doiSerbia

Thermodynamic and kinetic behavior of hydrogen electrode in a solution of O. 5 M KClO4 in dimethyl sulphoxide

Vojinović V. (Faculty of Metallurgy and Technology, 81000 Podgorica)
Mentus Slavko V. (Faculty of Metallurgy and Technology, 81000 Podgorica)
Komnenić V. (Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12, 11000 Belgrade, Serbia and Montenegro)

The hydrogen electrode on an interface platinum/dimethyl sulphoxide + 0.5 M KClO4 solution was examined from both the thermodynamic and kinetic aspect using HCl as a proton source. The equilibrium potential was shown to obey a Nernstian dependence on concentration. The voltammograms recorded using a rotating platinum disc electrode evidenced that the cathodic evolution of hydrogen proceeds under mixed, activation–diffusion control. The diffusion coefficient of the proton was determined to amount to 4.5x10-6 cm2s-1. In the region of activation control, a Tafel slope of about 0.110 V dec-1 was estimated, which indicates that the Volmer reaction is the rate determining step.

Keywords: dimethyl sulphoxide, equilibrium potential, hydrogen electrode, hydrogen evolution, rotating disc.