The Rotating Cone Electrode RConeE

The usefulness of the RDE stimulated the development of several other rotating configurations that are worth mentioning. Some of these have evolved in response to specific experimental needs, whereas others serve as possible extensions of the technique. 

Often bubbles are generated at the electrode surface (e.g., when the reaction being studied is the hydrogen evolution reaction) or reach it from the bulk of the solution from the gas used to deaerate it. A bubble trapped at the surface of the RDE is driven toward its center by centrifugal force. This phenomenon can cause major errors in measurement because (i) part of the surface of the electrode is blocked and (ii) the hydrodynamic flow in the vicinity of the electrode may be greatly distorted. 

A solution to this problem is to use a rotating cone electrode (RConeE). It turns out that RCone electrodes are similar to RDE in that they act as uniformly accessible surfaces, producing a uniform rate of mass transport to all parts of the electrode surface. For a cone having an opening angle of 0, the current density is given by 

When a bubble forms at the rotating cone, it is also driven to its center, namely to the tip of the cone. However, it is in a rather precarious state there, and if it is not dislodged spontaneously by some minor instability in rotation, it can be easily removed. 

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