Ionic Conductivity of Nanopores with Electrically Conductive Surface: Comparison Between 1D and 2D Models

Abstract

Nanoporous membranes with high ionic conductivity are advantageous in such electrochemical processes as (reverse) electrodialysis, capacitive deionization, and hydrogen energy conversion. In membranes with electrically conductive surface, the conductivity can be regulated by varying the surface potential. This work is devoted to the theoretical study of switchable ionic conductivity. The transport of ions is described by the 2D space charge model and 1D uniform potential model taking into account the Stern layer. The conductivity decreases with lowering the Stern layer permittivity due to enhanced screening of electronic surface charge. The growth of surface potential leads to the conductivity enhancement due to accumulation of more counter‐ions inside the nanopore. For nanopores with constant surface charge density, the ionic conductivity follows the bulk electrolyte conductivity at high ion concentrations, and becomes independent of concentration when the latter is low. In contrast, the nanopores with constant surface potential demonstrate a linear decrease of conductivity with lowering the logarithm of ion concentration. The deviation between 1D and 2D models becomes noticeable at higher values of Stern layer permittivity, pore radius, electrolyte concentration, and surface potential. The proposed models are verified by comparison with experimental data on pure water conductivity in charged porous matrix.

Ultra-Low Intensity Light-Driven Ionic Conductivity through a Plasmonic Nanopore

“…The theoretical description of ion transport through a nanopore (considered a nanochannel) was based on the uniform potential model, which was derived from the Navier–Stokes, Nernst–Planck, and Poisson equations. , We consider a cylindrical nanochannel of radius R P and length L P , which separates two reservoirs L (left) and R (right) with an aqueous solution of the same monovalent and symmetric (1:1) electrolyte of concentration C 0 . The motion of the ions is induced by the electric field, which is imposed by specifying different potentials Φ L and Φ R in the reservoirs.…”

Modelling the Performance of Electrically Conductive Nanofiltration Membranes

“…The interaction between an electronic charge and a pH-dependent chemical charge and their impact on the membrane potential were theoretically analyzed in [ 44 ]. 1D and 2D models describing the transport of ions under concentration and electrical potential gradients in conductive membranes were proposed and validated against experimental data in [ 45 , 46 ].…”