Electroactivity of Ni-Fe cathodes in alkaline water electrolysis and effect of corrosion

- Activity of Ni-Fe cathodes toward HER increased with the increasing Fe content up to about 90 wt.%.
- Alloys with high Fe contents underwent pitting corrosion during hydrogen evolution.
- Cathodic reduction of corrosion products caused temporary activation of cathodes.
- Activation was explained by the formation of intermediates of freshly electrodeposited metal-adsorbed hydroxides.

Alloys of Ni with 10-99 wt.% Fe were examined in 25 wt.% KOH at 80 °C. Electroactivity of the alloys toward HER increased with the increasing content of Fe up to about 90 wt.%, however also increased tendency to pitting corrosion during cathodic polarization. After anodic polarization or corrosion at OCP, cathodic curves of high-Fe materials exhibited a peak which was followed by significant current rise. The peak was ascribed to the reduction of oxide products to metals. It was suggested that the current rise was associated with the formation of active intermediates of freshly-electrodeposited metal-adsorbed hydroxides.