Oxidation peak always appears at more positive potentials than reduction peak of the same reaction (anodic current-oxidation is positive, cathodic reduction current is negative). If you have multiple oxidation/reduction reactions, peaks, you should take care of which cathodic peak corresponds to anodic.

Hello

The oxidation peak potential appears at lower potential Indicates oxidation reaction is speed and easy. It seems that in your test conditions the oxidation reaction rate is low. You should facilitate the oxidation reaction by specific methods such as using a catalyst.

There are two convections commonly used for reporting CV curves: IUPAC and US convection. These two convections represent the same results by visually they appear to be rotated by 180 degrees. So, you have to be careful about the data reported in the literature. Oxidation peaks always appear at positive currents and reduction peaks always appear at negative currents. I guess the literature you referenced used the US convection - the oxidation peak appeared at negative values, but actually corresponded to positive currents.

Hello Liang Wu

Thank you for your response.

The oxidation peaks appear at positive currents, and the reduction peaks at negative currents, as you mentioned. But, I referred to potential values, no current values. In such case, my oxidation peak appears at positive potential values, while in the literature it is reported at negative potential values, but always at positive current values.

Many thanks also to Zohreh Merati .

Mv Gomez

Was the reference electrode you used the same as that in the literature?

Liang Wu

Thank you very much! Yes, I have checked that the reference electrodes are different! That's must be the point. Many thanks for your help.

Any potential drop (in solution, in the working electrode, in external circuitry) can also move the measured potential at more positive values.