Some electrode materials exhibits redox peak positions in negative voltage region while others exhibits in positive voltage region. For example, the redox peaks of MXene in H2SO4 electrolyte are found in negative voltage region whereas PANI give peaks in positive voltages. So, can we conclude that positions of redox peaks are dependent of surface charge type. Can someone please enlighten me in this regard?
Thanking you.
Dear Dinesh
Some comments from my experience. The index for redox peaks is the half wave potential E_1/2, this is the middle potential of two peaks. It shows the redox property of the redox reaction. for example, the Ni always has a lower E_1/2 than Pt, because Ni is more active. But as you know, the surface charge is normally not connected with redox property, and one system may have multiple redox reactions.
For your case, let me just us one example, PANI has the positive charge because N and adsorb H+. If you want to oxidate PANI, you must give excess potential to remove H+ and expose N for reaction. Now, we have Counterexamples. Al2O3 in acid, has positive charge without oxidation peaks at positive potential range, similarly, if you have an electrode with highly reactive groups and different way to give the charge, it can also have peaks in negative range.
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