Does size of counter electrode really matter?

1. Does size of counter electrode really matter? It is possible to use any electrode material to construct this type of electrode. The reason is because working electrode behavior does not get affected by its electrochemical properties. Inert electrode is better chosen to ensure no electrolysis-based substances are produced that might reach the surface of the working electrode. Otherwise, it might only cause interfering reactions like carbon and platinum. Size to consider Between Counter Electrode (CE) and working electrode (WE), current tends to flow. Hence, the CE (electron sink or source) total surface area needs to be much larger when compared to WE area. This way, in electrochemical kinetics processes, it is not likely to be a viewed as a limiting factor. It can even be placed within a compartment that is separated by any separator or a sintered-glass disk from the WE. Potentiality factor Working electrode’s potential gets relatively monitored to a separate RE (Reference Electrode), whose tip is positioned closeby. Potential difference controlled by the potentiostat between RE and WE are found to have high input impedance. This is such that through the RE, flow of current is quite negligible. Hence, RE potential is likely to remain equal and constant to open-circuit value. Majority of the electrochemical experiments tend to use this three-electrode arrangement.

2. Use Carbon Electrode is mostly used for closing electrochemical cell’s current circuit. Inert materials like glassy carbon, graphite, Au, Pt, etc. is generally used in its construction. It also hosts redox reaction taking place at CE surface. This, in turn, help balance redox reaction at WE surface. The products created by this reaction have the ability to diffuse with WE while interfering with onsite redox reaction. But electroanalytical experiments like CV (cyclic voltammetry), experiment time scale is found to be excessively short for such diffusion to result in significant interferences. Positioning In the original cell, potential profile mostly is based on the solution conductance, geometry, shapes of the electrode used. In case, the RE is placed at any place but not at the surface of the electrode, then uncompensated potential of a small fraction, iR (resulting from uncompensated resistance, Ru) is likely to get included within measured potential. Usually, some uncompensated resistance remains even if RE tip has been designed to accommodate close placement to, WE by using fine tip.