Characterization of Fe–Zn–R (R = rare earth metal) crystalline alloys as electrocatalysts for hydrogen evolution

The electrocatalytic properties of some Fe–Zn–R crystalline alloys (R=rareR=rare earth metals), Fe80Zn10La10Fe80Zn10La10, Fe80Zn10Y10Fe80Zn10Y10, Fe80Zn10Gd10Fe80Zn10Gd10 and Fe80Zn10MM10Fe80Zn10MM10 (MM=mischmetalMM=mischmetal: 50.2% Ce, 26.3% La, 17.5% Nd, 6.0% Pr, at%), were investigated for the hydrogen evolution reaction (HER) in 1 M NaOH solution at 298 K. The microstructure of the electrodes was examined by optical microscopy and scanning electron microscopy coupled with electron probe microanalysis; X-ray diffraction measurements were also performed. The performances towards the HER were investigated by dc polarization and ac   impedance techniques and the results were compared with those obtained on polycrystalline nickel. The microstructural features play an important role in determining the electrocatalytic activity of the investigated alloys. The overall experimental data indicate that interesting electrocatalytic performances are displayed by the Fe80Zn10Gd10Fe80Zn10Gd10 electrode, which exhibits the highest activity towards the HER.