Water-assisted clean electro-preparation of Co3Fe7 in molten salt: Enhanced ferromagnetic properties and hydrogen evolution rate

A clean and efficient method for synthesizing Co₃Fe₇ intermetallic is reported, based on the water-asisted molten salt electrolysis employing CoFe₂O₄ electrode, which was fabricated through the thermo-mechanochemical treatment of iron and cobalt oxides. The electrolysis is conducted at the cell voltage of 1.5 V, achiving an energy consumption of 1.47 kWh/kg. Upon formation, the synthesized Co3Fe7 serves as an electrode for catalytic hydrogen production, demonstrating a current density of 91.72 mA/cm2. These performances are compared with those of electrolytic Fe (1.49 kWh/kg, 96.45 mA/cm²) and electrolytic Co (1.30 kWh/kg, 40.76 mA/cm²), both prepared under the same electrolysis potential but with different current-time profiles. The electrolytic Co3Fe7 exhibits superior ferromagnetic properties, with saturation magnetization, remanent magnetization and coercivity values of 157.0 emu/g, 4.3 emu/g and 48.9 Oe, respectively, surpassing values reported in the literature for Fe-Co alloys. The findings suggest a sustainable approach for the green synthesis of Co₃Fe₇ with enhanced ferromagnetic properties. Additionally, the electrolytic Fe and Co₃Fe₇ show promise as electrode materials for molten salt hydrogen production.