HYDROGEN EVOLUTION REACTION ON NI-S ELECTRODES IN ALKALINE-SOLUTIONS

The hydrogen evolution reaction mechanism on electrodeposited Ni-S coa tings of low sulphur content was initially studied in alkaline solutio ns through steady-state polarization measurements. Tafel plots were an alysed at several temperatures and varying pH. The results suggested a mechanism involving fast electron transfer followed by a slow electro chemical desorption step. This Volmer Heyrovsky mechanism was fully co nfirmed by impedance spectroscopy measurements through the fit of the results with those derived theoretically for the different mechanisms. The values of the corresponding rate constants were obtained for temp eratures ranging from 0 to 60-degrees-C.