Asymmetric adsorption in an open electrolytic cell

Bousiadi, Sofia; Lelidis, I.

doi:10.1016/j.physleta.2017.10.050

Cited by 5 publications

(8 citation statements)

References 39 publications

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“…These observations and data support our simplifying assumption that no Faradaic reactions took place between the electrodes and the electrolyte. Theoretical studies have shown that different ion adsorption and desorption rates on electrodes can cause a potential difference of around the thermal voltage [67]. Hence, specific ion adsorption may have contributed to our measured SPD.…”

Section: A Seebeck Coefficient Literature Comparisonmentioning

confidence: 94%

On the time-dependent electrolyte Seebeck effect

Sehnem

Janssen

2021

The Journal of Chemical Physics

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Single-ion Soret coefficients αi characterize the tendency of ions in an electrolyte solution to move in a thermal gradient. When these coefficients differ between cations and anions, an electric field can be generated. For this so-called electrolyte Seebeck effect to occur, the different thermodiffusive fluxes need to be blocked by boundaries-electrodes, for example. Local charge neutrality is then broken in the Debye-length vicinity of the electrodes. Confusingly, many authors point to these regions as the source of the thermoelectric field yet ignore them in derivations of the time-dependent Seebeck coefficient S(t), giving a false impression that the electrolyte Seebeck effect is purely a bulk phenomenon. Without enforcing local electroneutrality, we derive S(t) generated by a binary electrolyte with arbitrary ionic valencies subject to a time-dependent thermal gradient. Next, we experimentally measure S(t) for five acids, bases, and salts near titanium electrodes. For the steady state we find S ≈ 2 mV K −1 for many electrolytes, roughly one order of magnitude larger than predictions based on literature αi. We fit our expression for S(t) to the experimental data, treating the αi as fit parameters, and also find larger-than-literature values, accordingly.

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Section: A Seebeck Coefficient Literature Comparisonmentioning

confidence: 94%

On the time-dependent electrolyte Seebeck effect

Sehnem

Janssen

2021

The Journal of Chemical Physics

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“…This result points to the direction that equation 2 is still not a complete model for the reality of the thermoelectric experiment. Some of the effects neglected in current descriptions are electrodes polarization from differential ionic adsorption [27,28] and specific interactions between electrodes and electrolytes [29]. From the theoretical point of view, the temperature dependence of single-ion Soret and mass diffusion coefficients are necessary to be considered in Janssen and Bier's theory [23] in order to obtain a more complete theory.…”

Section: Resultsmentioning

confidence: 99%

Dynamic response of a thermoelectric cell induced by ion thermodiffusion

Sehnem¹,

Neto²

2019

Preprint

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Aqueous electrolyte solutions under the influence of a temperature gradient can generate thermoelectric fields, which arise from different responses of the positive and negative charges. This is related to the thermodiffusion effect which is quantified by the ionic heat of transport and the thermal diffusion coefficient. When a solution is confined between two metallic electrodes with different temperatures, it is expected to measure the electrostatic potential difference due to the thermoelectric field. We performed experiments in aqueous electrolyte solutions, and our results show that a thermoelectric field appears instantly in the solution as the temperature difference between the electrodes stabilizes. This field arises from the trend to separate both ionic charges in the temperature gradient. The experimental results also show that a slow change in the potential difference is observed, which is related to thermodiffusion in the entire cell. These results are important to understand how the thermoelectric response can be optimized, given the broad interest in the literature to generate thermoelectric energy from thermoelectric cells.

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“…In this case, if in thermodynamical equilibrium the liquid is locally and globally neutral, in the presence of the adsorption phenomenon, the liquid is locally charged close to the surface, and an electric field is present [2]. In this situation, the electric potential of the electrode differs from that in the bulk [3]. Our goal is to investigate the temporal evolution of the surface electric field in a cell in the presence of ionic adsorption.…”

Section: Introductionmentioning

confidence: 99%

“…Our goal is to investigate the temporal evolution of the surface electric field in a cell in the presence of ionic adsorption. The analysis is performed in the framework of the Poisson-Nernst-Planck model, based on the conservation of particles and on the equation of Poisson for the actual electric potential across the cell [3][4][5]. The adsorption is described using a kinetic equation of Langmuir's type, involving the adsorption coefficient and the desorption time [6].…”

Section: Introductionmentioning

confidence: 99%

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Analytical description of the ionic relaxation in the presence of surface adsorption

Barbero,

Aliyev,

Scarfone

2024

J. Phys. A: Math. Theor.

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The temporal evolution of the surface electric field in a cell in the presence of ionic adsorption is investigated. The analysis is performed in the framework of the Poisson-Nernst-Planck model, based on the conservation of particles and the equation of Poisson for the actual electric potential across the cell, assuming that only the ions of a given sign are mobile. The adsorption is described using a kinetic equation of Langmuir's type. The simple case of small adsorption is considered, in which the saturation effect can be neglected, and the fundamental equations of the model can be linearized. In this framework, the effective relaxation time describing the dynamics of the system is evaluated, as well as the profiles of the ions and the electric field. The case in which the sample is a half-space is first considered. A more realistic situation where the sample is a slab of thickness $d$, limited by two identical or different electrodes, is analyzed too. The difference in electric potential due to the adsorption phenomenon between the electrodes is determined. Our analysis shows that its time dependence, when the electrodes have different adsorption properties, is not monotonic.

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Asymmetric adsorption in an open electrolytic cell

Cited by 5 publications

References 39 publications

On the time-dependent electrolyte Seebeck effect

On the time-dependent electrolyte Seebeck effect

Dynamic response of a thermoelectric cell induced by ion thermodiffusion

Analytical description of the ionic relaxation in the presence of surface adsorption

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