Issue 39, 2020

How to polarise an interface with ions: the discrete Helmholtz model

Abstract

The distribution of electrolytes in an electric field usually relies on theories based on the Poisson–Boltzmann formalism. These models predict that, in the case of a metallic electrode, ionic charges screen the electrode potential, leading to concentration-dependent ion distributions. This theoretical framework was first applied at solid–liquid interfaces and then transposed to soft interfaces. However, in this latter case, the potential in which the electrolytes evolve is not homogeneous, which is less amenable to a mean-field description. In this report, we show that at polarised soft interfaces the potential difference takes place between two closely interacting ionic monolayers. In this configuration, ions of opposite charges directly neutralise each other leading to an absence of diffuse layers and charge screening by surrounding ions. Thus, independently of the electrolyte concentrations, the surface charge density is a linear function of the potential difference, which results in a constant capacitance.

Graphical abstract: How to polarise an interface with ions: the discrete Helmholtz model

Supplementary files

Article information

Article type
Edge Article
Submitted
05 feb. 2020
Accepted
16 maí 2020
First published
18 maí 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2020,11, 10807-10813

How to polarise an interface with ions: the discrete Helmholtz model

G. C. Gschwend, A. Olaya and H. H. Girault, Chem. Sci., 2020, 11, 10807 DOI: 10.1039/D0SC00685H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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