Probing Electrified Liquid-Solid Interfaces with Scanning Electron Microscopy

TL;DR

This study demonstrates that scanning electron microscopy can effectively probe and map electrified liquid-solid interfaces by analyzing secondary electron yield variations influenced by electrolyte properties and applied bias.

Contribution

It introduces a novel method using graphene as an electron-transparent electrode to investigate electrical double layers at liquid-solid interfaces with SEM.

Findings

Secondary electron yield depends on electrolyte ionic strength and bias.

Electrochemical polarization affects potential distribution in the double layer.

Method enables visualization of electrified interfaces at nanometer scale.

Abstract

Electrical double layers play a key role in a variety of electrochemical systems. The mean free path of secondary electrons in aqueous solutions is on the order of a nanometer, making them suitable for probing of ultrathin electrical double layers at solid-liquid electrolyte interfaces. Employing graphene as an electron-transparent electrode in a two-electrode electrochemical system, we show that the secondary electron yield of the graphene-liquid interface depends on the ionic strength and concentration of electrolyte and applied bias at the remote counter electrode. These observations have been related to polarization-induced changes in the potential distribution within the electrical double layer and demonstrate the feasibility of using scanning electron microscopy to examine and map electrified liquid-solid interfaces