Assessment of the electrochemical microcell geometry by local electrochemical impedance spectroscopy of copper corrosion

Perspectives on Corrosion Studies Using Scanning Electrochemical Cell Microscopy: Challenges and Opportunities

Scanning electrochemical cell microscopy (SECCM) allows for electrochemical imaging at the micro- or nanoscale by confining the electrochemical reaction cell in a small meniscus formed at the end of a micro- or nanopipette. This technique has gained popularity in electrochemical imaging due to its high-throughput nature. Although it shows considerable application potential in corrosion science, there are still formidable and exciting challenges to be faced, particularly relating to the high-throughput characterization and analysis of microelectrochemical big data. The objective of this perspective is to arouse attention and provide opinions on the challenges, recent progress, and future prospects of the SECCM technique to the electrochemical society, particularly from the viewpoint of corrosion scientists. Specifically, four main topics are systematically reviewed and discussed: (1) the development of SECCM; (2) the applications of SECCM for corrosion studies; (3) the challenges of SECCM in corrosion studies; and (4) the opportunities of SECCM for corrosion science.

Electrochemical Impedance Spectroscopy in a Droplet of Solution for the Investigation of Liquid/Solid Interface

The local electrochemical behavior of a solid-liquid interface can be studied by electrochemical impedance spectroscopy (EIS). The investigated surface area can be delimited by adding a drop of solution, which forms an interface between the liquid drop and the working electrode, and performing the measurements inside. The size of the drop must be sufficiently small for a simultaneous wettability characterization (from the contact angle measurement) and appropriately large so that wettability is not influenced by the presence of the working and the counter electrode inserted in the droplet. In this work, we showed that EIS measurements can be performed in a solution droplet of 2 to 4 μL, although the electrochemical cell lacks the usual geometry. For our measurements, we studied a model system consisting of a KCl aqueous solution of [Fe(CN)₆]^3-/4- redox couple at a Pt electrode. All the results were compared with those obtained for a bulk configuration. The sessile drop configuration and the EIS response were modeled using finite element method for different electrode sizes and configurations to account for electrochemical kinetics and both current and potential distributions.