The potential your option has to be within the range of a faradic capacitance to take place. You can find the potential from your CV results.
Impedance must be measured either at a constant potential or at a constant (or zero) current at which the ac perturbations are superimposed. See my book for details.
i measured the impedance at constant potentials...cathodic and anodic ones w.r.t. OCP...and the behavior of impedance didnt change...what does this mean?? i want a paper that explain the effect of different bias potential on impedance behavior
What is the aim of you experiment? To evaluate the conductivity of your material? To use is as analytical technique?
Andrzel Lasia, your book title please
prof. Antonio Maximiano Fernandes To check the electrochemical behavouir of my material. So i did the impedance at different potential
Title of the book is A. Lasia, Electrochemical Impedance Spectroscopy and its Applications, book, Springer, 2014
Nobody can help you without knowing the details: what is your electrode, what is yporelectrolyte, what is the polarization curve, what are the potentials at which impedance was measured, what are the complex plane and Bode plots, are the impedance results stationary (and K-K compliant)?
my electrode is superconductor and the electrolyte is NaCl and here is the nyquist plot
What are your Bode plots? Complex plane plots cannot give the info about changing capacitance. Anyway, they look different to me. Did you try to model your spectra? If you repeat your measurements are the Bode phase angle plots the same?
What is the chemical nature of your "superconductor" (ambient temperature superconductor!???). What is your polarization curve? What is the surface composition (with respect to the bulk)? Your electrode must be well characterized microscopically, chemically, and electrochemically. Impedance measurement should be the last step of your study.
Your electrode must be performedl electrochemical characterization, surface, chemical and structural characterization, and changing discharging capacitance measurement.