Contribution of the electrode-electrolyte interface to the impedance of an electrolytic cell

Abstract

We analyze the experimental data relevant to samples of solutions of water and KCl, in the shape of slabs of different thicknesses, with electrodes in gold. The experimental data show an increase in the real part of the electrical impedance of the samples in the low frequency region ͑f ϳ 5 Hz͒. We compare the theoretical predictions of the models proposed to interpret the anomalous behavior of the resistance of the sample in the dc limit with the experimental data. We show that the theoretical predictions of the models based on the adsorption of ions at the interface and on the Ohmic character of the electrodes are in good agreement with experimental data. The model based on the constant phase element is also considered. However, its agreement with the considered experimental data is very good for what concerns the real part, whereas it is poor for the imaginary part of the electrical impedance. The equivalence between the models based on the adsorption on the electrodes and on the Ohmic character of the electrodes is analyzed. From the good agreement between the two descriptions, a mechanism for the conduction across the electrodes is proposed, according to which the exchange of charge on the electrode takes place in two steps: one related to the adsorption of the ions, and the other connected with their neutralization from the external charges.

Time-Constant-Domain Spectroscopy: An Impedance-Based Method for Sensing Biological Cells in Suspension

“…3(a), one can see two main processes involved in EIS measurements. For all the samples, a straight-line-kind trend appears at low frequencies, which is presumably due to the interaction of the WE with the suspensions [40]. At high frequencies, for the seven suspensions, one can see a semicircle suggesting changes as a function of the concentration due to the interaction among the particles and the PBS 1X, as extensively described in the literature.…”

Dielectric Dispersion of Water in the Frequency Range from 10 mHz to 30 MHz

“…Another possibility to fit the data is by means of the constant phase element. , According to this approach, from the electrical point of view the interface between the bulk and the electrodes is described by a surface impedance Z nt = A ( i ω ) − ν where A and ν are two phenomenological parameters characteristics for the electrodes and the solution (in our case water). For a discussion on Z int see refs and .…”

Electric Impedance of a Sample of Dielectric Liquid Containing Two Groups of Ions Limited by Ohmic Electrodes: A Study with Pure Water

“…The hypothesis of a generalization of the model to take into account the presence of several groups of ions has also been discussed . Other generalizations have been proposed to take into account the ionic adsorption on the electrodes. − Also the possibility of anomalous diffusion has been explored. − All the quoted generalizations have been proposed to justify anomalous behavior of the real and imaginary parts of the electrical impedance in the low frequency region, usually discussed in terms of the constant phase element, whose physical meaning is unclear …”