I would like to estimate the ionic conductivity of the protonated membrane(Nafion211) using H2SO4 at 3M for 2 days.
I use EC-lab program, and SP-150, VMP3B-10.
The experiment is simply done by placing the membrane between the two cells and the electrolyte using 1M H2SO4.
Than, I am doing conductivity measurement of using resistance when Impedance is zero(the x-intercept data) in a frequency range of 400kHz to 30Hz.
But I am not sure what is the right figure of graph and How can I setting the program. I want to know I am doing right or I need to correct something.
Basically, you need to measure EIS spectra of your sample and then fit them with appropriate circuit model. BioLogic's software provide the EIS fitting. Please check following papers:
1. http://jes.ecsdl.org/content/143/4/1254.full.pdf+html
2. http://pubs.acs.org/doi/pdf/10.1021/jp409675z
Your impedance data doesnt show any clear plots (like semi-circles or Warburg diffusion etc). rather it has lot of noise points at higher frequency.
So first you optimize the input (amplitude of the sine wave and apply appropriate frequency) then you would get proper data which should be fit with an equivalent circuit available in the machine itself.
You would get R(charge transfer resistance) and C or Q (Capacitance) from the fitted circuit. Apply resistance (R) value in the formula sigma=1/R* L/A where L=distance btw the electrodes and A = total surface area of the electrodes.
Apply resistance (R) value (from the Eq circuit) in the formula, the calculated sigma (in S cm-1) is your Ionic conductivity.
Good luck!
1) Extent your lower frequency range (below 30Hz).
2) Could you show a schematic (or a photo) of your electrical contacts on the membrane ?
It seems your electrical contacts between the connectors and your membrane are not good, hence it shows a lot of noise.. i think you can extend the frequency to 10mHz on lower side..
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