Asymmetric adsorption in an open electrolytic cell

TL;DR

This paper models how ion adsorption-desorption affects potential difference in an open electrolytic cell using Poisson-Nernst-Planck and Langmuir theories, providing analytical and numerical insights into charge distribution and relaxation times.

Contribution

It introduces a combined theoretical framework for analyzing ion adsorption effects on potential difference in electrolytic cells, including analytical formulas and numerical relaxation time calculations.

Findings

Selective ion adsorption induces potential difference.

Analytical expressions for charge distribution derived.

Numerical analysis of relaxation times conducted.

Abstract

We investigate the effect of adsorption-desorption phenomenon of ions in an asymmetric electrolytic cell at open circuit conditions. Our approach is based on the Poisson-Nernst-Planck theory for electrolytes and the kinetic model of Langmuir for the description of adsorption-desorption phenomena on the electrodes. When the electrodes are immersed into the solution, selective ion adsorption takes place. It is shown, that the selective ion adsorption is responsible for generating an electrical potential difference between the electrodes of the cell. The analytical expressions for the potential difference and for the charge distribution are calculated. Finally, the time evolution of the system is investigated and the relaxation times of the problem are deduced numerically.