Amorphous alloys as anodic and cathodic materials for alkaline water electrolysis

The general tendency of operating modern industrial electrolyzers at high current densities has stimulated research on materials with improved catalytic properties for the hydrogen and oxygen evolution reaction in alkaline water electrolyzers. The performances of electrocatalytic materials have usually been improved by increasing the ratio between the real and the apparent surface area. A less common way of improving the electrocatalytic activity is by modifying the microstructure of the alloys. In this paper we describe the electrocatalytic properties of various amorphous alloys. Among those investigated, amorphous Fe-Ni-Si-B exhibit oxygen potential vs Hg/HgO of around 600 mV at 300 mA/cm(2) in 30 wt.% KOH at 60 degrees C. Polycrystalline nickel was less electroactive, indicating that the amorphous state is a better precursor for the formation of an active surface layer. In the alloys tested, metal-metalloid glasses are chemically unstable for high concentrations of iron and the electrode overvoltage decreases with an increase of iron. Consequently, corrosion resistance and electrode performance were found to have opposite dependence on iron concentration. (C) 1997 International Association for Hydrogen Energy.