**Author details**

ratio increases from 1.00 (for Erev) to 1.27 for Eirr. The anodic and cathodic parts of

measured than three potentials (i.e., E1/4, E1/2 and E3/4) in the zeroth derivative; in addition, the change of the ratio in the first derivative is more sensitive than the ratio

<sup>a</sup> and W½

**3c**, **W½**

q/ΔEc

2a/W1/2

3a/ΔEp

middle peak with values of 0.32 for the two peak-height ratios (ip

0.52, and 1.62 and 0.98 respectively for the irreversible case.

**2a/W1/2**

*In the second and third derivatives*, compared to first derivatives, *asymmetry in the peak shape is more pronounced*, and more than one symmetry parameters are readily obtained, which are given in terms of ratios of different peak-heights, and peakwidths, and peak-potentials; these parameters are based on peak heights (ip

c

**3a/W½**

2c, & ΔEp

for Eirr, Equasi-rev and two chemically coupled processes of CErev and ErevC. With the third derivatives, there are also minor symmetry parameters associated with the

reversible but these ratios are not as simple as the major ones, but changes to 0.22,

From careful analysis of derivatives of voltammetric current-potential curves, it is possible to extract various parameter which are associated with asymmetry of the derivatives associated with various types of electrode mehanisms. Among those parameters, some of them are strongly influenced by electron transfer kinetics and electrode reaction mechanisms associated with a system, and these parameters are particularly useful in elucidating the reaction mechaisms. In particular, the ratios of

*a /ip c*

system is disturbed by other kinetics, breaking the symmetry in the derivatives. The parameters of each particular systems respond differently to each type of electrode process; thus analysis of symmetry parameters can provide much insight to the mechanistic nature of electrochemical systems. A useful master table for such a diagnostic criteria for differentiating several common types of electrode

Several parts of the work have been presented at various conferences including the 3rd Chemical Congress of North America (Toronto, Canada, 1988), the 57th Georgia Academy of Science Meeting (Lawrenceville, GA 1999), the 221st National

(in **Tables 2** and **4**). All of these values become unity (1.00) for the reversible processes, indicating the symmetry in the curves; but they become no longer unity for quasi-reversible/irreversible electron transfer or chemically coupled processes as the shapes become asymmetrical. The results are summarized in **Tables 2** and **4** with all types of types of processes included. Basically, all of the symmetry param-

**2c** and **ΔEp**

**3c**, and **ΔEp**

q), for the 1st derivative (Wq

2a/ΔEp

3a/ W1/2

) in the first derivative can be more conveniently

**2a/ΔEp**

**3a/ΔEp**

3c) are unity for Erev, they become no longer unity

2m, and W1/2

), and the ratios of the anodic to

) and the ratio of the difference in the anodic and

**)** or the anodic and cathodic peak potential dif-

**)** are most sensitive and useful when a simple reversible electron

) and peak potentials (Ep and Ep). Thus,

**2c** are introduced for

1a/Wq

3m and ip

3m) for

2c) and for third derivative

3a/ip

3c/W1/2

**3c** for third derivative

<sup>a</sup> and

1c), and for

3c/ip 3m)

c

*Analytical Chemistry - Advancement, Perspectives and Applications*

in the zeroth derivatives (namely, 27% vs. 14%).

**2a/ip**

**2c**, **W1/2**

**3a/ip**

the peak-width (Wq and Wq

) as well as peak widths (W½

eters for the 0th derivative (ΔE<sup>a</sup>

3a/W½

2a/ip

2c, W1/2

3c, ΔEp

and 1.32 for the two peak-width ratios (W1/2

the anodic to cathodic peak-currents (*ip*

mechanisms is devised and presented.

*a /W½ c*

*/ΔE<sup>c</sup>*

cathodic peak-widths (*W½*

**Acknowledgements**

cathodic peak potentials (*ΔEa*

*-ΔE<sup>c</sup>*

symmetry ratios of **ip**

2nd derivative (ip

**5. Summary**

ference (*ΔEa*

**26**

3c, W½

second derivatives, and **ip**

ip c

(ip 3a/ip

> Myung-Hoon Kim Department of Physical Sciences, Perimeter College, Georgia State University, Dunwoody, USA

\*Address all correspondence to: mkim124@gsu.edu

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
