Electrocatalytic behaviour of Co–Ni–R (R = Rare earth metal) crystalline alloys as electrode materials for hydrogen evolution reaction in alkaline medium

Ternary Co–Ni–R (R ¼ Y, Ce, Pr, and Er) crystalline alloys have been characterized by means of microstructural and electrochemical techniques in view of their possible applications as electrocatalytic materials for hydrogen evolution reaction (HER). The electrochemical efficiency of the electrodes has been studied on the basis of electrochemical data obtained from steady-state polarization and electrochemical impedance spectroscopy (EIS) techniques in 1 M NaOH solution at 298 K. The results were compared with those obtained on a Co–Ni commercial alloy. The microstructural features play a fundamental role in determining the electrocatalytic activity of the investigated alloys. The overall experimental data indicate that alloying Co–Ni with rare earth metals leads to an increase of electrocatalytic activity in hydrogen evolution with respect to the Co–Ni alloy. High catalytic efficiencies were achieved on Co57.5Ni36Y6.5 and Co57Ni35Ce8 electrodes, the latter being the best electrocatalyst for the HER.