Electrocatalytic water splitting consists of two half-cell reactions, oxygen evolution reaction (OER) at anode and hydrogen evolution reaction (HER) at anode. But both the OER and HER cannot occurs at their standard electrode potential (0 V vs RHE for HER and 1.23 V vs RHE for OER), there will be always a need of additional potential compared the theoretical potential and this additional potential is called as overpotential. The requirement of large overpotentials and slow kinetics for both HER and OER inhibit the practical application of overall water splitting.5 On the other hand, compared to HER, OER is kinetically very sluggish because it is a four-electron transfer process whereas HER is facile with only two electron transfer process.

Thank you, Saddam Sk. But this is not the answer to my question. Your description relates to the generalities of LSV.

" Usually for OER, for example, a potential range between -0.1 to 1 is chosen. " Who chooses this range?

" Why take a CV in an area where the reaction does not begin? " This is the answer for your question!

Yurii V Geletii Thank you very much for your answer and guidance. The approximate potential range of -0.1 to 1 V, can be seen in most papers. But if I do not misunderstand your answer, selecting this area of potential is only to pre-activation the electrocatalyst surface, and after this step, it does not matter if we intend to take the HER test or the ORE. it's true?

" The approximate potential range of -0.1 to 1 V, can be seen in most papers. " It's not true for the top papers. For the OER/HER the most important is the highest/lowest potential achievable in the system. You have to determine it experimentally. Commonly, this is called an electrochemical window. Saddam Sk explained how to do this. I don't know what is " pre-activation the electrocatalyst surface"

Yurii V Geletii The attached paper is an example, you can see the CV curves in it. Of course, the potential range I mentioned was relative to Ag/AgCl which is approximately 0.1 to 1.2 V relative to the RHE. The explanation of Saddam Sk is rudimentary, and this explanation is explained at the beginning of every electrochemical book, and of course, I am not looking for such an answer here.

If you want a professional answer, your question should be professionally formulated.

" the potential range I mentioned was relative to Ag/AgCl which is approximately 1 to 1.4 V relative to the RHE. " You will find "at the beginning of every electrochemical book" that this is wrong.

" Why take a CV in an area where the reaction does not begin? " Water oxidation is 4-electron process and includes at least four separate 1-electron reactions, which might be seen at lower potentials.

Yurii V Geletii " Why take a CV in an area where the reaction does not begin? " This is the answer to your question!

Getting a CV voltammogram in a potential range that includes the potential of only one step of the reaction! What is the reason?

" Getting a CV voltammogram in a potential range that includes the potential of only one step of the reaction! " I did no say that!!!!!!!!!!!!!!!!!!

Yurii V Geletii "Water oxidation is 4-electron process and includes at least four separate 1-electron reactions, which might be seen at lower potentials." But theoretical voltage of OER is 1.23 V. The experimental potential is any value greater than 1.23 V!

This is not an educational forum. I can't spend more time to explain you basics of water oxidation/splitting thermodynamics. " But theoretical voltage of OER is 1.23 V" Wrong! The correct one is E = 1.23 -0.06*pH

Yurii V Geletii You said

" Usually for OER, for example, a potential range between -0.1 to 1 is chosen. " Who chooses this range?

" The approximate potential range of -0.1 to 1 V, can be seen in most papers. " It's not true for the top papers.

while there are a lot of top papers that confirm my point. So you need to increase your studies and accuracy in this field and then guide others!!!