After three decades of intense development of activated electrode materials for alkaline water electrolysis, a careful revision of the literature shows that innovations are restricted to a small number of new systems (1, 2). Among them, some Ni-based alloys have been successfully tested as efficient cathode materials (3, 4) while the choice of anodes is mainly focused on mixed Ni-Co oxide with a spinel structure (5, 6). Our laboratory has been working in the development of activated materials for water electrolysis for the last 15 years. Initially, research was directed to the preparation of activated Ni alloys to be used as cathodes in the electrolysis cell (7). In this field, two different approaches were followed. Firstly, high area Ni or Ni-Co alloys have been produced by using an electrolytic bath containing Zn~(2+), in order to promote the codeposition of a high-content Zn alloy. These alloys were then avtivated by chemical leaching of the Zn phase thus producing very porous usrfaces (8). Such methodology was further improved by introducing a step of gradual addition of Zn~(2+) into the Ni or Ni-Co bath during deposition. This yields deposits with a multilayer structure that, after activation, presented roughness factors as large as 4x10~3 detelrmined by cyclic voltammetry (9, 10).
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