Incorporating ion-specific van der Waals and soft repulsive interactions in the Poisson–Boltzmann theory of electrical double layers

Seal, Aniruddha; Tiwari, Utkarsh; Gupta, Amit; Rajan, Ananth Govind

doi:10.1039/d3cp00745f

Cited by 3 publications

(2 citation statements)

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“…54,91 We note that more recent analytical theories/models that incorporate ion–ion correlations and non-electrostatic interactions have been shown to provide more accurate descriptions of EDLs and reproduce capacitance profiles in qualitatively better agreement with experimental capacitance data. 87–90 We also note that previous MD studies on voltage-modulated restructuring of IL double layers have shown significant variation in reorientation of the innermost ions from different surface roughness scales, 40,41 However, the influence of the corresponding innermost ion structuring on like-ion pairing and ion separation is yet to be evaluated for ILs at different nanostructured electrode interfaces. The goal of our present work is to systematically elucidate how the constraint on innermost ions alters the structure and capacitance of IL double layers when electrode surface roughness matches the ion size/structure of the IL.…”

Section: Introductionmentioning

confidence: 89%

“…Theoretical [87][88][89][90] and computational work [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] has helped predict and provide insight into the structure, ion correlation, and properties of EDLs. 54,91 We note that more recent analytical theories/models that incorporate ion-ion correlations and nonelectrostatic interactions have been shown to provide more accurate descriptions of EDLs and reproduce capacitance profiles in qualitatively better agreement with experimental capacitance data.…”

Section: Introductionmentioning

confidence: 99%

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Influence of surface nanostructure-induced innermost ion structuring on capacitance of carbon/ionic liquid double layers

Tu,

Peng

2024

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Influence of surface nanostructure-induced innermost ion structuring on capacitance of carbon/ionic liquid double layers

Tu,

Peng

2024

Phys. Chem. Chem. Phys.

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Ion correlation-driven like-charge attraction in multivalent salt solutions

Agrawal,

Kaur,

Carraro

et al. 2023

The Journal of Chemical Physics

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The electrostatic double layer force is key to determining the stability and self-assembly of charged colloids and many other soft matter systems. Fully understanding the attractive force between two like-charged surfaces remains a great challenge. Here, we apply the modified Gaussian renormalized fluctuation theory to study ion correlation-driven like-charge attraction in multivalent salt solutions. The effects of spatially varying ion correlations on the structure of overlapping double layers and their free energy are self-consistently accounted for. In the presence of multivalent salts, increasing surface charge or counterion valency leads to a short-range attraction. We demonstrate that although both overcharging and like-charge attraction are outcomes of ion correlation, there is no causal relationship between them. Our theory also captures the non-monotonic dependence of like-charge attraction on multivalent salt concentration. The reduction of attraction at high salt concentrations could be a contributing factor toward the reentrant stability of charged colloidal suspensions. Our theoretical predictions are consistent with the observations reported in experiments and simulations.

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Exploring the Impact of Steric Effects on Ion Removal of Water Solutions under the Influence of an Electric Field

Bartzis,

Merlemis,

Ninos

et al. 2024

Water

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In this study, we examine the movement of ions that are in a water solution which flows along a duct, due to the existence of an electric field, taking into account the size of the ions, a phenomenon known as the steric effect. We compare the results from the above model with the classical one (the one that uses the Boltzmann distribution where ions are considered dimensionless) for various parameters such as surface charge density, electric field and differential capacitance. It is shown that for dilute water solutions (1019–1024 ions/m3 final concentration at the center of the duct), with ions of valence z=1 (let us say saline water), steric effects become important for potentials greater than 1 V, and the phenomenon is more pronounced at higher concentrations. Furthermore, the steric effect model is applied to the calculation of the percentage of reduction in ion concentration in the main volume of the solution as a function of duct width for various electrode potentials and initial ion concentrations. Removal times are also calculated using Modified PNP equations which take into account steric effects. It is found that with a potential of 2.6 V, a 96% reduction in ions is achieved in the main volume of the solution for duct width 0.1 mm for 1021 ions/m3 final concentration at the center of the duct within approximately 1.6 s, while the percentage drops to 80% for duct width 1 mm. For smaller potentials, no noticeable decrease in concentration is observed, while for higher potentials, there are more impressive results, but we must be very careful because there is the case of other electrochemical phenomena taking place. The results are better when reducing the width of the duct, but relatively large widths are considered for the method to be practically applicable. With the increase in the concentration of the ions, their reduction percentage in the main volume of the solution decreases but remains significant up to 1023 ions/m3 final concentration at the center of the duct. In addition, the completion time is shown to be proportional to the duct width. Therefore, for example, with the other parameters the same (2.6 V, 1021 ions/m3) but with L~1 mm, the completion time can be estimated to be approximately 16 s. This observation enables us to estimate the completion time for different duct widths, eliminating the need for repeated numerical computation of the MPNP equations.

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Incorporating ion-specific van der Waals and soft repulsive interactions in the Poisson–Boltzmann theory of electrical double layers

Abstract: Electrical double layers (EDLs) arise when an electrolyte is in contact with a charged surface, and are encountered in several application areas including batteries, supercapacitors, electrocatalytic reactors, and colloids. Over...

Cited by 3 publications

References 87 publications

Influence of surface nanostructure-induced innermost ion structuring on capacitance of carbon/ionic liquid double layers

Influence of surface nanostructure-induced innermost ion structuring on capacitance of carbon/ionic liquid double layers

Ion correlation-driven like-charge attraction in multivalent salt solutions

Exploring the Impact of Steric Effects on Ion Removal of Water Solutions under the Influence of an Electric Field

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