Ni-base amorphous alloys as electrocatalysts for alkaline water electrolysis

Abstract

The development of efficient and cost effective electrodes for hydrogen generation from water electrolysis and for hydrogen oxidation in power generation from fuel cells is very important in developing the hydrogen economy. This paper focuses on the role of the structure and chemistry of amorphous metal alloys (AMA) on the electrocatalytic activity for the hydrogen evolution reaction (HER) in alkaline water electrolysis. The test AMA electrodes, Ni-base alloys with different metal additive ratios, were prepared by a planar flow casting technique. The electrochemical behaviour of the AMA was investigated in 1 M KOH at 30 °C by cyclic voltammetry and steady-state polarization techniques. The AMA displayed voltammetric responses similar to that of crystalline Ni, however, differences were found in the oxide formation mechanism. The electrocatalytic activities of the AMA were dependent on the AMA composition. The prepared alloys displayed good stability relative to that of crystalline Ni. Even after extensive potential cycling which roughened and attacked the crystalline Ni electrodes, the surfaces of the amorphous alloys remained smooth. As a result of the roughening of the crystalline Ni electrodes, the amorphous alloys appeared to be less active than crystalline Ni for the HER on the basis of geometric surface area.