Nonlinearly induced electro-osmotic flow reversal in charged nanotube: Counter-ions mobility in Stern layer

Abstract

In the electric double layer (EDL) theory, the Stern layer formation under external electric field has not been clearly understood so far. In this work, the effect of electric field intensity (E) on reverse electro-osmotic flow (EOF) of an aqueous KCl solution confined in a charged nanotube was analyzed based on the MD simulations. The counter-ions in Stern layer captured by the surface charges were generally assumed to be immobile ones, however, our results reveal that the partial of them can escape under the action of external electric field. The charge inversion degree is found negatively proportional to the E. The reverse EOF velocity shows a cubic function of the E, it increases then decreases as the E increases, in which the electric driving force and the charge inversion degree are the dominant factors, respectively. Our findings can contribute to the fundamental understanding of EOF behavior in nano-fluidic channel.