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In Seok Kang - One of the best experts on this subject based on the ideXlab platform.
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Specific ion effects on Electrocapillarity in aqueous electrolytes confined within nanochannels.
Physical Review E, 2019Co-Authors: Saksham Gupta, In Seok KangAbstract:A nanoslit is a long, extremely narrow (nanometers apart) opening between two parallel plates. An overlapped electric double layer is formed when an electrolyte is present inside the slit and there exist distributions of the osmotic pressure and the Maxwell stress across the nanoslit, which lead to the Electrocapillarity effect. This feature can be incorporated with the specific ion effects by considering the nonelectrostatic interactions between ions and confining walls, as they significantly influence the potential, electric field, and ion distributions across the nanoslit. In the present work, the electromechanical approach is integrated with the concept of specific ion effects to analyze the behavior of an electrolyte confined in a one-dimensional nanochannel. For a nanochannel, the average outward normal stress exerted on the cross section of a channel ($\overline{{P}_{zz}}$) can be regarded as a measure of Electrocapillarity and it is the driving force of the flow. This Electrocapillarity measure is analyzed by using the solution of the modified Poisson-Boltzmann equation as a function of the bulk concentration of the electrolyte, the boundary potential, and most importantly, the ion-specific interfacial interactions. The significance of the present work can be manifested by the increasing usage of extremely narrow channels in nanoscaled systems, which will require proper consideration of specific ion effects in determining the behavior of the confined electrolyte.
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Specific ion effects on Electrocapillarity in aqueous electrolytes confined within nanochannels.
Physical review. E, 2019Co-Authors: Saksham Gupta, In Seok KangAbstract:A nanoslit is a long, extremely narrow (nanometers apart) opening between two parallel plates. An overlapped electric double layer is formed when an electrolyte is present inside the slit and there exist distributions of the osmotic pressure and the Maxwell stress across the nanoslit, which lead to the Electrocapillarity effect. This feature can be incorporated with the specific ion effects by considering the nonelectrostatic interactions between ions and confining walls, as they significantly influence the potential, electric field, and ion distributions across the nanoslit. In the present work, the electromechanical approach is integrated with the concept of specific ion effects to analyze the behavior of an electrolyte confined in a one-dimensional nanochannel. For a nanochannel, the average outward normal stress exerted on the cross section of a channel (P_{zz}[over ¯]) can be regarded as a measure of Electrocapillarity and it is the driving force of the flow. This Electrocapillarity measure is analyzed by using the solution of the modified Poisson-Boltzmann equation as a function of the bulk concentration of the electrolyte, the boundary potential, and most importantly, the ion-specific interfacial interactions. The significance of the present work can be manifested by the increasing usage of extremely narrow channels in nanoscaled systems, which will require proper consideration of specific ion effects in determining the behavior of the confined electrolyte.
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Geometric effects on Electrocapillarity in nanochannels with an overlapped electric double layer.
Physical review. E, 2016Co-Authors: Jung A Lee, In Seok KangAbstract:Unsteady filling of electrolyte solution inside a nanochannel by the Electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. For a nanochannel, the average outward normal stress exerted on the cross section of a channel (P[over ¯]_{zz}^{}) can be regarded as a measure of Electrocapillarity and it is the driving force of the flow. This Electrocapillarity measure is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of κh→0 and κh→∞, it can be shown theoretically that the Electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular N-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanochannel. It is found that the average filling velocity decreases as N increases in the case of regular N-polygons with the same hydraulic radius. This is because the regular N-polygons of the same hydraulic radius share the same inscribing circle.
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Geometric effects on Electrocapillarity in nanochannels with an overlapped electric double layer.
Physical Review E, 2016Co-Authors: Jung A Lee, In Seok KangAbstract:Unsteady filling of electrolyte solution inside a nanochannel by the Electrocapillarity effect is studied. The filling rate is predicted as a function of the bulk concentration of the electrolyte, the surface potential (or surface charge density), and the cross sectional shape of the channel. For a nanochannel, the average outward normal stress exerted on the cross section of a channel $({\overline{P}}_{zz}^{})$ can be regarded as a measure of Electrocapillarity and it is the driving force of the flow. This Electrocapillarity measure is first analyzed by using the solution of the Poisson-Boltzmann equation. From the analysis, it is found that the results for many different cross sectional shapes can be unified with good accuracy if the hydraulic radius is adopted as the characteristic length scale of the problem. Especially in the case of constant surface potential, for both limits of $\ensuremath{\kappa}h\ensuremath{\rightarrow}0$ and $\ensuremath{\kappa}h\ensuremath{\rightarrow}\ensuremath{\infty}$, it can be shown theoretically that the Electrocapillarity is independent of the cross sectional shape if the hydraulic radius is the same. In order to analyze the geometric effects more systematically, we consider the regular $N$-polygons with the same hydraulic radius and the rectangles of different aspect ratios. Washburn's approach is then adopted to predict the filling rate of electrolyte solution inside a nanochannel. It is found that the average filling velocity decreases as $N$ increases in the case of regular $N$-polygons with the same hydraulic radius. This is because the regular $N$-polygons of the same hydraulic radius share the same inscribing circle.
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Ion size effects on the osmotic pressure and Electrocapillarity in a nanoslit: Symmetric and asymmetric ion sizes.
Physical review. E, 2016Co-Authors: Rajni, In Seok KangAbstract:We analyze the effect of asymmetric finite ion size in nanoconfinement in the view of osmotic pressure and Electrocapillarity. When the confinement width becomes comparable with the Debye length, the overlapped electric double layer is significantly deformed by the steric effects. We derive the osmotic pressure from the modified Poisson-Boltzmann equation in a nanoslit to examine the deviation from the ideal osmotic pressure and the repulsive force on the wall considering the asymmetry of ion sizes. Then the Electrocapillarity due to the steric effect is investigated under constant potential condition with the flat interface assumption. Later, the deformation by the Electrocapillarity is also considered in the first order approximation.
