The
faradaic current that is obtained with a solution containing two substances
B and
A may exceed the sum of the faradaic currents that would be obtained with
B and
A 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.
B is reduced or oxidized at the electrode-solution
interface to give a product
B' that then reduces or oxidizes
A chemically. The reaction of
B with
A may yield either
B or an intermediate in the overall half-reaction by which
B' was obtained from
B. In this situation the increase of current that results from the addition of
A to a solution of
B may be termed a regeneration current. The presence at the electrode-solution
interface of one substance, which may be either
A or the product
A' of its reduction or
oxidation, decreases the over-potential for the reduction or
oxidation of
B. In either case the magnitude of the catalytic current depends on the
applied potential. If the current observed with a mixture of
A and
B is smaller than the sum of the separate currents, the term non-
additive current should be used.
Source:
PAC, 1985, 57, 1491
(Recommended terms, symbols, and definitions for electroanalytical chemistry (Recommendations
1985))
on page 1494
