The CV shown is not very well defined. It seems that you have a lot of capacitive currents and/or a working electrode of too big surface area. A CV of the background electrolyte could help to clarify this point. Concerning your "peaks", A1 and A2 could be the couple you are looking for, although the current of A2 should be negative in a good quality voltammogram... B1 seems to be part of a second peak (excursion to more positive potentials could help to define it), but B2 seems not a peak at all...

Can you specify electrolyte? and pH?

You must tell us the electrolyte using  and the pH in this experiment .

From the nature of reaction between the metallic material and composition of electrolyte, can be know the reactions that occur on cathodic and anodic sites from the peaks which appear on the upper and lower curves. Also if you need can provide you with some papers which help you to identify the nature of reactions.

The composition of electrolyte is 10 mM LiI, 1 mM I2 in acetonitrile solution containing 0.1 M LiClO4 as the supporting electrolyte. ph was 4-5 and the scan rate is 20 mV sec-1. I shall be glad to have you answer. Thanks in advance.

Please, See:

And compare with your conditions and do not forget they have Redox Potentials of the iodine-iodide system and their relative electrochemical potentials in acetonitrile solutions versus the normal hydrogen electrode, NHE.

Also, one CV with not full potential diapason is not enough for such analysis.

 Good Luck

Kostyantyn Kylyvnyk thanks I will have a look at it and consider your suggestion

A1 and A2

The redox behavior in a Triiodide/iodide based electrolyte is basically containing two redox peaks corresponding to the following reactions:

3I-→I3- + 3e  (at more negative potentials)

2I3-→3I2 + 2e (at more positive potentials)

I think you could have a negative shift in your peaks due to adsorption of iodide on your surface. I may say, peaks B1-A2 for second reaction and peaks A1-B2 for first reaction. So, you might increase your potential window and see if you will observe clearer peaks.

see also, PCCP [2009, 11(18):3375-3379]

The CV shown is not very well defined. It seems that you have a lot of capacitive currents and/or a working electrode of too big surface area. A CV of the background electrolyte could help to clarify this point. Concerning your "peaks", A1 and A2 could be the couple you are looking for, although the current of A2 should be negative in a good quality voltammogram... B1 seems to be part of a second peak (excursion to more positive potentials could help to define it), but B2 seems not a peak at all...

Thank you very much all for your input. Actually I had to show that  my electrode material shows good electro-chemical activity towards reduction of triodide in a DSSC. But I had to assign anodic and cathodic current peaks, rightly said by Juan Casado that A2 should have been negative to show good ECA. 

You might want to re-record the CV, also record a background CV. Once you obtain a background corrected CV, the peaks may be more enhanced. Based on your CV, the anodic and cathodic current peaks can be obtained directly from the peak A1 and A2 respectively.

A1 and A2 are peaks corresponding to redox reaction.

B1 and B2 are points which represents the potential window for your CV.

The CV shown is not very well defined. It seems that you have a lot of capacitive currents and/or a working electrode of too big surface area. A CV of the background electrolyte could help to clarify this point. Concerning your "peaks", A1 and A2 could be the couple you are looking for, although the current of A2 should be negative in a good quality voltammogram... B1 seems to be part of a second peak (excursion to more positive potentials could help to define it), but B2 seems not a peak at all... p