Polarization of disk electrodes in high-conductivity electrolyte solutions

Kenneth K Yamamoto; Anil Koklu; Ali Beskok; Vladimir S Ajaev

doi:10.1063/5.0179083

Polarization of disk electrodes in high-conductivity electrolyte solutions

J Chem Phys. 2024 Feb 7;160(5):054702. doi: 10.1063/5.0179083.

Authors

Kenneth K Yamamoto¹, Anil Koklu², Ali Beskok³, Vladimir S Ajaev^{1

3}

Affiliations

¹ Department of Mathematics, Southern Methodist University, Dallas, Texas 75275, USA.
² Biological and Environmental Sciences and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
³ Department of Mechanical Engineering, Southern Methodist University, Dallas, Texas 75275, USA.

PMID: 38299629
DOI: 10.1063/5.0179083

Abstract

We investigate the polarization of disk electrodes immersed in an electrolyte solution and subjected to a small external AC voltage over a wide range of frequencies. A mathematical model is developed based on the Debye-Falkenhagen approximation to the coupled Poisson-Nernst-Planck equations. Analytical techniques are used for predicting the spatial distribution of the electric potential and the complex impedance of the system. Scales for impedance and frequency are identified, which lead to a self-similar behavior for a range of frequencies. Experiments are conducted with gold electrodes of sizes in the range 100-350 μm immersed in a high-conductivity KCl solution over five orders of magnitude in frequency. A collapse of data on impedance magnitude and phase angle onto universal curves is observed with scalings motivated by the mathematical model. A direct comparison with the approximate analytical formula for impedance is made without any fitting parameters, and a good agreement is found for the range of frequencies where the analytical model is valid.