ELECTROCHEMISTRY WITH AN INVERTED ELECTROCHEMICAL CELL
Keywords:electrochemical cell, external working electrode, electrochemical sensor
Microcapillary electrochemical cell has been proven to be a suitable experimental arrangement for a variety of electrochemical applications, such as solid-state electrochemical measurements, meniscus-confined three-dimensional electrodeposition, and corrosion studies. With such experimental system the electrochemical experiment is made by using supporting electrolyte in a microcapillary (commonly with a diameter less than 1000 μm) that is in contact with the surface of an external working electrode. Yet, there are still technical limitations of the microcapillary system to be overcome in terms of high electrical resistance, low reproducibility, complexity and costly instruments (e.g., piezo-positioning system, optical microscope, camera etc.).
Herein we report on a simple, novel experimental arrangement of an electrochemical experiment with the use of an inverted electrochemical cell. Although principally similar to microcapillary system, the proposed arrangement consists of a simple, inverted macroscopic electrochemical cell, being in a contact with a large, externally positioned working electrode. The contact with the working electrode is made by meniscus of a droplet hanging out of the macroscopic capillary ending of the cell. Macro-reference and counter electrodes were inserted inside the inverted electrochemical cell, demonstrating that there is no need for using microelectrodes and complex electrochemical setup. Without using any sophisticated instrumentation it has been shown that there is no significant electrochemical resistance compared to a common electrochemical experiment, while the reproducibility of voltammetric measurements was quite satisfactory. With a preliminary set of experiments under conditions of cyclic voltammetry it is demonstrated that the inverted electrochemical cell is a versatile experimental tool to be used as a scanning probe to study the morphology of the underlying substrate acting as a working electrode, as well as for detection of immobilized solid microparticles. Moreover, the proposed cell is a highly suited system for detection of gaseous species, as exemplified with sensing of gaseous H2O2, which is of exceptional importance for medical applications and for detection of hydrogen peroxide based explosives.
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