The faradaic current
that is obtained with a solution containing two substances B
may exceed the sum of the faradaic currents that would be obtained with B
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.
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
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
. In either case the magnitude of the catalytic current depends on the applied potential
. If the current observed with a mixture of A
is smaller than the sum of the separate currents, the term non-additive
current should be used.
PAC, 1985, 57, 1491
(Recommended terms, symbols, and definitions for electroanalytical chemistry (Recommendations
on page 1494