What is the importance of three electrodes system in the electrodeposition of nanostructures on copper substrates? Why Pt electrode should be used as the counter electrodes in the coating procedure?
Reference electrode allows you to measure the potential of working electrode with out passing current through it
and counter (auxiliary) electrode allows to pass current.
This is not possible in a two electrode system although you can get crude values by using certain types of electrodes which can act simultaneously as working and reference electrode