No, I can not help.

I am assuming that you are looking at CV data.  In essence the issue being addressed is whether the electrode reactions are limited by diffusion (electrochemically reversible) or electron transfer kinetics become rate determining (quasi-reversible).  In the limit where the electrode reactions are diffusion controlled, the peak to peak separation should be 59 mV (Nickelson and Shane), but experimentally one usually see 60 to 70 mV peak to peak separation. The Ferrocene redox couple is electrochemically reversible and should probably be used to assess the peak to peak separations. In the limit where EC is negligible, and the electrode reactions are diffusion controlled, the peak to peak separation is a constant independent of scan rate, and plots of the peak currents are linear with respect to the square route of the scan rate. Alternatively, if the scan rates are on the time scale of the electrode kinetics

, the peak to peak separations increase with scan rate the CV  waves broaden.  Ideally one would like to run a separate experiment, or spectro-echem to insure that the species undergoing the electrode reactions are identified as a function of the oxidation state and to insure that there are no coupled side reactions.  Extraction of the heterogeneous electron transfer rate constant may be obtained by modelling the CV using software such as Digism (BAS), or other protocols. A description of the various electrochemical techniques are described In "Electron Transfer in Chemistry" Volume 1 (Ed. V Balzani) page 422 Pederson and Daasbjerg.

Dear Rabeay,

Attached are two files that cover the answer to your question.

Hoping this will be helpful,

Rafik

Laviron's plot method

Hussein Hijazi - I would also use Laviron's method first assuming the mechanism is not complicated. Learning to simulate with software like Digisim is useful but can take some practice.

Thanks everyone, your help is highly appreciated...

I need to find out the heterogeneous electron transfer rate constant for different heterogeneous catalysts by chronoamperometry technique. Please suggest method