous electrolyte-amorphous silica interface at typical charge densities, a prototypical double layer system, the flow velocity does not vanish until right at the surface. The Stern model is a good effective model away from the surface, but cannot be taken literally near the surface. Indeed, simulations show no ion mobility where water is immobile, nor is such mobility necessary since the surface conductivity in the simulations is comparable to experimental values.
为了解释为什么带电荷表面附近的水溶液电解质的动力学性质似乎受小于实际表面电荷的控制，典型的 Stern 模型假设界面层有离子和不可动的流体。然而，需要 Stern 层内的大离子迁移率才能使 Stern 模型与表面传导测量结果相一致。在典型的电荷密度下对水溶液-无定形二氧化硅界面建模，作为典型的双层体系，直到表面附近，流速才不会为零。Stern 模型在远离表面时是一个很好的有效模型，但在靠近表面时不能按字面意思理解。实际上，模拟结果表明，在水不可动的地方没有离子迁移率，也不需要这种迁移率，因为模拟中的表面电导率与实验值相当。
