I am doing work on non-precious metal catalyst for ORR. All the times, I get narrow peak using CV while a broader peak using LSV for the same catalyst (as shown in the attached figure) at same scan rate, quiet time and sensitivity. I think I should get same peak potentials in CV and LSV for the same catalyst. So, why I am getting this difference in peak potentials?
If you record LSV under solution stirring conditions, LSV and CV MUST be different
Verify your rotating electrode: apparently it is not stationary at nominal 0 rpm .
For the main problem I agree with Yurii V Geletii.
As a good practice rule, I suggest to not use any rotation speed below 1000 rpm. To improve your results, increase the rotation speed and ignore any record below 1000 rpm.
Thanks to all for the answers.
I am still confused why there is so much difference in the peak potentials of CV and LSVs as most of the authors presented their peak potentials in LSVs closer to their CV (not exactly) with an increase in current with the rotations. However everytime I get a very large difference (like 0.2V). Can you suggest where am I lacking? Can I do something to minimize the peak potentials of LSV at different rotations so that they may have closer potentials to the CV?
Secondly, I believe that the half wave potential is the average of anodic and cathodic peak potentials through CV but authors mention half wave potential through LSVs which I assume they are mentioning as the average of onset and peak potential (which should be cathodic half peak potential instead of half wave potential). Please suggest me if we can consider the half peak potential and half wave potential same thing?
Tran Thanh-Nhan, I am unable to understand how capacitive current can narrow the peak in CV.
Muhammad Shoaib The science is all about details. You will never get a right answer without providing a full description of your experiments.
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