HI Alekha, are you sure that it is ORR feature ? It can be some adsorption of some impurities. Is the GC electrode cleaned? More information about electrolyte (pH) and experiment is needed. Maybe, the plots will be welcome. How do you measure electrochemistry with N2 and without electrolyte.

Hello Alekha Tyagi

As Roman Fiala states, can you provide more information and possibly and example voltammogram? Hopefully then we can provide you with a more refined answer.

Jules

I also have the same peak. I think it is oxygen...

Hello Alekha Tyagi and Natalia V. Zolotareva :

As Jules Lloyd Hammond.

Also, do you expose (even a small part of) the WE's electrical (uncovered) contact into (or near[1] to) the electrolyte's solution ?

Alternatively, lower the electrolyte's level (to a minimum level) in order to avoid noise(s), eliminating artifacts, side effect(s) from the WE's electrical contact.

1. Troubleshooting for multi-electrodes' based source of electrochemical noise(s) aided by humidity and/or complex "capillary" like actions.

• Thanks Roman Fiala . I have used a newly purchased GC electrode for this measurement. I am attaching related CV voltammograms.
• I performd the measurement in 0.1M KOH. N2 and O2 gases are purged into the electrolyte during the measurement.
• CV curves details: 1) blank GC electrode in O2 purged KOH electrolyte 2) blank GC electrode in N2 purged KOH electrolyte 3) GC modified with doped cabon catalyst ink in O2 purged KOH electrolyte
• As can be seen, no ORR peak is observed in curve 3.

Thanks Natalia V. Zolotareva . But it should not be there in blank GC electrode that too in N2 purged electrolyte as well.

Thanks Ioannis Samaras . will do that.

Jules Lloyd Hammond - Hope this will provide better insight to the issue.

Dear Alekha Tyagi ,

According to potential it seems to be like oxygen reduction. After N2 purge the current decreases but not that much. Maybe, it was not purged enough. Have you tried argon instead of nitrogen? When you added the catalyst ink, the current is 10x higher and you do not see the feature at -0.4V and you see big double layer effect which is normal.

It can be still also some pollutant. If you purged more or by argon and do not submerge the tip much (the meniscus is the best), you can be sure. I found two papers here that can be interesting: Article Electroactivation of Microparticles of Silver on Glassy Carb...

Article Synergy of Cobalt and Silver Microparticles Electrodeposited...

Thanks a lot Roman Fiala . I will try with mentioned precautions.

You are welcome. You can share the results here also If you will have a time...