Nanostructure Determines the Wettability of Gold Surfaces by Ionic Liquid Ultrathin Films.

Francesca Borghi,Paolo Milani,Alessandro Podestà,Cristina Lenardi,Matteo Mirigliano

doi:10.3389/fchem.2021.619432

Abstract

Ionic liquids are employed in energy storage/harvesting devices, in catalysis and biomedical technologies, due to their tunable bulk and interfacial properties. In particular, the wettability and the structuring of the ionic liquids at the interface are of paramount importance for all those applications exploiting ionic liquids tribological properties, their double layer organization at electrified interfaces, and interfacial chemical reactions. Here we report an experimental investigation of the wettability and organization at the interface of an imidazolium-based ionic liquid ([Bmim][NTf2]) and gold surfaces, that are widely used as electrodes in energy devices, electronics, fluidics. In particular, we investigated the role of the nanostructure on the resulting interfacial interactions between [Bmim][NTf2] and atom-assembled or cluster-assembled gold thin films. Our results highlight the presence of the solid-like structured ionic liquid domains extending several tens of nanometres far from the gold interfaces, and characterized by different lateral extension, according to the wettability of the gold nanostructures by the IL liquid-phase.

Highlights

Ionic liquids (ILs) are salts liquid at room temperature that are attracting a great interest in many disciplines for their low vapor pressure, good conductivity, wide electrochemical window and high thermal stability (Seddon, 1997)
In this work we focused on the characterization of a tiny amount of an imidazolium-based ionic liquid ([Bmim] [NTf2]) deposited on gold nanostructured surfaces that are commonly employed as conductive paths and electrodes in devices
The structural properties and the remarkable presence of surface defects, which affect the electrical properties of the gold cluster-assembled thin films, may modify the local electrostatic properties of the surface (Yajadda et al, 2011) and the local wettability of the ionic liquid on the surface, as discussed in Ref

Summary

Introduction

Ionic liquids (ILs) are salts liquid at room temperature that are attracting a great interest in many disciplines for their low vapor pressure, good conductivity, wide electrochemical window and high thermal stability (Seddon, 1997). Nanostructured and porous materials have been employed in order to increase the interfacial area with the ILs, where the interactions occur (Vatamanu et al, 2013). Nanostructured materials deposited in gas phase, as in the case of cluster-assembled thin films produced by Supersonic Cluster Beam Deposition (SCBD) (Wegner et al, 2006), have been proved to be incorporated into microtechnologies and appealing for the fabrication of electrochemical and energy devices thanks to their high and open porosity (Borghi et al, 2019a), that is wet and accessible by the ILs (Bettini et al, 2013; Soavi et al, 2016; Santaniello et al, 2018)

Methods

Results

Conclusion