Hi Shoaib,

In case of CV, the peak ORR shows a shape peak due to it is included both ORR current and capacitive current. In case of LSV, it may mainly current from ORR (still exitstence a bit of capacitive current), so then LSV curves show lower E1/2 compared to that of CV. The LSV from -0.3 ~ -0.6 V (mass transfer region) at low rotation rate of 0 - 400 rpm, they show broad peaks corresponding to limited mass transfer process, in which O2 gas is difficult to aproach the active species due to your deposited catalyst layer on glassy carbon electrode may too thick or your active material may too much porosity. Other LSV from 625 - 1600 rpm look seem nice curves because the mass transfer was improved by electrode rotation.

With me, you should examine LSV curves more than 500 rpm (e.g. 500, 800, 1100, 1400, 1600 and 2500 rpm). If you need further detail, you can get a reference from my previous paper.

https://pubs.rsc.org/en/content/articlehtml/2018/cy/c8cy01140k

Hope it can help.

Hi Shoaib,

In case of CV, the peak ORR shows a shape peak due to it is included both ORR current and capacitive current. In case of LSV, it may mainly current from ORR (still exitstence a bit of capacitive current), so then LSV curves show lower E1/2 compared to that of CV. The LSV from -0.3 ~ -0.6 V (mass transfer region) at low rotation rate of 0 - 400 rpm, they show broad peaks corresponding to limited mass transfer process, in which O2 gas is difficult to aproach the active species due to your deposited catalyst layer on glassy carbon electrode may too thick or your active material may too much porosity. Other LSV from 625 - 1600 rpm look seem nice curves because the mass transfer was improved by electrode rotation.

With me, you should examine LSV curves more than 500 rpm (e.g. 500, 800, 1100, 1400, 1600 and 2500 rpm). If you need further detail, you can get a reference from my previous paper.

https://pubs.rsc.org/en/content/articlehtml/2018/cy/c8cy01140k

Hope it can help.

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.

Potential in range of -0.1~0.2 V has current higher than 0, indicating there is a formation of H2O chemical absorption, -OH, -O- groups onto your catalyst surface due to oxidation process, and then the current is dropped at -0.1 ~ -0.2 V, which is included both current from ORR and reduction of functional oxygenate groups on your catalyst surface.

I'm certainly curious either CV curves or LSV curves were examined first?

Muhammad Shoaib The science is all about details. You will never get a right answer without providing a full description of your experiments.