Currently, I am performing electrochemical analysis on screen sprinted gold electrodes and extracting Impedance and CV curves. I am new to this field. From the literature, I read that charge transfer resistance is a combined effect of resistance and capacitance. I need only the resistance component. Is there a way to extract it?
In impedance, the ohmic resistance is obtained by the intercept of the spectra with the x-axis at high frequency. If your spectra doesn't cross the x-axis, you have to increase the upper limit of the frequency range.
Written like this, the sentence is wrong: "charge transfer resistance is a combined effect of resistance and capacitance". At least, it depends on what you are talking about with resistance and charge transfer resistance....
If you have no mass transfer limitation and if the kinetics of one electrode is so high that it is not visible your spectra, then you should have a spectra looking as a semi-circle (a so called Randles circuit). In this case, the intercept of the semi-circle at high frequency gives you the ohmic resistance while the diameter of the semi-circle gives you the charge transfer resistance.
It sounds like you want a single value to assign to resistance of the electrode, to simplify your analysis. If this is your intent, then my answer is no: that would oversimplify the system, and you would be ignoring important changes at the interface if you took that approach.
That said, there is a way used by most experimentalists to avoid the complexity of impedance and the likely confounders such as side reaction products with your electrolyte. I don't recommend this, since it often produces poor quality research. However, if someone is pressuring you to generate results that match those in other publications, the solution is to fit your EIS data to an equivalent circuit - R(RC) is popular but R(C[RW]) is more likely to match your pristine gold electrode - and ignore all data except the value fitted by your software to the last resistor, which is often called charge transfer resistance. This means your research will be dependent on the algorithm used by one proprietary fitting program, you won't know if the circuit is an appropriate one for your system, and you'll be hiding behind the poor practice repeated by others. Best of luck.
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