Hello,
I'm trying to run a series of electrochemical measurement in a pH7.4 PBS buffer. Since there will be an oxygen and hydrogen evolution reaction at certain points, I need to first purge my buffer with high-purity nitrogen (As suggested by my advisor). I have some questions regarding this:
1) Is purging the PBS at 200 sccm ultra high-purity nitrogen for 1 hour enough? Or is it too much? I did 1 hour per 100 mL of buffer, so if I were to purge 400 mL at once, I'll do 4 hours?
2) I usually purge once right before my experiments, then I don't purge it again until I need to do my next set of experiments. Should I purge it more often? (Like in between experiments to ensure I have no oxygen in the system?) One set of experiments typically lasts a couple hours, sometimes longer.
3) There isn't any faradaic reactions going on, so does this mean I can keep using the same solution over and over, as long as I purge it before experiments?
Thank you very much in advance!!
Ar would be better than N2. O2 is well seen electrochemically on Pt-electrode (Glassy carbon also sees it) at negative potential domain. Run CV under air, then purge the solution by N2/Ar and see that one peak will disappear. Thus you can determine how long you need to purge your solution. During experiment keep the headspace purging with an inert gas
1) You can determine purge time with N2 by using bare electrode. If you don't see O2 peak at approximately -1V, you can use your system.
2) If you send to purge N2 on electrolyte three electrode system during experiment and you don't see boubles on the working electrode, you can't often send in electrolyte to N2. 2 - 3 hours are normally time.
3) if you study in a glowbox system isolated from O2, you can do it.
One simple thing cab be done is run CV on bare electrode and see any oxygen peak in negative potential side (-1V). If there is a peak you need to purge N2 for some time (say 10 Min) then again run CV. If peak disappears then no need to purge more N2.
Thank you for your answers!! I will try these and come back if I have more questions.. :)
As recommended by all experts, as mentioned above, you can follow the peak corresponds to O2 to determine the time. Though i think that 20-30 mins would be enough. Also, you can keep on purging the headspace of your electrochemical cell during your experiments to guarantee inert atmosphere and don't need to purge again and again.
Kind Regards
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