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Electrocatalytic behaviour of the Co_33Zr_67 amorphous alloy for the hydrogen evolution

The Co-Zr metallic glasses are binary alloys of early-late transition metals with well-defined electronic structure, physico-chemical and structural properties. In previous studies, the influence of hydrogen doping on microhardness, magnetic and electron transport properties of Co-Zr glasses was investigated. In this paper, we report the results regarding the hydrogen evolution reaction (h.e.r.) on Co_33Zr_67 amorphous alloy electrode as well as on spectroscopically pure polycrystalline cobalt electrode, in order to characterise alloy electrocatalytic activity, efficiency and stability. Surface activation treatment was performed by chemical etching. The Co-rich alloy surface shows very high electrocatalytic activity for the h.e.r. All measurements were performed in oxygen free 1 M NaOH at 298 K. Ribbons of Co_33Zr_67 metallic glass were prepared by rapid solidification of the melt on a single-roll spinning copper wheel in an argon atmosphere. The electrocatalytic efficiency was evaluated on the basis of electro-chemical data obtained from cyclic voltammetry, cathodic pola-risation curves and impedance spectroscopy measurements. The activity of the as quenched Co_33Zr_67 amorphous alloy is rather poor compared to that of poly-crystalline cobalt. Chemical pre-treatment in 1 M HF acid for 60 s significantly enhanced the electro-catalytic activity of the alloy with an increase of j_o by several orders of magnitude. This was attributed to the removal of a thin ZrO_2 oxide film and an enrich-ment of the electrode surface with cobalt.

Co; Zr; Co-Zr alloys; metallic glasses; electrocatalysis; hydrogen evolution

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