INSITU ACTIVATION OF CATHODES DURING ALKALINE WATER ELECTROLYSIS BY DISSOLVED IRON AND MOLYBDENUM SPECIES

In situ activation on polished pure Co, Fe, Ni and Pt cathodes by the dissolution of molybdenum in 30 wt% KOH at 70-degrees-C was investigated at 100 mA cm-2. The effect of adding molybdate to the electrolyte to reactivate hydrogen discharge depends on the concentration of dissolved iron. The deposition of Mo on the substrate takes place only in the presence of this metallic impurity. The best improvement of the hydrogen evolution reaction is reported when iron alone is dissolved in the electrolyte. The nature of the changes occurring on the cathode surfaces during hydrogen evolution was demonstrated by scanning electron microscopy and X-ray microanalysis.