Researchers have used different range of log abs J, depending upon what criteria? I want to calculate tafel slope of my catalyst NiS, what range should i choose ? Here my polarisation curve.
You can't plot Tafel equation. Plot the dependence of over potential versus log10(current density). See what you have and read textbooks to explain your data. If necessary, extend the experimental range of over potentials, read textbooks, and so on.
Hamza Naeem a Tafel curve is a representation of the Log |J| vs. overpotential. The overpotential is equal to the applied potential minus the equilibrium potential. However, you can use applied potential instead of overpotential, depending on what you want to observe. The range that is chosen to calculate parameters such as exchange current and Tafel slope is the linear region immediately surrounding the zone of polarization resistance. A Tafel curve should show a first zone where the potential and current density are independent, then the electrode gradually polarizes and a zone appears where there is a dependence between current density and potential or overpotential. You must perform a regression of the entire linear range of that zone. Normally the potentiostat software allows you to calculate the Tafel slope directly, i.e. they make the fitting. Regards!
@Javier Ernesto Vilaso Cadre the voltage plotted on x-axis is overpotential since equilibrium potential for hydrogen evolution is zero. I am studying hydrogen evolution , so im just trying to understand what is the criteria of selecting the range of Current density from polarisation curve which is then converted to log j. The tafel slope obtained from that particular line gives idea about rate determining step (volmer, heyvrovsky, tafel)
Dear Hamza Naeem , what I wrote is to explain how to build a Tafel plot, because what you show is a polarization curve. I also explain the parts of a basic Tafel plot, because you will understand which regions to use to calculate the Tafel slope, which in some reactions like HER, can be more than one. You should analyze your data as a Tafel plot based on what is described for HER.
Check this:
Article The determination of the HOR/HER reaction mechanism from exp...
and this:
https://essay.utwente.nl/68735/1/Bachelor%20verslag%20Chris%20van%20de%20Goor%20s1251066%20-%20openbaar.pdf
Regards!
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