You have two compartments: anodic and cathodic.In order to measure the electrochemical potential of cathode, you need to measure the voltage between cathode and reference electrode. The same for anode. Thus, you should have 4-electrode system, which has two reference electrodes and two working electrodes. A bi-potentiostat can handle such 4-electrode configuration. E.G, see
Sir, Yurii V Geletii I am highly thankful to you for your prompt response. I have solar panel of 6V in my hand, Now, I dont know how much potential it will give to cathode and how much to anode simultaneously.
Irrespective of its construction a solar cell is a two electrode device. The anode and the cathode. in electrochemical solar cells there is an electrolyte between the cathode and anode. From your question i understood that the photelectrode is the cathode and the Pt electrode is the anode. As a solar cell you need only to measure its terminal performance between the anode and the cathode. That is the I-V characteristics of the solar cell just as the normal solar cell.
In case of investigating the electrodes where one is interested in the I-V of the electrodes, one can use three electrode measurements by inserting a reference electrode in the electrolyte. This may be the standard calomel electrode SCE. Then one can measure the the anode I-V characteristics versus the reference electrode, and can measure also measure the I-V characteristics of the photo-cathode versus the reference electrode. Let us assume that one measured Ia vesrsus Va- Vr and measured Ic versus
Vr- Vc, then for a given Ia = Ic,, V of the solar cell = the summation of the two= Va-Vc.
This may lighten the problem and may resolve some of your query
Based on your original question your device has two compartments with Pt-electrode and electrolyte. Now you are saying: "I have solar panel of 6V in my hand." What kind of the device do you have in your hands? Do you ask about open circuit potentials?
In this link "http://pubs.acs.org/doi/abs/10.1021/acsami.5b04393"
Author has written that "Solar-cellpowered CO2RR was conducted for 12 h to mimic operation during a sunny day (6 h/day, 2 days). The solar cell provided −0.78 ± 0.11 V vs RHE to the cathode and +4.53 ± 0.04 V vs RHE to the Pt anode" I couldnot understood that how he determined that potential??