Hello Chiranjeevi,

By cyclic voltammetry you can use the laviron method. First you need to get the voltammograms in different scan rates, then make a graph of overpotential versus log (scan rate). With this graph you can find the transfer coefficient (α) and then calculate ket.

ket = αnFvc/RT = (1-α)nFva/RT

You can also calculate by chronoamperometry dividing the current by the charge.

But, depending of your system, is better you use the Marcus approach (in this case, probably you will find some problems to estimate the reorgnization energy).

This review can help you understand better (Eckermann, Amanda L., et al. "Electrochemistry of redox-active self-assembled monolayers." Coordination chemistry reviews 254.15 (2010): 1769-1802.)

In this another review, in the topic "Modelling of Electrode Reactions" (Luz, Roberto AS, et al. "Enzyme Biofuel Cells: Thermodynamics, Kinetics and Challenges in Applicability." ChemElectroChem (2014).) you can find more details about Marcus approach.

Best regards

Article Electrochemistry of redox-active self-assembled monolayers. ...

Article Enzyme Biofuel Cells: Thermodynamics, Kinetics and Challenge...

Thanks a lot Roberto Luz

The rate constants at macroelectrodes are typically calculated using the well-known Nicholson method, which is based on the amount of peak separation between the forward and reverse scans in a cyclic voltammogram. However using macro electrodes is susceptible to errors resulting from ohmic polarization and charging currents, which can lead to overstated rate constants. Another way is using steady-state voltammetry which is a powerful method to study electrode processes, by being able to directly measure rapid heterogeneous rate constants. For example, using ultramicroelectrodes, have advantages such as steady-state currents, increased mass transport, and the ability to be used in highly resistive media, can be obtained. Moreover , there is minimal iRu drop and low background currents associated with ultramicroelectrodes. The steady-state current is a result of the radial diffusion at the ultramicroelectrode.

Dear Sabino,

                  Thanks for your response. Can you please send me the protocol (if possible step wise)to calculate the rate constant from steady-state voltammetry.

Have a Great Time, Cheers...

Electroanalytical Methods 

Allen J. BArd, Faulkner

John and Wiley

Agree with the above.