HYDROGEN EVOLUTION REACTION ON THE NICKEL ELECTRODE IN MOLTEN ORGANICSALT

Hydrogen evolution reaction (HER) has been studied in pure molten trie thylammonium fluoroborate (TEABF4) on a polycrystalline nickel cathode using galwanostatic, ac impedance, relaxation and open circuit potent ial decay techniques. Two overpotential regions with different mechani sms of the HER have been found. The kinetic parameters of the HER have been determined in the temperature range 403-443 K. The Heyrovsky dis charge reaction is the rate determining step in lower temperatures, wh ereas in higher temperatures both Volmer and Heyrovsky are reactions r ates similar. A very small double layer capacitance and high electroly te resistance is observed. This suggests the formation of some chemica l species on the surface of Ni electrode.