1. Randles-Ševčík Equation
There are many resources that describe the detailed background, derivation, and applications of the Randles-Ševčík equation1-5.
Here, we present just a snippet to get you started.
In a voltammetric experiment where a potential sweep is applied to the working electrode using a potentiostat (e.g., LSV
or CV), the peak current 
observed for a voltammogram follows the Randles-Ševčík equation,
(1)where 
is Faraday’s constant, 
is the universal gas constant, 
is the absolute temperature, 
is the number of electrons involved in the redox half-reaction being studied, 
is the diffusion coefficient for the redox active species, 
is the molar concentration of the redox active species, A is the surface area of the electrode, and \upsilon is the rate at which the potential is being swept.
The Randles-Ševčík equation is often written in an abbreviated form under the assumption that the temperature is fixed at 298.15 K (25℃). For work at this particular temperature, the constants appearing at the beginning of the equation can be combined, allowing the equation to be written more simply as follows:
(2)The constant appearing at the beginning of this simplified version of the equation is understood to have units (e.g., 2.69 × 105 C mol-1V-1/2).
2. References
- Bard, A. J.; Faulkner, L. A. Electrochemical Methods: Fundamentals and Applications, 2nd ed. Wiley-Interscience: New York, 2000.
- Kissinger, P.; Heineman, W. R. Laboratory Techniques in Electroanalytical Chemistry, 2nd ed. Marcel Dekker, Inc: New York, 1996.
- Wang, J. Analytical Electrochemistry, 3rd ed. John Wiley & Sons, Inc.: Hoboken, NJ, 2006.
- Langhus, D. L. Fundamentals of Electroanalytical Chemistry. J. Chem. Educ., 2002, 79(10), 1207.
- Elgrishi, N.; Rountree, K. J.; McCarthy, B. D.; Rountree, E. S.; Eisenhart, T. T.; Dempsey, J. L. A Practical Beginner’s Guide to Cyclic Voltammetry. J. Chem. Educ., 2018, 95(2), 197-206.