CV setup is glassy carbon WE, Pt wire CE, and Ag/AgNO3 RE (no salt bridge). My solvent is DMSO with tetraethylammonium tetrafluoroborate (TEAFB) as the electrolyte. The reference electrode contains 10mM AgNO3 with 100mM TEAFB in DMSO. Solutions are made in a dry anaerobic chamber and the electrochemical cell is continuously purged with argon.
Before performing CV on the redox couple analyte, I condition the electrodes by doing CV with just electrolyte solution, which should generate a flat line (I think). Instead, I am consistently observing very small peaks near 0V.
I was able to measure a reasonable duck plot for ferrocene a week ago, but with fluorene I only see the tiny peaks around 0V, however the signal strength is about 1.5x in that solution (which has 3x the concentration of electrolyte).
How do I troubleshoot this? If it were O2 or some other contaminant, shouldn't the peaks appear somewhere else? Currently I am thinking that something is going on with the electrodes but I don't know what.
Please help, thank you
Firstly, Emerald you are a very good researcher trying to find the best way of doing measurements.
For your problem I can only guess:
1) It is not O2. This wave appears usually somewhere around -1.5 V vs ferrocene, ~-1 V vs AgCl.
2) It could be an impurity in DMSO. Did you distill the DMSO? Can you check for impurities using HPLC?
3) It could also be your working electrode. If you have another at hand, try another electrode, or polish your working electrode.
Cyclic voltammetry is a real hands-on method and you have to take care about many parameters, but it is a very nice and insightful method at the same time. Good Luck.
The first thing is that you need to check your electrode if it's properly clean or not. Also, slightest of the impurities in the blank may result in peaks.
Dear Emerald, I agree with the propositions of Axel and Divyansh.
The problem is probably the WE which is not well cleaned.
To be sure for that, you can simply use the same electrode to record cyclic voltamgrams in another solvent.
It could be that AgNO3 has diffused from your RE to your WE. The peaks would then be the reduction and oxidation of AgNO3 which would occur around 0 V given that your RE has the same half reactions. You also mention there is no salt bridge, which would serve as a barrier to diffusion for the ions. If the peaks get larger with successive cycles, then this could indicate that you have this problem as more AgNO3 diffuses to your WE over time.
Otherwise, it could be impurities in the DMSO or your electrolyte.
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