Electrochemical microscopy

By its very nature, electrochemistry makes a vital contribution to the development of nanoscience. For example, elementary corrosion or electrocrystallization processes modify the appearance and composition of metal/solution interfaces, initially on an atomic scale, before producing obvious repercussions on a nanometric scale. In addition, electrochemistry can be used to generate a wide variety of structures on conductive surfaces, whether crystalline or amorphous, organic, inorganic or metallic, from solutions containing dissolved, ionic or neutral, monoatomic or molecular species. These structures can take the form of more or less sparse localized deposits or uniform thin films. By rigorously controlling deposition conditions (electrochemical parameters, composition of the electrolyte solution used, etc.), electrochemistry provides access, in the region of the electronic conductor/solution interface, to a wide variety of nano-objects (nanoplots, nanowires, nanotubes, nanocrystals, nanoparticles, nanomotives, films of submicronic thickness, etc.), at least one of whose dimensions is limited to a few nanometers. While conventional electrochemical techniques enable the preparation of a wide variety of nano-objects, they also provide access, for example, to direct global or local characterization of electrochemical reactivity and/or the chemical composition of electrochemical interfaces. However, they also enable the study, sometimes indirectly, of a number of properties, such as the metabolism of biological systems (e.g. cells) via the electrochemical detection of its metabolites (especially when these are electroactive, of course).

The local (electro)chemical and topographical properties of a sample can be viewed using Scanning ElectroChemical Microscopy (SECM), invented at the end of the 1980s using a miniaturized electrode as a probe. SECM is in fact a local probe microscopy technique, offering the possibility of imaging the electrochemical reactivity of samples of various kinds, or of locally modifying their properties. It enables the surface of samples to be examined by scanning them with miniaturized electrodes, which collect a signal indicative of the sample's local redox reactivity, giving a micrometric-scale view of the surface. The use of SECM represents a major advance in electrochemistry, made possible by the miniaturization of electrodes and the ability to measure very low currents. It offers a whole range of applications, from in situ electrochemical imaging to local microscopic surface structuring.

The development of SECM began in the late 1980s, simultaneously in two electrochemistry laboratories [1][2]...