Electrocatalytic properties of Fe-R (R = rare earth metal) crystalline alloys as hydrogen electrodes in alkaline water electrolysis

摘要

The electrocatalytic properties of some Fe-R crystalline alloys, Fe_(90)Ce_(10), Fe_(90)Sm_(10), Fe_(90)Y_(10) and Fe_(90)MM_(10) (MM = mischmetal), were studied for the hydrogen evolution reaction (HER) in 1 M NaOH solution at 298 K. The microstructure of the electrodes was examined by optical microscopy, scanning electron microscopy (SEM) coupled with electron probe microanalysis and X-ray diffraction (XRD) measurements. The performances towards the HER were investigated by dc polarization and ac impedance techniques. The results were compared with the G14 (Fe_(60)Co_(20)B_(10)Si_(10)) amorphous alloy, which is a good electrocatalyst material for the HER. The steady-state polarization curves and electrochemical impedance spectroscopy data showed that high catalytic efficiencies for the HER were achieved on the Fe_(90)Ce_(10) and Fe_(90)MM_(10) electrodes, the latter being a better catalyst as compared with the G14 alloy. Based on the Brewer-Engel valence bond theory, the improvement of the electrocatalytic performances of the Fe_(90)Ce_(10) and Fe_(90)MM_(10) electrodes as compared with the Fe_(90)Y_(10) and Fe_(90)Sm_(10) ones was attributed to synergetic composition effects of the alloys.