Scanning Electrochemical Cell Microscopy Platform with Local Electrochemical Impedance Spectroscopy

Abstract

Local electrochemical impedance spectroscopy (LEIS) has been a versatile technology for characterizing local complex electrochemical processes at heterogeneous surfaces. However, further application of this technology is restricted by its poor spatial resolution. In this work, high-spatial-resolution LEIS was realized using scanning electrochemical cell microscopy (SECCM-LEIS). The spatial resolution was proven to be ∼180 nm based on experimental and simulation results. The stability and reliability of this platform were further verified by long-term tests and Kramers−Kronig transformation. With this technology, larger electric double-layer capacitance (C dl ) and smaller interfacial resistance (R t ) were observed at the edges of Ndoped reduced graphene oxide, as compared to those at the planar surface, which may be due to the high electrochemical activity at the edges. The established SECCM-LEIS provides a high-spatial approach for study of the interfacial electrochemical behavior of materials, which can contribute to the elucidation of the electrochemical reaction mechanism at material surfaces.

The new era of high throughput nanoelectrochemistry

“…Single-barrel SECCM is used in a hopping mode protocol: the probe is approached to a pre-defined spot on the sample surface, a measurement is taken when in contact, and then the probe is retracted in order to be repositioned for the next spot. [222][223][224][225] Potentiostatic techniques have been employed to explore heterogeneous electrochemical response at scales that reach tens of nanometers of spatial resolution. Resulting activity maps comprise thousands of individual points, each a voltammetric scan, for example, and reflect the technique's high throughput aspect.…”

“…AC perturbation to the experimental system was also utilized to conduct local EIS measurements, within the confinement of the meniscus cell. 222 While a major focus of SECCM is on electron transfer processes, a new local electrochemical ion (proton) pump mode of SECCM has been developed to image proton transfer across membranes. 219 In this mode, a double-barrel probe, is used so that the meniscus cell can be landed on the membrane irrespective of its ion transfer characteristics.…”

Understanding Localized Corrosion on Metal Surfaces Using Scanning Electrochemical Cell Impedance Microscopy (SECCIM)

“…Existing studies clearly suggest that SECCM has the ability to perform full-scale DC electrochemical polarization to extract localized kinetic properties to pinpoint the origin of corrosion in heterogeneous surfaces. , In fact, the application of SECCM to study corrosion has been explored by Unwin et al However, AC electrochemical polarization such as EIS is less explored using SECCM probes but has an immense potential to enable understanding of the interfacial changes between the metal and electrolyte. , Previously, a combination of SECM and EIS was used to study the surface-dependent electrochemical properties and elucidate the redox and reactive kinetics at the interfaces. − Ramanavicius et al developed a new approach combining SECM with fast Fourier transform EIS (FFT-EIS) to evaluate the interface with slower diffusion kinetics or lower surface area, which has an important application in the biomedical field. − Therefore, it is clear that EIS can be a valuable tool to characterize the changes in charge-transfer resistance due to surface oxidation, for example during the corrosion of two conjoined metals. Herein, we combined conventional SECCM with EIS to develop scanning electrochemical cell impedance microscopy (SECCIM) to deconvolute charge transfer, adsorption, and emergence of resistive oxide films during surface corrosion.…”

“…28,30 In fact, the application of SECCM to study corrosion has been explored by Unwin et al 22 However, AC electrochemical polarization such as EIS is less explored using SECCM probes but has an immense potential to enable understanding of the interfacial changes between the metal and electrolyte. 31,32 Previously, a combination of SECM and EIS was used to study the surfacedependent electrochemical properties and elucidate the redox and reactive kinetics at the interfaces. 33−36 Ramanavicius et al developed a new approach combining SECM with fast Fourier transform EIS (FFT-EIS) to evaluate the interface with slower diffusion kinetics or lower surface area, which has an important application in the biomedical field.…”

Voltammetric Mapping of Hydrogen Evolution Reaction on Pt Locally via Scanning Electrochemical Cell Microscopy

“…This scan mode can be directly applied to the new scan mode reported here to increase the scan speed further. Another benefit of the constant-contact SECCM-CV mode, shared with the hopping can mode, is that the scope of electrochemical techniques can be readily extended beyond voltammetry, which can include chronopotentiometry, differential pulse voltammetry, and electrochemical impedance. − One potential concern of the constant-contact scan is that the droplet is dragged on the substrate during the lateral scan, which might cause the extension of the droplet to the residual electrolyte at the previous locations. Note that the footprint of the constant-contact scan in the scanning electron microscopy will not reveal whether this droplet extension occurs during individual voltammetric measurements.…”