2377
EFFECTS OF HOMOGENEOUS REDOXEQUILIBRIUM IN CYCLIC VOLTAMMETRY
Nuances of the ECE Mechanism.
111. Effects of Homogeneous
Redox Equilibrium in Cyclic Voltammetryl by Stephen W. Feldberg Brookhacen h’ational Laboratory, Upton, New York 11978
(Received January 7, 1971)
Publication costs assisted b y Brookhaven National Laboratory
The ECE mechanism is generally presented as: e-
+ A JrB (1) ;
+ C -D (3). It has fi, B+C A + D (4); k-
B -%= C (2) ; e-
been demonstrated previously that it is necessary to consider the redox reaction: 4 which is related to the Eo’s of reactions 1 and 3 according to: K 4 = k4/k-4 = exp{(F/RT)(E30- El0)] ( 5 ) . The objective of this theoretical study is a qualitative assessment of the effect of reaction 4 on cyclic voltammograms of systems exhibiting ECE behavior. Two limiting conditions are assigned to reaction 4: (A) equilibrium is always maintained or (B) attainment of equilibrium is infinitely slow. The effects of these two limiting conditions are observed in theoretical cyclic voltammograms of three representative ECE situations: (1) E30 = El0 0.3V [&(=lo6) >> 11; (2) ,738 = El0 ( K 4 = 1); (3) E30 = El0 - 0.3 V [ K 4
