Electrochemical impedance of electrodiffusion in charged medium under $dc$ bias

Abstract

An immobile charged species provides a charged medium for transport of charge carriers that is exploited in many applications, such as permselective membranes, doped semiconductors, biological ion channels, as well as porous media and microchannels with surface charges. In this paper, we theoretically study the electrochemical impedance of electrodiffusion in a charged medium by employing the Nernst-Planck equation and the electroneutrality condition with a background charge density. The impedance response is obtained under different dc bias conditions, extending above the diffusion-limiting bias. We find a transition in the impedance behavior around the diffusion-limiting bias, and present an analytical approximation for a weakly charged medium under an overlimiting bias.

arXiv comment33 pages, 10 figures. Supplemental materials (MATLAB scripts) can be accessed at https://github.com/JuhyunSong/Impedance_2019.git

References in corpus (11)

• Diffuse-Charge Dynamics in Electrochemical Systems
• Sinc approximation of algebraically decaying functions
• Overlimiting current in a microchannel
• Analysis of electrolyte transport through charged nanopores
• Desalination shocks in microstructures
• Experimental Verification of Overlimiting Current by Surface Conduction and Electro-osmotic Flow in Microchannels
• Electroneutrality Breakdown and Specific Ion Effects in Nanoconfined Aqueous Electrolytes Observed by NMR
• Theory of linear sweep voltammetry with diffuse charge: unsupported electrolytes, thin films, and leaky membranes
• Concentration polarization, surface currents, and bulk advection in a microchannel
• Theoretical interpretation of Warburg's impedance in electrolytic cells
• Theory of voltammetry in charged porous media