Hello,

Indeed the OCV (open circuit voltage) changes when you introduce your sample in your electrolyte. It can increase and/or decrease and finally it should stabilize. To do e.g. a corrosion measurement, you have to wait until the potential is stable, in this case your system is in steady state and you can do your measurement.

for your case, OCV is plus or minus, the meaningful is depending of its variation.

What is your system : electrodes and electroyte? Show us the curve you obtain, we could give your more information I think.

Best Regards

Thomas

Hi,

Like Thomas said, it is very important to know how much does the OCP vary. A variation of the OCP in the range of +/-25 mV or maybe more, is normal in some cases, until the system gets stable. Moreover, it depends very much on the working electrode and on the solution you are using. If the electrode is not chemically stable in the electrolyte, the OCP will change, consequently.

Normally, the OCP is the potential difference between the working electrode and the reference, when no external current flows through the circuit.

More information would be useful.

What is your cell (electrolyte, and WE, RE electrodes) ?

I appreciate your replies,

I am using Boron-doped Diamond electrode(wk), Hg/HgSO4 electrode (Rf) and 0.1M KNO3 (electrolyte).

Maybe, you, already, know, whether your doping of Boron results in some extra boron (2D-segregation[1] or/and 3D-precipitation) rich phases along with Boron-doped Diamond electrode (WE).

If you do not know, earlier, then such an Electrochemical Potential Noise (EPN)[2,3], that is depending on electrolyte's concentration (0.1M KNO3), might be an initial hint to check deeper for possible extra boron phases e.g. a lesser Boron doping. Also, a subordinate (doped) B:Diamond increases the resistance of your (WE) electrode and the EPN - amplitude[4,5].

1. Direct imaging of boron segregation at dislocations in B:diamond heteroepitaxial films https://pubs.rsc.org/en/content/articlepdf/2016/nr/c5nr07535a

2. Electrochemical Potential Noise Analysis of 304 Stainless Steel Weld Zone Exposed to Alkaline Solutions by Different Parameters https://www.scientific.net/AMM.331.469

3 Simplified electrochemical potential noise method to predict corrosion and corrosion rate https://www.sciencedirect.com/science/article/abs/pii/S0950423017301821

4 You say that: Open Circuit Voltage (OCV over time) ... are plus or minus...

5 OCP in very complex or "multiphase" electrodes (corrosion, etc.) has a "forbidden" (hidden, important, "noisy") parameter: the kinetics aspect. See my note in: https://www.researchgate.net/post/What_is_the_importance_of_the_Open-Circuit_Potential_OCP_in_an_electrochemical_cell