Formation of nickel hydrides by hydrogen evolution in alkaline media

The feasibility of obtaining Ni hydride through electrolytic reduction of aqueous 0.6 M K2CO3 at Ni electrodes of different types (solid Ni, Ni-fiber composite and sintered Ni) was investigated. It was found that potentiostatic electrolyses at the beginning of the hydrogen evolution reaction (her) lead to the formation of several hydrogenated species of Ni, which generally become degraded when more negative potentials are applied. The species oxidized reversibly with the her was identified as the ?-Ni hydride phase, whereas the nature of the Ni hydrides oxidized at more positive potentials could not be definitely established. The interaction of Ni samples on open circuit with H2 dissolved in the electrolyte was found to form the same Ni hydride species as that achieved after electrolysis.