Can someone please explain to me the concept of overpotential? And also what does it mean in relation with electrocatalysts? Thx

Can someone please explain to me the concept of overpotential? And also what does it mean in relation with electrocatalysts? Thx

 

Does it help?

https://en.wikipedia.org/wiki/Overpotential

https://en.wikipedia.org/wiki/Electrocatalyst

I've tried reading it, but apparently I'm not smart enough. Thats why I asked here

You calculate the cell emf. I am using an example from https://www.chem.wisc.edu/deptfiles/genchem/netorial/rottosen/tutorial/modules/electrochemistry/05potential/18_52.htm

 

oxidation Zn(s)Zn²⁺(aq) + 2e^–E° = 0.763 V

reduction 2 [ 1 e^– + Ag⁺(aq) Ag (s) ] E° = 0.337 V

sum

net Zn(s) + 2 Ag⁺(aq) 2 Ag(s) + Zn²⁺(aq) E° = 1.100 V

 

Then you calculate the emf using a multi-meter. You would expect the emf to be the same as the theoretical value obtained from the chemical equation. However it turns out to be different and this difference is called the over-potential. So basically with over-potential they are talking about rates of reaction in over-complicated technobabble. So when talking about electrocatalysts are you need to remember what catalysts are. They speed up the rate of a reaction/control the reaction in some way. Also there are reasons for not adding catalysts which would slow down the reaction increasing battery life.

Edited March 15, 20169 yr by fiveworlds

Thanks, but what would be some of the reasons that the experimental would be different?

The same as for changes in reaction rate. Temperature for instance plays a major factor. Batteries that work well in the uk won't work well in the Sahara desert the battery life is shorter because the reaction occurs faster.

The same as for changes in reaction rate. Temperature for instance plays a major factor. Batteries that work well in the uk won't work well in the Sahara desert the battery life is shorter because the reaction occurs faster.

Great, thanks!