Dear colleagues,
I am having some doubts about how to correctly discuss the Tafel slopes. By definition, they show how much it would be necessary to increase the overpotential to increase the reaction rate by a factor 10. As a consequence, a high Tafel slope indicates that a high amount of energy would be necessary for a reaction to occur, which means a slow reaction rate. This is particularly correct if we see a potentiodynamic polarization curve where E is at y-axis and log(j) at x-axis. Nevertheless, if we put the graphic in the most correct form, i.e., E at x-axis and log(j) at y-axis, this does not work, since a high Tafel slope would indicate that a little voltage difference would imply in high current density variation (i.e., a "faster" rate). So, my question is, what is the correct way to interpret the Tafel slopes?
Thank you all in advance.
Carlos, the link is - from Macias Sensors. Their guide named, "The Tafel Equation: A guide to Electrochemical Kinetics". ------ it should give you the info you need. Its in english - but its available in other languages and the link might automatically give you the guide in you language.
https://maciassensors.com/the-tafel-equation/#:~:text=The%20slope%20of%20the%20represented,slower%20the%20reaction%20rate%20is.
Dear Carlos ,
as I wrote in another similar question, I suggest you to have a look at the following, interesting documents:
-Tafel Slope basics by PerfectLight
Available at: https://www.perfectlight.com.cn/technology/detail-53.html
-Application Note - Getting Started with Electrochemical Corrosion Measurement by Gamry Instruments
Available at: https://www.gamry.com/assets/Application-Notes/Getting-Started-with-Electrochemical-Corrosion-Measurement.pdf
-Tafel Plot and Evans Diagram by Palmsens
Available at: https://www.palmsens.com/knowledgebase-article/tafel-plot-and-evans-diagram/
Enjoy reading and my best regards, Pierluigi Traverso.
Dear Carlos
I recommend to take a look at Uhlig's corrosion book or handbook. As you may know, there is a narrow +-200 mv range. And you can consider two crossed line in that potential range. Also Fontana in his book comprehensively described that.
best luck,