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 th at potentiostatic electrolyses at the beginning of the hydrogen evolut ion reaction (her) lead to the formation of several hydrogenated speci es of Ni, which generally become degraded when more negative potential s are applied. The species oxidized reversibly with the her was identi fied as the beta-Ni hydride phase, whereas the nature of the Ni hydrid es oxidized at more positive potentials could not be definitely establ ished. The interaction of Ni samples on open circuit with H-2 dissolve d in the electrolyte was found to form the same Ni hydride species as that achieved after electrolysis. (C) 1998 Elsevier Science S.A.