The influence of surface energetic heterogeneity on electrofluidic gating of a metal oxide surfaces

Abstract

We developed a theoretical model which describes the influence of the applied potential to the wall of an oxide nanochannel on the diffuse layer potential in the solution filling the nanopore. It was assumed that the surface of oxide is energetically heterogeneous and electrolyte ions from the solution can adsorb on channel walls. We performed calculations for two oxides: SiO 2 and Al 2 O 3 . It was found that energetically heterogeneous oxide surfaces strongly suppress gating potential. Moreover, taking into account ion adsorption considerably increased the electrokinetic potential and reduced the influence of applied potential on the electric double layer in the solution. The density of surface sites is the key parameter in the modeling of oxide nanochannels. Low density of surface hydroxyl groups significantly increases susceptibility on electrofluidic gating.