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Xiao T, Song X. A Gaussian field approach to the solvation of spherical ions in electrolyte solutions. J Chem Phys 2024; 160:034102. [PMID: 38226821 DOI: 10.1063/5.0187141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 12/25/2023] [Indexed: 01/17/2024] Open
Abstract
In this work, the electrostatic response of an electrolyte solution to a spherical ion is studied with a Gaussian field theory. In order to capture the ionic correlation effect in concentrated solutions, the bulk dielectric response function is described by a two-Yukawa response function. The modified response function of the solution is solved analytically in the spherical geometry, from which the induced charge density and the electrostatic energy are also derived analytically. Comparisons with results for small ions in electrolyte solutions from the hyper-netted chain theory demonstrate the validity of the Gaussian field theory.
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Affiliation(s)
- Tiejun Xiao
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University, Guiyang People's Republic of China
| | - Xueyu Song
- Department of Chemistry and Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
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2
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Xiao T, Song X. A Gaussian field approach to the planar electric double layer structures in electrolyte solutions. J Chem Phys 2023; 158:2887562. [PMID: 37125713 DOI: 10.1063/5.0138568] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 04/17/2023] [Indexed: 05/02/2023] Open
Abstract
In this work, the planar, electric, double-layer structures of non-polarizable electrodes in electrolyte solutions are studied with Gaussian field theory. A response function with two Yukawa functions is used to capture the electrostatic response of the electrolyte solution, from which the modified response function in the planar symmetry is derived analytically. The modified response function is further used to evaluate the induced charge density and the electrostatic potential near an electrode. The Gaussian field theory, combined with a two-Yukawa response function, can reproduce the oscillatory decay behavior of the electric potentials in concentrated electrolyte solutions. When the exact sum rules for the bulk electrolyte solutions and the electric double layers are used as constraints to determine the parameters of the response function, the Gaussian field theory could at least partly capture the nonlinear response effect of the surface charge density. Comparison with results for a planar electrode with fixed surface charge densities from molecular simulations demonstrates the validity of Gaussian field theory.
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Affiliation(s)
- Tiejun Xiao
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Synergetic Innovation Center of Scientific Big Data for Advanced Manufacturing Technology, Guizhou Education University, Guiyang 550018, People's Republic of China
| | - Xueyu Song
- Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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3
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Lamperski S, Bhuiyan LB. Entropy of electrolytes with off-centre charge cations. Monte Carlo studies. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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4
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Zhou S, Zhang LT. Analytical Solution of Modified Poisson–Boltzmann Equation and Application to Cylindrical Nanopore Supercapacitor Energy Storage. COLLOID JOURNAL 2022. [DOI: 10.1134/s1061933x22020107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Lamperski S, Bhuiyan LB. Entropy characteristics in an electric double layer with off-centre charge ions. A statistical thermodynamics approach. Mol Phys 2022. [DOI: 10.1080/00268976.2022.2045374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Stanisław Lamperski
- Department of Physical Chemistry, Adam Mickiewicz University in Poznań, Poznań, Poland
| | - Lutful Bari Bhuiyan
- Laboratory of Theoretical Physics, Department of Physics, University of Puerto Rico, San Juan, PR, USA
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6
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Islam MS, Lamperski S, Islam MM, Henderson D, Bhuiyan LB. Temperature dependence of differential capacitance in the electric double layer.Symmetric valency 1:1 electrolytes. J Chem Phys 2020; 152:204702. [PMID: 32486666 DOI: 10.1063/5.0005966] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The differential capacitance of an electric double layer formed by an aqueous solution of KNO3 on a glassy carbon electrode is measured by impedance analysis at constant frequency. Results are obtained at electrolyte concentrations of 0.1 mol/dm3, 0.5 mol/dm3, and 1.0 mol/dm3, and at a series of temperatures, viz., 288 K, 298 K, 308 K, 318 K, and 328 K. The differential capacitance envelopes reveal a rich, complex pattern of maxima, minima, and local minima, whose magnitude and position change with a change in solution concentration. At the two lower concentrations, the temperature dependence of the capacitance, for example, at zero electrode potential, shows an alternating positive-negative behavior, while at the highest concentration of 1.0 mol/dm3, the slope of the differential capacitance-electrode potential curve is always positive. The experimental results are supplemented by a numerical grand canonical Monte Carlo simulation study of a restricted primitive model double layer but with an off-center cationic charge achieved by displacing the charge center from the ion sphere center toward its surface. The simulations, performed at the electrolyte concentration of 1.0 mol/dm3 and constant cation charge center displacement, and at varying electrode potentials and temperatures, show, in general, a negative temperature dependence of the differential capacitance. However, this temperature dependence can also be positive for a negative electrode charge and for a sufficiently large gradient of the cation charge center displacement with temperature. This feature is seen to be associated with an increase in the entropy of formation of the double layer.
