I need to convert CV results into Tafel plots. Kindly suggest me the method
For Tafel plot you need a polarisation curve ( a linear sweep voltammetry at low rate), Your CV are obtained at a much higher scanning rate. You may isolated in the data table a linear scan , but you can't change the scanning speed.
My suggestion is to record a dedicated linear sweep voltammetry curve at low scan rate (0.5-2.0 mV/s) before processing data for Tafel plot.
Many Thanks Sir, I will try this but once I have LSV curve then what should I do? I mean what will be my point of interest to convert or obtain a Tafel plot from linear voltametry curve
Following Mr. Cornel Radu's answer, I would suggest that once you get an LSV curve, try to find the kinetics-controlled region and convert the curve in this region based on the Tafel equation: E= a+b*lg(j), which shows a linear relationship between lg(j) and E. Sometimes it is fine to use apparent current density (j) to plot Tafel curve, but in some cases, kinetic current density (jK) is recommended to better reflect the kinetic behavior. I hope this is helpful. Good luck!
1. First read OCP. Then start LSV at (OCP - 300) mV. End scanning at (OCP+200 mV). It is critical for your LSV to pass through i=0.
2. If your software is not able to produce a Tafel plot, then transfer data (i and E) in a Excel/Origin file.
3. In a Excel file convert i to |i| (I recommend to have it in A/cm2) using function ABS (absolute value). Then calculate log|i| . Then plot log |i| vs. E. You have a Tafel plot.
4. Read a good tutorial about Tafel plot. Find two linear segments at 50...150 mV left and right vs Ecorr (in the original curve i vs E , Ecorr is E where i=0). At the intersection of the two lines , read log|i| as log|icorr|. Calculate icorr = 10log|icorr|. Use Faraday's law to calculate corrosion rate.
Many Thanks for your help.
I am using Gamry 600 and software is Echem analyst. I get my data in current density (V vs A/cm2 ). I can get the data in excel file and separate forward and reverse scans. After that can I simply convert A/cm2 in Log (current density) by applying log in excel. Then just draw a graph between Log (current density) and Voltage (V)?
Be sure that all current density values are converted to positive values, before calculating LOG . Use ABS function for that.
Use data from LSV, not CV.
Thank you sir for you kind and prompt responses. Can you also explain why LSV data should be used instead of CV?
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