[aeacfm]

i searched the web for the above mentioned subject , all what i knew that the hydrogen over potential is specific for every metal or for every type of electrode ...
so if i need carbon cathode of high hydrogen overpotential , is there any body know any data or the parameters (like voltage , current density) about that ?

any reply i appreciate
 

[FreeTheBee]

You could look into boron doped diamond electrodes. They have a large overpotential for both oxygen and hydrogen evolution.

[aeacfm]

thanks a lot
but unfortunately i specifically need carbon electrode - it is so important to me -

[FreeTheBee]

Diamond kinda is carbon.
Another option could be glassy carbon. Neither are very cheap options though.

[aeacfm]

thanks alot

this  is a non-graphitizing carbon which combines glassy and ceramic properties with those of graphite   as i find in wiki

what i want is also specifically graphite cathode
iam sorry i didnt know there is such types of carbon electrode
thanks again

[FreeTheBee]

Graphite itself also has an overpotential  for hydrogen evolution but not as much as the other two. If you search overpotential in wikipedia you'll find a small table. I don't know what your application is, but perhaps you could just try a graphite rod or even carbon paste.