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Affiliation(s)
- Md Siful Islam
- Department of Chemistry, University of Dhaka, Dhaka 1000, Bangladesh
| | - Stanisław Lamperski
- Department of Physical Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland
| | - Md Mominul Islam
- Department of Chemistry, University of Dhaka, Dhaka 1000, Bangladesh
| | - Douglas Henderson
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602-5700, USA
| | - Lutful Bari Bhuiyan
- Laboratory of Theoretical Physics, Department of Physics, University of Puerto Rico, 17 University Avenue, Suite 1701, San Juan, Puerto Rico 00925-2537, USA
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7
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Hajar YM, Treps L, Michel C, Baranova EA, Steinmann SN. Theoretical insight into the origin of the electrochemical promotion of ethylene oxidation on ruthenium oxide. Catal Sci Technol 2019. [DOI: 10.1039/c9cy01421g] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In EPOC the adsorption energies of the reactants and products are modified by applying an electrochemical potential to the catalyst. DFT computations unveil that the C–C and O–O bond dissociation are accelerated under positive and negative potential, respectively.
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Affiliation(s)
- Yasmine M. Hajar
- Department of Chemical and Biological Engineering
- Centre for Catalysis Research and Innovation (CCRI)
- University of Ottawa
- Ottawa
- Canada
| | - Laureline Treps
- Univ. Lyon
- ENS de Lyon
- CNRS
- Université Lyon 1
- Laboratoire de Chimie UMR 5182
| | - Carine Michel
- Univ. Lyon
- ENS de Lyon
- CNRS
- Université Lyon 1
- Laboratoire de Chimie UMR 5182
| | - Elena A. Baranova
- Department of Chemical and Biological Engineering
- Centre for Catalysis Research and Innovation (CCRI)
- University of Ottawa
- Ottawa
- Canada
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8
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Parizi KB, Xu X, Pal A, Hu X, Wong HSP. ISFET pH Sensitivity: Counter-Ions Play a Key Role. Sci Rep 2017; 7:41305. [PMID: 28150700 PMCID: PMC5288728 DOI: 10.1038/srep41305] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 12/19/2016] [Indexed: 11/23/2022] Open
Abstract
The Field Effect sensors are broadly used for detecting various target analytes in chemical and biological solutions. We report the conditions under which the pH sensitivity of an Ion Sensitive Field Effect transistor (ISFET) sensor can be significantly enhanced. Our theory and simulations show that by using pH buffer solutions containing counter-ions that are beyond a specific size, the sensor shows significantly higher sensitivity which can exceed the Nernst limit. We validate the theory by measuring the pH response of an extended gate ISFET pH sensor. The consistency and reproducibility of the measurement results have been recorded in hysteresis free and stable operations. Different conditions have been tested to confirm the accuracy and validity of our experiment results such as using different solutions, various oxide dielectrics as the sensing layer and off-the-shelf versus IC fabricated transistors as the basis of the ISFET sensor.
