In Situ Scanning Electrochemical Microscopy (SECM) Detection of Metal Dissolution during Zinc Corrosion by Means of Mercury Sphere‐Cap Microelectrode Tips

Abstract

This work presents a scanning electrochemical microscopy (SECM)‐based in situ corrosion probing methodology that is capable of monitoring the release of zinc species in corrosion processes. It is based on the use of Hg‐coated Pt microelectrodes as SECM tips, which offer a wider negative potential range than bare platinum or other noble‐metal tips. This allows for the reduction of zinc ions at the tip to be investigated with low interference from hydrogen evolution and oxygen reduction from aqueous solutions. The processes involved in the corrosion of zinc during its immersion in chloride‐containing solutions were successfully monitored by scanning the SECM tip, set at an adequate potential, across the sample either in one direction or in the X–Y plane parallel to its surface. In this way, it was possible to detect the anodic and cathodic sites at which the dissolution of zinc and the reduction of oxygen occurred, respectively. Additionally, cyclic voltammetry (CV) or constant potential measurements were used to monitor the release of zinc species collected at the tip during an SECM scan.

Characterization of Inherently Chiral Electrosynthesized Oligomeric Films by Voltammetry and Scanning Electrochemical Microscopy (SECM)

“…Further knowledge of the chemical and electrochemical phenomena involved in such systems can be obtained by high spatial resolution electrochemical techniques, such as scanning electrochemical microscopy (SECM) [14]. SECM is a scanning probe technique based on the amperometric signal generated at a microelectrode [15] by a redox-active species in solution (redox mediator), which can perform quantitative local electrochemical experiments for studying heterogeneous and homogeneous reactions and for high-resolution imaging of the chemical reactivity and topography of various surfaces [14][15][16][17].…”

Cathodic Corrosion of Zinc under Potentiostatic Conditions in NaCl Solutions

“…For instance, pH microprobe measurements could bring a direct and in situ confirmation of the locally high degree of alkalinization due to ORR . Scanning vibrating electrode technique and scanning electrochemical microscopy investigations might help gain understanding on the formation of pits, notably during the early stages of polarization ,. Finally potentiostatic investigations could be conducted under thin electrolyte layers so as to compare the results of the present work with those obtained under conditions closer to atmospheric corrosion.…”

In Situ Analytical Techniques for the Investigation of Material Stability and Interface Dynamics in Electrocatalytic and Photoelectrochemical Applications

“…For instance, Souto et al investigated Zn corrosion in aqueous 0.1 m NaCl using a mercury-coated UME, which kinetically inhibited hydrogen evolution at strongly cathodic potentials while also preventing Zn nucleation and deposition on the UME from changing the electrochemically active surface area. [224] Periodic SECM scans monitored the corrosion of the Zn substrate with time, with differences in the electrochemical activity attributed to evolving local characteristics of the metal corrosion process (Figure 12c). [224] Both anodic and cathodic corrosion sites were observed on the substrate, with anodic sites leading to higher UME cathodic current.…”