Highly efficient hydrogen evolution reaction performance and long-term stability of spherical Ni100−xFex alloy grown directly on a carbon paper electrode

Abstract

Ni100−xFex alloy catalysts are prepared as an alternative to Pt-based catalysts for the hydrogen evolution reaction (HER) in water electrolysis. For optimum bonding and adhesion stability between a carbon paper (CP) electrode and Ni100−xFex alloy particles, the latter (obtained by varying the Ni/Fe ratio) is directly grown onto the CP electrode hydrothermally. The shape, crystallinity, and electrochemical properties of the alloy particles were analyzed using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and linear sweep voltammetry (LSV). Raman spectroscopy identifies that very few crystal defects are generated in the Ni100−xFex alloy catalyst during the HER, resulting in a significant improvement in the alloy's electrocatalytic performance. The XPS alloy catalyst profiles before and after the HER reveal water is easily adsorbed on the Fe2+ component, and more H2 is generated on the Ni0 component. The optimum Ni90Fe10/CP catalyst electrode exhibits an overpotential of − 0.244 V (η = 246 mV) and a Tafel slope of 95.4 mV dec−1 at 100 mA cm−2 in a 1.0 M KOH electrolyte. Moreover, the electrode shows a Faradaic efficiency of 97.07% and excellent catalytic activity over 10 days and after 3000 LSV cycles.