Controlled-potential coulometry cell design

Optimization of cell design for controlled-potential coulometry. The... 

A large ohmic potential drop is often present in OTTLE cells owing to the nonuniform current distribution within the thin-layer cavity caused by the large distance between the working electrode and counterelectrode. This is not a problem, as experiments generally involve exhaustive electrolyses, where any ohmic drop can be out-waited . The OTTLE cell design enables the techniques of thin-layer electrochemistry, cyclic voltammetry, controlled potential coulometry and UV-visible spectros-... 

Practically every serious worker in the field of controlled-potential coulometry has, at one time or another, designed an electrolysis cell to fit a particular set of circumstances. Many of these designs have found their way into the literature but, nonetheless, have not stimulated any noticeable commercial production of such apparatus. 

Because controlled-potential coulometry involves heterogeneous processes, the time required for completion of electrolysis will depend on the ratio of solution volume to electrode area. In fact, the rate of electrolysis is inversely proportional to the volume-electrode area ratio provided all other variables are held constant. This has the important experimental consequence that electrolysis rates may be varied without adjusting any of the other parameters, such as temperature or potential, which might influence the mechanism of the electrolytic process. Bard (29) has taken advantage of this fact to design cells of extremely low volume to electrode area ratios for high speed coulometry. 

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