Electrochemical scanning probe microscope (EC-SPM) for the in situ corrosion study of materials: an overview with examples

Abstract

Electro-chemical scanning probe microscope (EC-SPM) is one of the potential surface investigation techniques to study the electrode-electrolyte interface and over, the years, it has significantly contributed to the understanding of the physico-chemical phenomenon of electrochemical process in different electrochemical environments. The ability to probe the local character at the sub-microscopic level of electrode-electrolyte interfaces with potentiostatic control has advanced its applications in various fields of fundamental, and applied, research such as material science, biological science, physical and chemical science, in order to study the structure and dynamic properties of materials and interfaces. Included in such studies are the structure-reactivity of electrode surface, electro-deposition, surface reconstructions, absorption process, process of corrosion initiation, the study of biological substances in nearby physiological conditions and other interfacial surface morphological studies. Out of several interesting applications of EC-SPM, one of the important and interesting fields of study is the process of corrosion initiation of different materials in simulated environments. To date, its applications are wide spread for understanding passive film property, surface dissolution, surface morphological changes prior to corrosion initiation, the efficiency of inhibitors, and many other branches of corrosion science. As EC-SPM continues to play a significant role in comprehending the process of corrosion, it is important to keep up-to-date on the progress made in the recent past. Thus, the basic aim and scope of the present review is to provide the trends and status of corrosion research of various technologically important materials using EC-SPM. The review includes, an introduction to the fundamentals of EC-SPM, instrumententation in commercial equipments, and applications in the field of corrosion research of various technologically important materials in different electrochemical environments. Illustrative examples have been provided from several investigations reported in the field of electrochemical scanning probe microscopy towards addressing the most critical aspects of corrosion. Major emphasis has been given towards passivation, corrosion initiation, material protection using coatings and associated phenomenon. The review mostly focuses on morphological features of various investigations made so far; for more explanation and other allied experimental techniques readers are requested to go through the respective articles.