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Affiliation(s)
- Kokab B Parizi
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Xiaoqing Xu
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Ashish Pal
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Xiaolin Hu
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - H S Philip Wong
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
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9
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Minton G, Lue L. The influence of excluded volume and excess ion polarisability on the capacitance of the electric double layer. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1169327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Geraint Minton
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow, UK
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10
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Insight on the effect of surface modification by carbon materials on the Ionic Liquid Electric Double Layer Charge Storage properties. Electrochim Acta 2015. [DOI: 10.1016/j.electacta.2015.06.142] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Kaja M, Silvestre-Alcantara W, Lamperski S, Henderson D, Bhuiyan LB. Monte Carlo investigation of structure of an electric double layer formed by a valency asymmetric mixture of charged dimers and charged hard spheres. Mol Phys 2014. [DOI: 10.1080/00268976.2014.968651] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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Zhou S, Lamperski S, Zydorczak M. Properties of a planar electric double layer under extreme conditions investigated by classical density functional theory and Monte Carlo simulations. J Chem Phys 2014; 141:064701. [DOI: 10.1063/1.4892415] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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13
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Costa R, Pereira CM, Silva F. Electric double layer studies at the interface of mercury–binary ionic liquid mixtures with a common anion. RSC Adv 2013. [DOI: 10.1039/c3ra40584b] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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14
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Bhuiyan LB, Lamperski S. On the interfacial capacitance of an electrolyte at a metallic electrode around zero surface charge. Mol Phys 2012. [DOI: 10.1080/00268976.2012.745954] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Lutful Bari Bhuiyan
- a Laboratory of Theoretical Physics, Department of Physics , University of Puerto Rico , San Juan , Puerto Rico 00931-3343
| | - Stanisław Lamperski
- b Department of Physical Chemistry, Faculty of Chemistry , Adam Mickiewicz University in Poznań , Umultowska 89b, 61-614 Poznań
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15
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Vibhu I, Modak B, Patra CN, Ghosh SK. Zeta potential of colloidal particle in solvent primitive model electrolyte solution: a density functional theory study. Mol Phys 2012. [DOI: 10.1080/00268976.2012.728637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Vatamanu J, Borodin O, Smith GD. Molecular Insights into the Potential and Temperature Dependences of the Differential Capacitance of a Room-Temperature Ionic Liquid at Graphite Electrodes. J Am Chem Soc 2010; 132:14825-33. [DOI: 10.1021/ja104273r] [Citation(s) in RCA: 265] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jenel Vatamanu
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Oleg Borodin
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Grant D. Smith
- Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112, United States
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17
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Guerrero-García GI, González-Tovar E, Chávez-Páez M, Lozada-Cassou M. Overcharging and charge reversal in the electrical double layer around the point of zero charge. J Chem Phys 2010; 132:054903. [DOI: 10.1063/1.3294555] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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18
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Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions. Adv Colloid Interface Sci 2009; 152:48-88. [PMID: 19879552 DOI: 10.1016/j.cis.2009.10.001] [Citation(s) in RCA: 427] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 09/29/2009] [Accepted: 10/01/2009] [Indexed: 11/22/2022]
Abstract
The venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e approximately 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V approximately 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the "compact layer" and "shear plane" effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions.
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Guerrero-García GI, González-Tovar E, Chávez-Páez M. Simulational and theoretical study of the spherical electrical double layer for a size-asymmetric electrolyte: the case of big coions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:021501. [PMID: 19792127 DOI: 10.1103/physreve.80.021501] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2009] [Indexed: 05/28/2023]
Abstract
Monte Carlo simulations of a spherical macroion, surrounded by a size-asymmetric electrolyte in the primitive model, were performed. We considered 1:1 and 2:2 salts with a size ratio of 2 (i.e., with coions twice the size of counterions), for several surface charge densities of the macrosphere. The radial distribution functions, electrostatic potential in all the space and at the Helmholtz surfaces, and integrated charge are reported. We compare these simulational data with original results obtained from the Ornstein-Zernike integral equation, supplemented by the hypernetted chain-hypernetted chain (HNC-HNC) and hypernetted chain-mean spherical approximation (HNC-MSA) closures, and with the corresponding calculations using the modified Gouy-Chapman and unequal-radius modified Gouy-Chapman theories. The HNC-HNC and HNC-MSA integral equations formalisms show good concordance with Monte Carlo "experiments," whereas the notable limitations of point-ion approaches are evidenced. Most importantly, the simulations confirm our previous theoretical predictions of the nondominance of the counterions in the size-asymmetric spherical electrical double layer [J. Chem. Phys. 123, 034703 (2005)], the appearance of anomalous curvatures at the outer Helmholtz plane, and the enhancement of the charge reversal and screening at high colloidal surface charge densities due to the ionic size asymmetry.