Laurent Gaillon - One of the best experts on this subject based on the ideXlab platform.
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interfacial properties of mercury ethylammonium nitrate ionic liquid water system Electrocapillarity surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid+water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/ EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance data indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid + water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
Emmanuel M. Gutman - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic aspects of capillarity and Electrocapillarity of solid interfaces
Journal of Solid State Electrochemistry, 2016Co-Authors: Emmanuel M. GutmanAbstract:In the previous paper (Gutman, JOSSEC 18:3217–3237, 2014 ), we have shown that the main problem in capillarity and Electrocapillarity of solid surfaces is the lack of clarity in determining the surface stress and basic equations. Now, we continue the survey of efforts to solve this problem and show origins of erroneous results, accenting some important items: comparative analysis of Gibbs and Guggenheim approaches in surface thermodynamics (a geometrical dividing surface and finite-thickness surface layer, respectively), transformation of fundamental equations on per-unit-area basis to obtain Gibbs adsorption equation for finite-thickness surface layer, different attempts to derive the thermodynamic definition of “surface stress” in frames of Gibbs’ theory (including Shuttleworth’s approach), atomistic calculations of surface stress, surface stress in rational continuum mechanics, “modifications” of Gibbs–Duhem relations made for solid interface, and Maxwell relations in capillarity and Electrocapillarity of solid interface. It is shown that the erroneous Shuttleworth’s approach is present in an explicit or implicit form in all efforts to introduce the surface stress in frames of Gibbsian theory (although Gibbs did not introduce surface stress). Therefore, “modernizations” or “generalizations” of the Gibbs–Duhem relation, the Gibbs adsorption equation, and the Lippmann equation to adopt them for a solid surface are unnatural and not necessary. Therefore, we recommend withdrawing the Shuttleworth equation and its consequences from circulation, including the IUPAC Recommendations.
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Theoretical problems in solid Electrocapillarity
Journal of Solid State Electrochemistry, 2014Co-Authors: Emmanuel M. GutmanAbstract:The main problem in Electrocapillarity of solid electrodes is the lack of clarity in determining the surface stress and basic equations. Within the framework of the Gibbs concept of geometrical dividing surface, the “surface stress” cannot be defined because methods of continuum mechanics can be applied to a physical surface layer (of finite thickness), but not to a mathematical surface. Gibbs never used the concept of surface stress, introducing only “surface tension” for a liquid electrode and “closely related quantity” for a solid electrode. Revisiting the derivation of the Gibbs adsorption equation, we prove its applicability to solid surfaces without the limiting requirement of constant state of strain, which was undeservedly interpreted by Eriksson as a shortcoming of the Gibbs theory caused to look for other approaches to surface stress problem. A critical analysis shows that the attempts (Shuttleworth, Eriksson, Couchman, Gokhstein, Weissmüller, etc.) to create a thermodynamic definition of the surface stress (as well as the formulation of fundamental thermodynamic equations and Maxwell relations operating with surface stresses) contain mathematical defects. It is shown that confusing interpretations of some Gibbs’ concepts encountered in the literature have led to “modifications” of the Lippmann equation based on the critical error in the Gibbs–Duhem relation due to the occurrence of an extensive variable, which is inadmissible. The famous Lippmann equation should not be modified, and it remains a unique electrocapillary relation applicable to liquid and solid electrodes.
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Comment on “On the ‘simple check’ of Electrocapillarity” by AY Gokhshtein
Journal of Solid State Electrochemistry, 2014Co-Authors: Emmanuel M. GutmanAbstract:It is shown that the so-called “equation of solid-state Electrocapillarity” derived by Gokhshtein from the simplest thermodynamic model, earlier used by Lippmann, is an incorrect modification that is returned to the classic Lippmann equation if to take into account the usual definition of differential capacity of the electrical double layer. Consequently, Gokhshtein’s experiments can actually confirm only the validity of the Lippmann equation (with deviations caused by physicochemical processes in the double layer, which could not be taken into account in the thermodynamic equations). The thermodynamic model is insufficient for the interpretation s of these experimental results, whose understanding requires physical models of the different phenomena occurring at the electrode surface.
Malika Ammam - One of the best experts on this subject based on the ideXlab platform.
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interfacial properties of mercury ethylammonium nitrate ionic liquid water system Electrocapillarity surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid+water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/ EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance data indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid + water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
Dung Di Caprio - One of the best experts on this subject based on the ideXlab platform.
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interfacial properties of mercury ethylammonium nitrate ionic liquid water system Electrocapillarity surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid+water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/ EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance data indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.
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Interfacial properties of mercury/ethylammonium nitrate ionic liquid + water system: Electrocapillarity, surface charge and differential capacitance
Electrochimica Acta, 2012Co-Authors: Malika Ammam, Dung Di Caprio, Laurent GaillonAbstract:In this account, surface tensions of mercury/ethylammonium nitrate (EAN) aqueous solutions at different compositions as a function of the potential have been measured. Using the first and the second derivative of surface tension curves, surface charge and differential capacitance have been obtained. Assumptions based on simple hypotheses and comparison of the EAN behavior with respect to ammonium nitrate (AN) provided information about the ionic structure at the interface mercury/EAN solutions. The results from the Electrocapillarity maximum data suggest excess adsorption of the nitrate anions at low EAN concentrations and excess adsorption of the ethylammonium cations at higher concentrations. The results from the differential capacitance indicate that the ethyl group of the EAN cation would preferably be oriented towards the metal mercury.