Scanning Electrochemical Cell Microscopy (SECCM) Chronopotentiometry: Development and Applications in Electroanalysis and Electrocatalysis

Abstract

Scanning electrochemical cell microscopy (SECCM) has been applied for nanoscale (electro)activity mapping in a range of electrochemical systems but so far has almost exclusively been performed in controlled-potential (amperometric/voltammetric) modes. Herein, we consider the use of SECCM operated in a controlled-current (galvanostatic or chronopotentiometric) mode, to synchronously obtain spatially resolved electrode potential (i.e., electrochemical activity) and topographical "maps". This technique is first applied, as proof of concept, to study the electrochemically reversible [Ru-(NH 3 ) 6 ] 3+/2+ electron transfer process at a glassy carbon electrode surface, where the experimental data are in good agreement with well-established chronopotentiometric theory under quasi-radial diffusion conditions. The [Ru(NH 3 ) 6 ] 3+/2+ process has also been imaged at "aged" highly ordered pyrolytic graphite (HOPG), where apparently enhanced electrochemical activity is measured at the edge plane relative to the basal plane surface, consistent with potentiostatic measurements. Finally, chronopotentiometric SECCM has been employed to benchmark a promising electrocatalytic system, the hydrogen evolution reaction (HER) at molybdenum disulfide (MoS 2 ), where higher electrocatalytic activity (i.e., lower overpotential at a current density of 2 mA cm −2 ) is observed at the edge plane compared to the basal plane surface. These results are in excellent agreement with previous controlled-potential SECCM studies, confirming the viability of the technique and thereby opening up new possibilities for the use of chronopotentiometric methods for quantitative electroanalysis at the nanoscale, with promising applications in energy storage (battery) studies, electrocatalyst benchmarking, and corrosion research.

Nanoscale electrochemistry in a copper/aqueous/oil three-phase system: surface structure–activity-corrosion potential relationships

“…All experiments in the SECCM configuration were performed on a home-built scanning electrochemical probe microscopy (SEPM) workstation, as detailed in previous works. 40,44 The main components were an x-y-z piezoelectric positioner (P-611.3S, Physik Instrumente, Germany), a galvanostat (home-built, as described in a previous work, 40 serving as voltage follower), a waveform generator (digital herein, utilized for applying the desired current to the galvanostat) and a data collectioninstrument control system (FPGA card herein). The main setup is schematised in Figure 1a.…”

“…Surface ion release under this condition is then analysed by subsequent "electrochemical titration" of a portion of the released metal ions, by applying a cathodic current and recording the resulting chronopotentiometric curve. 40 This allows the evaluation of intrinsic corrosion susceptibility, in situ, with high spatial-resolution, for the entire range of crystallographic orientations of a polycrystalline metal (co-located EBSD analysis). Chronopotentiometry measurements with and without O 2 present, and the use of an anodic pulse to induce the anodic dissolution (as well as the cathodic measurements mentioned) allow all the key electrochemical processes underpinning localised corrosion to be studied.…”

High‐Resolution Electrochemical Mapping of the Hydrogen Evolution Reaction on Transition‐Metal Dichalcogenide Nanosheets

“…[13a, 19] Thea dvantages of SECCM are that it is ar eproducible and reliable technique for fabricating nanoprobes together with fast electrochemical characterization owing to its small capacitive current [19b] and its ability to prevent sample contamination during scanning. SECCM has been used for visualizing the electrochemical activity of as ingle carbon nanotube, [20] highly oriented pyrolytic graphite (HOPG), [21] 3D structure graphene, [22] polycrystalline Pt, [23] ac leaved 2H-MoS 2 nanosheet, [24] and Fe 4.5 Ni 4.5 S 8 [25] to reveal the relation between their catalytic activities and structural information.…”

Local electrochemical impedance spectroscopy: A window into heterogeneous interfaces

“…In fact, the term local electrochemical techniques encompasses well established methodologies such as the scanning electrochemical microscopy (SECM) [13,14] and related techniques [2,[15][16][17][18] or scanning vibrating probe technique (SVET) [19,20] which have been widely reviewed these last decades. Among these different techniques, the local electrochemical impedance spectroscopy (LEIS) [21][22][23][24][25] is particularly well-adapted to study complex processes occurring at polarized interfaces.…”