A Rotating Ring‐Hemispherical Electrode for Electroanalytical Applications

Abstract

A study has been made of the combination of a rotating hemispherical electrode with a ring electrode of a larger radius for use in investigations of reaction intermediates. Cyclic voltammetry in an acid copper solution was used to test the feasibility of the combination, and a ferricyanide/ferrocyanide redox reaction was used to measure the collection efficiency at the ring electrode. The collection efficiency was found to be independent of the rotational speed in laminar flow, and its value was comparable to that obtained from the rotating ring‐disk electrode theory. The results indicate that the ring‐disk theory can be used as a rough approximation for the ring‐hemisphere electrode if the inner radius of the ring electrode is a minimum of 1.08 times the radius of the hemispherical electrode. Easy replacement of the central hemispherical electrode is a big advantage of this new geometry. This offers electrochemists an alternative choice where the use of a ring‐disk electrode would fail to give a meaningful result and where frequent replacement of the disk electrode is needed.