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Affiliation(s)
- G Iván Guerrero-García
- Instituto de Física, Universidad Autónoma de San Luis Potosí, 78000 San Luis Potosí, S.L.P., México
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20
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Partenskii MB, Jordan PC. "Squishy capacitor" model for electrical double layers and the stability of charged interfaces. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:011112. [PMID: 19658658 DOI: 10.1103/physreve.80.011112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Indexed: 05/28/2023]
Abstract
Negative capacitance (NC), predicted by various electrical double layer (EDL) theories, is critically reviewed. Physically possible for individual components of the EDL, the compact or diffuse layer, it is strictly prohibited for the whole EDL or for an electrochemical cell with two electrodes. However, NC is allowed for the artificial conditions of sigma control, where an EDL is described by the equilibrium electric response of electrolyte to a field of fixed, and typically uniform, surface charge-density distributions, sigma. The contradiction is only apparent; in fact local sigma cannot be set independently, but is established by the equilibrium response to physically controllable variables, i.e., applied voltage phi (phi control) or total surface charge q (q control). NC predictions in studies based on sigma control signify potential instabilities and phase transitions for physically realizable conditions. Building on our previous study of phi control [M. B. Partenskii and P. C. Jordan, Phys. Rev. E 77, 061117 (2008)], here we analyze critical behavior under q control, clarifying the basic picture using an exactly solvable "squishy capacitor" toy model. We find that phi can change discontinuously in the presence of a lateral transition, specify stability conditions for an electrochemical cell, analyze the origin of the EDL's critical point in terms of compact and diffuse serial contributions, and discuss perspectives and challenges for theoretical studies not limited by sigma control.
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Affiliation(s)
- Michael B Partenskii
- Department of Chemistry, Brandeis University, P.O. Box 549110, MS-015, Waltham, Massachusetts 02454-9110, USA.
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21
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di Caprio D, Holovko M. Spontaneous Polarization of the Neutral Interface for Valence Asymmetric Coulombic Systems. J Phys Chem B 2009; 113:2006-12. [DOI: 10.1021/jp8086573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- D. di Caprio
- Laboratory of Electrochemistry and Analytical Chemistry, University Paris 6, CNRS, ENSCP, Université Paris 6, B.P. 39 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - M. Holovko
- Institute for Condensed Matter Physics, National Academy of Sciences, 1 Svientsitskii Str., 79011 Lviv, Ukraine
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22
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Silva F, Gomes C, Figueiredo M, Costa R, Martins A, Pereira CM. The electrical double layer at the [BMIM][PF6] ionic liquid/electrode interface – Effect of temperature on the differential capacitance. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.05.014] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Alawneh M, Henderson D, Outhwaite C, Bhuiyan L. The effect of dielectric polarization of the electrode on anomalous temperature effects in the electrical double layer. MOLECULAR SIMULATION 2008. [DOI: 10.1080/08927020701654635] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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24
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Outhwaite C, Bhuiyan L. The modified Poisson–Boltzmann electric double layer capacitance for point ions at low temperatures. J Electroanal Chem (Lausanne) 2007. [DOI: 10.1016/j.jelechem.2007.05.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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25
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Madurga S, Martín-Molina A, Vilaseca E, Mas F, Quesada-Pérez M. Effect of the surface charge discretization on electric double layers: A Monte Carlo simulation study. J Chem Phys 2007; 126:234703. [PMID: 17600431 DOI: 10.1063/1.2741520] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The structure of the electric double layer in contact with discrete and continuously charged planar surfaces is studied within the framework of the primitive model through Monte Carlo simulations. Three different discretization models are considered together with the case of uniform distribution. The effect of discreteness is analyzed in terms of charge density profiles. For point surface groups, a complete equivalence with the situation of uniformly distributed charge is found if profiles are exclusively analyzed as a function of the distance to the charged surface. However, some differences are observed moving parallel to the surface. Significant discrepancies with approaches that do not account for discreteness are reported if charge sites of finite size placed on the surface are considered.
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Affiliation(s)
- Sergio Madurga
- Theoretical Chemistry Research Centre (CeRQT) of Scientific Park of Barcelona (PCB), C/Josep Samitier 1-5, E-08028 Barcelona, Catalonia, Spain
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26
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Alawneh M, Henderson D. Monte Carlo simulation of the double layer at an electrode including the effect of a dielectric boundary. MOLECULAR SIMULATION 2007. [DOI: 10.1080/08927020601054068] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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27
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Martín-Molina A, Maroto-Centeno JA, Hidalgo-Alvarez R, Quesada-Pérez M. Testing one component plasma models on colloidal overcharging phenomena. J Chem Phys 2007; 125:144906. [PMID: 17042649 DOI: 10.1063/1.2357945] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this paper, the mechanisms of overcharging of a colloidal macroion in the presence of multivalent counterions are investigated by means of Monte Carlo simulations. This computational technique appears as a powerful tool for probing the validity of semianalytical models developed for this issue. In particular, the simulations performed are compared with the predictions of two different models based on the one component plasma (OCP) theory. Therein, the multivalent ionic atmosphere confined at the macroion surface is approximated by a two-dimensional Wigner crystal. These kinds of models are largely used in the literature since (in some cases) they present quite simple equations to describe the electric double layer (EDL) of macroions with different geometries in the presence of much smaller (but still multivalent) ions. In this sense, charge inversion phenomena of membranes, polyelectrolytes, DNA molecules, etc., are straightforwardly predicted in terms of these expressions. Unfortunately, comparisons between these predictions and experimental results are scarce, mostly due to the difficulty to reproduce the experimental conditions in the laboratory. Accordingly, the goal of the present paper is to simulate EDLs under real conditions (in which overcharging phenomena are expected to happen) and use the results obtained in this way for comparing with those obtained from OCP models.
