Surface and electrochemical characterization of Ni-Zr intermetallic compounds

In this paper the Ni-Zr system has been considered with the aim of investig ating the role of composition and structure of an early-late transition met als system on the electrocatalytic activity, for the hydrogen evolution rea ction. As a matter of fact, pure Ni and Zr show low activity, while their i ntermetallic compounds generate a higher catalytic efficiency. Five alloys, with increasing Ni content starting from Ni33Zr67 UP to Ni75Zr25, have bee n prepared and characterized. The alloy of composition (Ni0.55Mn0.30 V0.10C o0.05)(2.1) Zr has also been considered, in order to investigate the cataly tic efficiency related to a Laves structure. The thickness and composition of the surface oxides have been investigated and their effect on reducing t he catalytic efficiency of the as-prepared alloys has been discussed. The a ctivity of the samples submitted to a surface activation treatment with hyd rofluoric acid, that removes the oxide layer and allows to evidence the pro perties of the compounds, has been observed to increase significantly. The trend of the electrocatalytic efficiency with the composition of the alloys is discussed considering a synergetic effect between Ni and Zr. The Laves phase appears slightly more active than the binary intermetallic compound. (C) 2000 Elsevier Science Ltd. All rights reserved.