Cyclic Voltammetry (CV)

This technique is often used in the initial development of an electrochemical analysis and for studying the mechanism involved in electrode reactions.  It can also be used to study reactions that have widely different reaction rates. CV measures current as a function of time and, consequently, a function of electrode potential programming rate.

                                    Thus,      

                      Where (κ) is a constant,

                                  (n) is the programming rate,

                                 (C) is the concentration,

                             and the other symbols have the meaning previously ascribed

                                      to them.

Let us assume that a reactant R is electrolytically reduced to an intermediate [R], which is rapidly converted, irreversibly, to a product (P) in solution that is electrolytically inactive as shown by the following equation.

Programming rapidly the potential of the working electrode (from a negative to a positive potential), a curve relating current (i) will simulate the reduction of (R) and such a curve is shown in figure 22. A similar curve, but somewhat reduced in magnitude is also shown in figure 22 for the slower program.

Figure 22. Examples of Cyclic Voltammetry

Applying a reverse program a complementary curve is obtained for the fast program but not with the slow scan because most of [R] has had time to be converted to (P). It is clear that cyclic voltammetry can be a useful tool in examining reaction kinetics.