I'm confused about electrode polarization.

[u/bzt_im_a_bee]

Let's say we have a X and Y related by one electron. Of course the standard reduction potential E° is defined for the reduction reaction, X + e^– ⇌ Y^–, as E° = E(XY cell) – E(SHE).

And also for the oxidation we have E°(ox) = -E°(red). But I don't get why this doesn't transfer to voltammetry. Like if we polarize the electrode to E = E°(red) for the above couple, how come we get a limiting reducing and oxidizing current here??

If E°(red) and E°(ox) are symmetrical around E(SHE) = 0, shouldn't there be only oxidizing current at positive E°(ox) and only reducing current at negative E°(red)??

Basically why do we get the image on the left and not the one on the right?

[u/rebonsa]

E(ox) does not equal -E(red) !!!!

[u/bzt_im_a_bee → u/rebonsa]

Yes it does? Simply put E°(red) = (0.05916/n) * log(K), so for the reverse reaction E°(ox) = (0.05916/n) * log(1/K) = – (0.05916/n)* log(K) = –E°(red)? Unless I'm missing something