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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Differential capacitance of an electrical double layer with asymmetric ion sizes in the presence of hydration interactions

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Bossa, V, Guilherme ; Caetano, Daniel L. Z. [1] ; de Carvalho, Sidney J. [1] ; May, Sylvio [2]
Total Authors: 4
[1] Bossa, Guilherme, V, Sao Paulo State Univ UNESP, Dept Phys, Inst Biosci Humanities & Exact Sci, Sao Jose Do Rio Preto - Brazil
[2] North Dakota State Univ, Dept Phys, Fargo, ND 58108 - USA
Total Affiliations: 2
Document type: Journal article
Source: Electrochimica Acta; v. 321, OCT 20 2019.
Web of Science Citations: 0

The differential capacitance is a fundamental property of an electrical double layer and thus important for the development of more efficient and environment-friendly energy storage devices. In addition to the bare electrostatic interactions, the differential capacitance is affected by a complex interplay of ion-specific effects that arise from ion size, shape, and hydration. We employ Monte Carlo simulations to calculate the differential capacitance for size-asymmetric spherical ions, thereby modeling hydration-mediated interactions using Yukawa pair potentials. We also propose a corresponding mean-field theory that includes ion-specific Yukawa pair potentials and accounts for ion size mismatch on the basis of a recently proposed lattice model. Comparison of the two approaches - Monte Carlo simulations and mean-field theory - yields qualitative agreement, irrespective of ion size and size mismatch between cations and anions. The agreement includes the regime of weakly charged electrodes, where we find a growing differential capacitance with growing ion sizes, a behavior that is not consistent with the widely used Stern layer concept. Hence, our study reinforces the predictive power of mean-field theory, but only when the influence of correlations due to excluded volume interactions is diminished by the presence of soft, hydration-mediated ion-ion interactions. (C) 2019 Elsevier Ltd. All rights reserved. (AU)

FAPESP's process: 17/21772-2 - Extensions of the Poisson-Boltzmann Theory to the study of the differential capacitance of an electrical double layer
Grantee:Guilherme Volpe Bossa
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 18/01841-2 - Computational Simulation Studies on the Interaction Between Polyelectrolytes and Macromolecules
Grantee:Sidney Jurado de Carvalho
Support type: Regular Research Grants