A modified Poisson-Boltzmann theory: Effects of co-solvent polarizability

Budkov, Yu. A.; Kolesnikov, A. L.; Киселев, М. Г.

doi:10.1209/0295-5075/111/28002

Cited by 51 publications

(43 citation statements)

References 29 publications

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“…The latter is one of the most important quantities for the electrochemical applications. In a recent work 26 we showed in the framework of the field-theoretical approach that if an electrolyte solution is mixed with some strongly polarizable dielectric co-solvent, then the variation of the differential capacitance becomes the greater the stronger polarizability grows.…”

Section: Introductionmentioning

confidence: 99%

On the theory of electric double layer with explicit account of a polarizable co-solvent

Budkov

Kolesnikov

Киселев

2016

The Journal of Chemical Physics

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We present a continuation of our theoretical research into the influence of co-solvent polarizability on a differential capacitance of the electric double layer. We formulate a modified Poisson-Boltzmann theory, using the formalism of density functional approach on the level of local density approximation taking into account the electrostatic interactions of ions and co-solvent molecules as well as their excluded volume. We derive the modified Poisson-Boltzmann equation, considering the three-component symmetric lattice gas model as a reference system and minimizing the grand thermodynamic potential with respect to the electrostatic potential. We apply present modified Poisson-Boltzmann equation to the electric double layer theory, showing that accounting for the excluded volume of co-solvent molecules and ions slightly changes the main result of our previous simplified theory. Namely, in the case of small co-solvent polarizability with its increase under the enough small surface potentials of electrode, the differential capacitance undergoes the significant growth. Oppositely, when the surface potential exceeds some threshold value (which is slightly smaller than the saturation potential), the increase in the co-solvent polarizability results in a differential capacitance decrease. However, when the co-solvent polarizability exceeds some threshold value, its increase generates a considerable enhancement of the differential capacitance in a wide range of surface potentials. We demonstrate that two qualitatively different behaviors of the differential capacitance are related to the depletion and adsorption of co-solvent molecules at the charged electrode. We show that an additive of the strongly polarizable co-solvent to an electrolyte solution can shift significantly the saturation potential in two qualitatively different manners. Namely, a small additive of strongly polarizable co-solvent results in a shift of saturation potential to higher surface potentials. On the contrary, a sufficiently large additive of co-solvent shifts the saturation potential to lower surface potentials. We obtain that an increase in the co-solvent polarizability makes the electrostatic potential profile longer-ranged. However, increase in the co-solvent concentration in the bulk leads to non-monotonic behavior of the electrostatic potential profile. An increase in the co-solvent concentration in the bulk at its sufficiently small values makes the electrostatic potential profile longer-ranged. Oppositely, when the co-solvent concentration in the bulk exceeds some threshold value, its further increase leads to decrease in electrostatic potential at all distances from the electrode.

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Section: Introductionmentioning

confidence: 99%

On the theory of electric double layer with explicit account of a polarizable co-solvent

Budkov

Kolesnikov

Киселев

2016

The Journal of Chemical Physics

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“…and renormalized dielectric permittivity 76,77 ε r (r) = ε(r) + 4πp 2 3k B T n m (r) (20) have been introduced.…”

Section: Appendix: Derivation Of Electrostatic Free Energy (4)mentioning

confidence: 99%

Polymer chain collapse induced by many-body dipole correlations

2017

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We present a simple analytical theory of a flexible polymer chain dissolved in a good solvent, carrying permanent freely oriented dipoles on the monomers. We take into account the dipole correlations within the random phase approximation (RPA), as well as a dielectric heterogeneity in the internal polymer volume relative to the bulk solution. We demonstrate that the dipole correlations of monomers can be taken into account as pairwise ones only when the polymer chain is in a coil conformation. In this case the dipole correlations manifest themselves through the Keesom interactions of the permanent dipoles. On the other hand, the dielectric heterogeneity effect (dielectric mismatch effect) leads to the effective interaction between the monomers of the polymeric coil. Both of these effects can be taken into account by renormalizing the second virial coefficient of the monomer-monomer volume interactions. We establish that in the case when the solvent dielectric permittivity exceeds the dielectric permittivity of the polymeric material, the dielectric mismatch effect competes with the dipole attractive interactions, leading to polymer coil expansion. In the opposite case, both the dielectric mismatch effect and the dipole attractive interaction lead to the polymer coil collapse. We analyse the coil-globule transition caused by the dipole correlations of monomers within the many-body theory. We demonstrate that accounting for the dipole correlations higher than the pairwise ones smooths this pure electrostatics driven coil-globule transition of the polymer chain.

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“…Experimental , theoretical , and computational studies have shown that ionic liquids exhibit the finite‐size (crowding or steric) effects of ions and electrostatic correlations (overscreening effects). Efforts have been made to capture these effects, especially on the structure and capacitance of electric double layer (EDLs) for ionic liquids .…”

Section: Introductionmentioning

confidence: 99%

Modeling electrokinetics in ionic liquids

et al. 2017

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Using direct numerical simulations, we provide a thorough study regarding the electrokinetics of ionic liquids. In particular, modified Poisson-Nernst-Planck equations are solved to capture the crowding and overscreening effects characteristic of an ionic liquid. For modeling electrokinetic flows in an ionic liquid, the modified Poisson-Nernst-Planck equations are coupled with Navier-Stokes equations to study the coupling of ion transport, hydrodynamics, and electrostatic forces. Specifically, we consider the ion transport between two parallel charged surfaces, charging dynamics in a nanopore, capacitance of electric double-layer capacitors, electroosmotic flow in a nanochannel, electroconvective instability on a plane ion-selective surface, and electroconvective flow on a curved ion-selective surface. We also discuss how crowding and overscreening and their interplay affect the electrokinetic behaviors of ionic liquids in these application problems.

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A modified Poisson-Boltzmann theory: Effects of co-solvent polarizability

Cited by 51 publications

References 29 publications

On the theory of electric double layer with explicit account of a polarizable co-solvent

On the theory of electric double layer with explicit account of a polarizable co-solvent

Polymer chain collapse induced by many-body dipole correlations

Modeling electrokinetics in ionic liquids

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