Dear Yurii V Geletii, Thank you so much for your kind reply to my question! Actually I have been doing this work for more than a month yet I need certain help from the experts and experienced research professionals. So that I asked this one, If you don't wanna help me, fine! But please do not disgrace me sir!
I did not intend to disgrace you. It's excellent if you did your part of job. That's what I advised you. What you need is to hear an opinion of experts about your own answer to your question. You may need to attach the file with your own opinion and slightly reformulate the question. Otherwise your question does not sound good.
I need to do the same job as you have done to answer you. Keep in mind how they define the overpotential and how they measured it. The current density is a separate story. It may depend on the cell design. IrO2 catalyst might be different. In summary, you can't compare the different systems using a single parameter, the overpotential.
I would advise you to write a short summary of your literature search with a critical analysis of data. It would be very helpful to organize your thoughts. I would be willing to comment this summary.