Catalytic currentIUPAC Term

The faradaic current that is obtained with a solution containing two substances strong B /strong and strong A /strong may exceed the sum of the faradaic currents that would be obtained with strong B /strong and strong A /strong separately, but at the same concentrations and under the same experimental conditions. In either of the two following situations the increase is termed a catalytic current. strong B /strong is reduced or oxidized at the electrode-solution interface to give a product strong B' /strong that then reduces or oxidizes strong A /strong chemically. The reaction of strong B /strong with strong A /strong may yield either strong B /strong or an intermediate in the overall half-reaction by which strong B' /strong was obtained from strong B /strong . In this situation the increase of current that results from the addition of strong A /strong to a solution of strong B /strong may be termed a regeneration current. The presence at the electrode-solution interface of one substance, which may be either strong A /strong or the product strong A' /strong of its reduction or oxidation, decreases the over-potential for the reduction or oxidation of strong B /strong . In either case the magnitude of the catalytic current depends on the applied potential. If the current observed with a mixture of strong A /strong and strong B /strong is smaller than the sum of the separate currents, the term non-additive current should be used.