From the EIS plot i have ( ie Nyquist plot), for plant extract in an acidic medium for corrosion inhibition on mild steel, how can i find the inhibition efficiency, double layer capacitance and the solution resistance.
Here is a paper on Nyquist plot that was really helpful to me (Sensors 2021, 21(19), 6578; https://doi.org/10.3390/s21196578).
It explains most of what you asked for (except inhibition efficiency).
Thank you so much sir, most grateful. I will get back to you sir.
Dear Ibejekwe Sunday John ,
first of all, you should use orthonormal scale, otherwise you might make mistakes about the components to be chosen in your electrical equivalent circuit. More details are here: https://www.biologic.net/topics/nyquist-plots-why-use-the-orthonormal-scale/
Secondly, to find the double layer capacitance,if you are sure that you have R/C an not R/Q (Q is a Constant Phase Element), you can simply the frequency at the apex of the semi-circle. This frequency = 1/(2Pi R C) where R is the diameter of the semi-circle. I hope this can help you. best regards, Nicolas
Nicolas Murer , thanks so much but may I ask the formula given by you is it same with -Z(Fmax) = 1/(2Pi)(Rct)(Cdl).
Dear Ibejekwe Sunday John
No it is not -Z(Fmax). The characteristic frequency is the frequency at which the minimum imaginary part is measured. See the attached image.
Best regards,
Nicolas
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