I work on inhibition of copper corrosion in HCl and NaCl medium. I use a three electrodes system: SCE as reference, Pt as counter electrode and copper that I embedded in resin to leave 1Cm2 area as working electrode and soldered with a metallic wire for contact with potentiostat (Biologic instrument). Concerning the surface preparation of my working electrode, I use abrasive paper ( from Number 1 to number 6) followed by distilled water rinsing.
I conducted many impedance measurements between 100KHz and 100mHz, 10mV amplitude in NaCl 0.5M BLANK. Unfortunately I only recorded undescribed nyquist curves (scattered discontinuous point).
As far as the electrodes are concerned, the continuity of my working electrode is OK, the reference electrode displayed OCP values that correspond with existing data in the litterature (around -0.2V in NaCl 0.5M). Also, I always immerse the three electrodes in the same electrolyte in contrast to some experimental procedures describing a separate cell for reference electrode linked to the electrolyte using a salt bridge.
Is there any parameter or any experimental condition I need to adjust to get good impedance data?
Hi there,
it is depdent on the engout time allows in ocp and avoid the drifting sample through the measurement test as well conect the senser of reference electode
Regards,
Dear Olubunmi Kolawole,
in your EIS, for corrosion studies, you might have accessible one of the : Potentiostatic / Galvanostatic modes (Biologic instrument).
1) You say that you, already, implemented the Potentiostatic[1] mode having extended EIS (PEIS) impedance measurements (potentiostat - Biologic instrument). However, you might acquire (more) reliable measurements (in PEIS), if you could collect faster[2] spectra. This is an easy option, to collect more stable, and advantageous Nyquist curves, for "comme il faut" fitting in the PEIS, e.g. virtually non-scattered and "discontinuous network" of points.
2) Another, more advantageous, choice might be, if you could implement a Galvanostatic mode for more stable EIS impedance measurements during the interval of the Cu-corrosion. Here, in corrosion, the OCP might be (very) unstable during a common (P)EIS measurement. However, the GEIS (Galvanostatic mode EIS) is very stable[3], since, during the GEIS is essentially "OCP free".
So, in your case, for Copper corrosion studies, I would propose the 2nd choice (GEIS) for a set of EIS measurements (for the time being of the Cu-corrosion[4]).
1. Your description : "I conducted many impedance measurements between 100KHz and 100mHz, 10mV amplitude in NaCl 0.5M BLANK. Unfortunately I only recorded undescribed nyquist curves (scattered discontinuous point)."
2. A small FHL (High-Low frequency) range, between (100KHz, 1Hz), and much less than (T
thank you so much for your contribution dear Ioannis Samaras, Pramod K Kalambate, Qhatan Adnan Yousif. I will implement it as you advice.
Dear Kolawole,
There could be number of reasons for data scattering, I may diagnose the issue in your case but for this i would need some more information about your system, if possible could you please share the following information
1. OCP trend
2. Linear polarization scan within +/- 10 mV vs OCP potential range
3. Inhibitor type (means, oxidizing, reducing, etc.), no need to disclose composition
4. Experimental setup and cell design, one picture is enough
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