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Affiliation(s)
- Alberto Martín-Molina
- Grupo de Física de Fluidos y Biocoloides, Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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28
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The capacitance of the electrical double layer of valence-asymmetric salts at low reduced temperatures. J Mol Liq 2007. [DOI: 10.1016/j.molliq.2006.08.033] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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29
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Kilic MS, Bazant MZ, Ajdari A. Steric effects in the dynamics of electrolytes at large applied voltages. I. Double-layer charging. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:021502. [PMID: 17358343 DOI: 10.1103/physreve.75.021502] [Citation(s) in RCA: 341] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Indexed: 05/07/2023]
Abstract
The classical Poisson-Boltzmann (PB) theory of electrolytes assumes a dilute solution of point charges with mean-field electrostatic forces. Even for very dilute solutions, however, it predicts absurdly large ion concentrations (exceeding close packing) for surface potentials of only a few tenths of a volt, which are often exceeded, e.g., in microfluidic pumps and electrochemical sensors. Since the 1950s, several modifications of the PB equation have been proposed to account for the finite size of ions in equilibrium, but in this two-part series, we consider steric effects on diffuse charge dynamics (in the absence of electro-osmotic flow). In this first part, we review the literature and analyze two simple models for the charging of a thin double layer, which must form a condensed layer of close-packed ions near the surface at high voltage. A surprising prediction is that the differential capacitance typically varies nonmonotonically with the applied voltage, and thus so does the response time of an electrolytic system. In PB theory, the differential capacitance blows up exponentially with voltage, but steric effects actually cause it to decrease while remaining positive above a threshold voltage where ions become crowded near the surface. Other nonlinear effects in PB theory are also strongly suppressed by steric effects: The net salt adsorption by the double layers in response to the applied voltage is greatly reduced, and so is the tangential "surface conduction" in the diffuse layer, to the point that it can often be neglected compared to bulk conduction (small Dukhin number).
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Affiliation(s)
- Mustafa Sabri Kilic
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Bhuiyan LB, Outhwaite CW, Henderson D. Planar electric double layer for a restricted primitive model electrolyte at low temperatures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:10630-4. [PMID: 17129040 DOI: 10.1021/la060425k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Monte Carlo simulation and the modified Poisson-Boltzmann theory are used to investigate the planar electric double layer for a restricted primitive model electrolyte at low temperatures. Capacitance as a function of temperature at low surface charge is determined for 1:1, 2:2, 2:1, and 3:1 electrolytes. Negative adsorption can occur for 1:1 electrolytes at low surface charge with low electrolyte concentration. The 1:1 electrolyte diffuse layer potential as a function of surface charge displays a maximum at low densities. At high densities, the diffuse layer potential is negative with a negative slope. The Gouy-Chapman-Stern theory fails in this low-temperature regime, whereas the modified Poisson-Boltzmann theory is fairly successful in this regard.
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Affiliation(s)
- L B Bhuiyan
- Laboratory of Theoretical Physics, Department of Physics, University of Puerto Rico, San Juan 00931-3343, Puerto Rico. beena.beena.cnnet.clu.edu
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Di Caprio D, Valiskó M, Holovko M, Boda D. Anomalous temperature dependence of the differential capacitance in valence asymmetric electrolytes. Comparison of Monte Carlo simulation results and the field theoretical approach. Mol Phys 2006. [DOI: 10.1080/00268970600976774] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Di Caprio D, Badiali JP, Stafiej J. Field theoretical description of the liquid state. Exact relations. The role of the ideal entropy revisited. Mol Phys 2006. [DOI: 10.1080/00268970601014815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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