Design and performance of a minielectrochemical cell for spatial resolution of two-dimensional structures

Abstract

Electrochemical measurements on 2-dlmensional layered materials, such as metal dlchalcogenldes and highly ordered pyrolytic graphite, often require Isolation of the crystal edges or defects. Masking the crystal with epoxy may be undesirable since this prevents recleavlng the electrode to expose a fresh surface. A minielectrochemical cell Is presented that allows experiments to be performed In a single drop (1-3 mm diameter) of electrolyte held against the working electrode. The electrochemical behavior and operational considerations of the cell for an aqueous and nonaqueous system are compared. While the aqueous system generally maintains sem-IlnfinHe linear diffusion, the drop geometry In the nonaqueous system Induces thin-layer effects. Although some applications may not be possible, utilization of the cell for semiconductor electrochemistry Is established. Spatially resolved electrochemistry is demonstrated for n-WSe2 and highly ordered pyrolytic graphite.

Semiconductor Ultramicroelectrodes: Platforms for Studying Charge-Transfer Processes at Semiconductor/Liquid Interfaces

“…52 This same aspect complicates the use of scanning electrochemical cell microscopy (SECCM) 53 for making small area semiconductor/ electrolyte contacts. In that method, a small junction is made by wetting a substrate with a microscopic hanging liquid drop that has counter and reference electrodes, as first described by Koval and coworkers 54 and more recently advanced by Unwin and coworkers. 53 The difficulty in controlling the stability, wetting, and spreading of nonaqueous liquids is welldocumented 55 and a major impediment to its use for studying the details of semiconductor electrochemistry.…”