Ion Pairing Mechanisms in Electrode Processes

The influence of "bulk" ion pairing on electrode processes is easily detected when its main effect is to decrease the activity of the depolarizer. On the other hand, when association with the adsorbed ions of the supporting electrolyte forms a more electroactive entity, it is known that it can be more difficult to distinguish between direct discharge, or via ion pairs. However, a broad intercomparison (under strictly identical experimental conditions) of the influence of the nature and concentration of the supporting cation (Li⁺, Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Ba²⁺) on depolarizers of various electronic charge, allows to detect the abnormal behaviors, which are not determined by the pure "static" π effect. An indirect method has also been used, which essentially consists in modifying the double layer profile by adding, at constant concentration, increasing amounts of tensioactive ions having the same charge as the electrode, e.g., iodide at not too negative charge densities.