In three electrode system, we use reference electrode to define absolute (not relative) voltage value of working electrode.
When we use DC input(ex. Linear Sweep Voltammetry), voltage is measured between WE and RE, and current is measured between WE and CE, then compensate IR drop between WE and RE.
But does we measure same V and I in EIS? (V between WE-RE / I between WE-CE)
I think V and I that are measured from different circuit, (Current measuring includes information of CE-electrolyte path that can work as capacitor, and the information is not included in voltage measuring).
Do we not measure V,I of same circuit(WE-RE or WE-CE) when using EIS analysis?
I'll be glad for your any comments.
Dear Th Kim,
in a(ny, standard) three-electrode configuration cell, all, regular, measurements are based on the same (hardware) duplex electrodes' combinations, either
1) in the (pretty much pseudo-DC) LSV (and/or CV), or
2) in the (altogether DC+AC) EIS measurements.
We measured the impendence of solution which we used in three electrode system and the impendence during charge translation.
Reference is always the choice when you want to separate WEs reactions from that of the CE.
If you use a two electrode configuration (connect the RE wire to CE wire) you measure both WEs and CEs impedance in series.
Two electrode configuration can be good if you have high impedance REs or problems with the RE. But then you should have a really huge CE and a very small WE. This mode is more stable and sometimes used when very small currents flow (microelectrodes against a normal reference electrode, which is not polarised due to the very small current). Then you can use the direct output of an impedance measurement device.
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