Ionic structure around polarizable metal nanoparticles in aqueous electrolytes

TL;DR

This paper develops a continuum electrostatic model for polarizable metal nanoparticles in electrolytes, revealing how ion asymmetries induce phenomena like charge separation and zero surface-charge double layers.

Contribution

It introduces a novel continuum-based model incorporating nanoparticle polarizability and uses multiple theoretical approaches with simulations to explore electrostatic behaviors.

Findings

Ion asymmetries lead to charge separation.

Formation of zero surface-charge double layer.

Electrostatic principles depend on electrolyte composition.

Abstract

Metal nanoparticles are receiving increased scientific attention owing to their unique physical and chemical properties that make them suitable for a wide range of applications in diverse fields, such as electrochemistry, biochemistry, and nanomedicine. Their high metallic polarizability is a crucial determinant that defines their electrostatic character in various electrolyte solutions. Here, we introduce a continuum-based model of a metal nanoparticle with explicit polarizability in the presence of different kinds of electrolytes. We employ several, variously sophisticated, theoretical approaches, corroborated by Monte Carlo simulations in order to elucidate the basic electrostatics principles of the model. We investigate how different kinds of asymmetries between the ions result in non-trivial phenomena, such as charge separation and a build-up of a so-called zero surface-charge double layer.