I am getting only positive current peak for DPV. Is it anodic peak. How to determine the charge on electrode at negative and positive potential? The electrode work as an anode or cathode?
Hi Ajinkya,
For the determination of whether the peak you got is anodic in DPV, i would double check with the peaks of CV of the same compound. In electrolytic cell, if you are using the positive polarity (anodic potential) then this would result in oxidation whereas, negative potential would mean reduction. If yours one is oxidation then it would definitely mean anodic peak.
If you use negative potential, then reduction occurs. This means the species in the solution is gaining electrons from the working electrode. For this to happen, the electrode should be negatively charged so the electrode act as cathode. After reduction, the working electrode will become positive, inducing cathodic current.
In other hand, positive potential would mean oxidation (species lose electrons to the working electrode). So, the electrode needs to be anode (positively charged). After oxidation, the working electrode become negative and induces anodic current.
In summary, oxidation occurs at anode and reduction occurs at cathode.
Hi Ajinkya Dabhade,
I Agree with Arati Biswakarma regarding the anodic and cathodic reactions. Mostly anodic peaks appear when you do a positive scan of the potential (From lower positive or negative potential to higher positive potential).
For calculating the charge on the electrode you may have to calculate the area under the cathodic/anodic curve (Since q = i*t, where q = quantity of charge in Coulombs(C), I = current in amperes, and t = time(s)).
Hope you found your complete answer.
Ajinkya Dabhade
In order to determine nature of working electrode, we need to study its behavior with either CV or LSV. I preferably study every material with CV in the potential window of -1 to 1 volts. If peaks appear after 0 volts then its anodic otherwise cathodic when peaks appear in the negative potential region.
Dear @Abdul Samad Butt,
Anodic peak need not to appear only after 0V. It depends on oxidation potential of the analyte.
The nature of the process depends on the scanning direction: an anodic process for scanning from low potential to high potential and vice versa for a cathodic process.
See here :
https://pineresearch.com/shop/kb/software/methods-and-techniques/voltammetric-methods/differential-pulse-voltammetry-dpv/
(Fig. 9, where the common case is the last one, Invert None).
A positive peak in DPV may also be a simple convention (it depends on the software).
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