A less-explored surface property: The electrical double layer and its molecular interrogation capability

Introduction. Electrical double layer (EDL) forms spontaneously through thermodynamic interaction between electrons and ions at a solid-liquid interface (SLI). A close examination of the literature reveals that in the classical EDL theories^[1] the ionic species were assumed to follow Boltzmann distributions with no electron transfer across the SLI. In our previous works^[2-3], we reexamined the problem by considering the ionic and molecular interactions within the compact and diffuse layers along with an electrochemical process under the governing principles of the Poisson, Nernst-Plank and Butler-Volmer equations. We, on the one hand, confirmed that the ionic concentration did follow a Boltzmann distribution only when the net current across the SLI is zero, and on the other hand, expanded the dealing of ions and molecules inside the EDL without assuming zero electron transfer. One importance implication of this is that it allows us to use either a charging or Faraday current to perturb the thermodynamic equilibrium state of the EDL. In this study we push further to perturb the EDL for molecular interrogation at a surface inside a nanopore.