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Multiple working / Counter / Reference electrode system

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CoolGuy:
Hello everybody,

I am currently working with a BIOLOGIC SP300 potentiostat, equipped with two channels for working, counter, and reference electrodes, operating in floating mode (each channel having its own ground). My objective is to investigate a metallic deposition process concurrently on two metal electrodes. To achieve this, I attempted to apply an overvoltage relative to a single HgO/Hg reference electrode. In simpler terms, both channels are linked to the same reference electrode, and I endeavored to apply an overvoltage to two distinct metal electrodes with respect to this shared reference electrode.


In my results, which regrettably I cannot share, it appears that the behavior of the first two working/counter electrode pairs is correlated with the second pair through the reference electrode. Both pairs are linked by the electrolyte, but the behavior of the first pair is different than expected. Initially, I assumed it was feasible to apply, for instance, +50mV vs HgO/Hg to both working electrode 1 and working electrode 2 simultaneously. However, I have a sense that it might not be as straightforward as I initially thought.

Your question is straightforward: do you have any general advice regarding this type of configuration (multi-electrode system in the same cell with the same reference electrode)? Are there any hidden behaviors I should consider before proceeding?

Thank you very much and have a nice day,
Sincerely

Borek:
I am trying to understand your setup but details are not clear, can you at least post some simple schematic to show the system? You can attach an image to the post, just keep it below 1MB.

CoolGuy:
Hello Borek, thank you for your prompt response. Please find below a diagram illustrating my setup.

I am applying, for example, +50 mV vs REF on both WE 1 and WE 2, which are connected through both the electrolyte and the reference electrode. Although all channels are in floating mode, it seems that the connection via the electrolyte is quite robust. Have you observed such a phenomenon before?

Borek:

--- Quote from: CoolGuy on January 29, 2024, 09:34:57 AM ---it seems that the connection via the electrolyte is quite robust.
--- End quote ---

I have never worked with such a setup, so I am not pretending to be sure, but just by looking at the circuit - in a way connection by the electrolyte is equivalent to having just resistors between all electrodes, so I don't think they can work independently. Even WE1/WE2 are connected, so if the overvoltages are different I wouldn't be surprised by current flowing between them and interfering with measurements.

CoolGuy:
Thank you for your interesting feedback, Borek. I share your opinion, and I am currently studying these interference phenomena. If I manage to uncover the whole story, I will keep you informed!

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