Hi all,
I'm working on OER. I found that with my material (a high surface area electrode), the Tafel slope is much smaller than a low surface area electrode with the same surface. Is that normal? Can someone explain to me the relation between surface area and Tafel slope?
I know that the Tafel slope is closely related to the charge transfer coefficient, which is largely dependant on the charge transfer resistance (is that true?). Does the charge transfer resistance follow this rule?
Resistance = Resistivity * Length / Area
If so, I guess the bigger surface area, the smaller resistance, and thus smaller Tafel slope. Does this make sense?
Tafel equation is derived assuming that a single reversible redox reaction takes place on electrode. OER is more complex process and I doubt that Tafel equation can be used in this case. In addition, it's very important how you measure the current. Theoretically, ohmic resistance must be very small and diffusion (mass transfer) should not affect the current.
Thanks Yurii! I understand that Tafel slope is not a good metric for OER, however it’s been reported in every paper.
I’m measuring it with a 1 mV/s LSV. iR compensation is used to minimize the effect of resistance.
The surface area of an auxiliary electrode must be larger than that of working electrode
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