I am interested in measuring the potential between the working electrode (WE) and the counter electrode (CE) in a 3-electrode system. I used a Bio-logic potentiostat, which is capable of measuring the potential of WE and CE simultaneously. Hence, it can provide the difference between the potential of WE and CE (Vwe-Vce). Is this value (Vwe-Vce) the exact potential between the WE and CE? Do I need to add the open circuit potential (OCV) to this value (Vwe-Vce) to get the exact value? I am asking this because, I did a linear sweep voltammetry (LSV) in both the 3-electrode and 2 electrode configuration. The plot of current vs Vwe-Vce (3-electrode value) and current vs V(2-electrode) have a difference of about 0.3V in the current onset potential.
Typically the 3 electrode setup is more reliable for measuring the potential difference, as long as the reference electrode to which you compare is stable over time. The counter electrode is meant to supply the current to the system, thus so the potential will not remain the same over your linear scan. That might explain the difference between your 3 electrode and 2 electrode measurements. Try hooking up the counter electrode as working and reference as reference. Any measurement other than 0V should account for this discrepancy.
Dear Ganesan
You would not expect the answer to be the same. In one case the potentiostat is controlling the voltage difference with respect to a reference electrode and counter electrode can go to any value (within the compliance limit) to deliver the required current. In the 2 electrode case the voltage difference is fixed by what you asked for in your experimental setup.
Best regards
Dave
- Badges
- Science topic