We prepared Co-Mo alloy by electrodeposition method. The electro-catalytic activity of Co and Co-Mo coatings for the oxidation of hydrazine was studied in 1 M NaOH solution by Cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). But, the peak corresponding to Co(II)Co(III) oxidation is present in anodic scan of CVs, but there are no any peaks in cathode scan. Why?
Hi.
Many points should be decleard first.
1.is this the first scan, or steady state voltammograms.
2. Why use fast scan rate? please, try different slow scan rates.
3. Why did you choose 0.6V as upper potential limit?
Dear Mehdi Abdolmaleki,
I had a little experience working with Co hydroxide (II). Oxidation of the Co up to 3+ valent state going on quickly (from Co (II)), but reverse process isn't have high speed. That`s why you can observe weak peak or absence of reduction peak at all. Hope, that my answer will help you.
I agree with Valerii.
It depends on the chemical reversibility.
One thing I have noticed is a curve crossing in your CVs.
The curve crossing event in your CV time scale may occur due to instability of the metal complexes and deposition on the electrode.
Ref: The Hydrophilic Phosphatriazaadamantane Ligand in the Development of H 2 Production Electrocatalysts: Iron Hydrogenase Model Complexes
Article in Journal of the American Chemical Society 126(38):12004-14 · October 2004
DOI: 10.1021/ja039394v ·
Hope it helps!
Dear Mehdi
I agree with Alaa
i recommend you to re-perform the work with low sweep rates (5-10 mV/s) and extended upper and lower potential limits, that will surely allow you to answer the questions.in alkaline media, between Co(II)and Co(III) there is a narrow zone corresponding to a stable oxide Co3O4 which is not easy to reduce at such pHs.(attached Pourbaix Diagram)
question: is the solution agitated ?
Best wishes,
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