Repeatable and renewable synthesis of nickel–iron nitrate hydroxide needle-like arrays for water electrolysis†

A sustainable approach utilizing a low-temperature molten salt strategy is employed in this study to fabricate homogeneous and dense NiFe nitrate hydroxide needle-like arrays on a NiFe foam substrate. The electrode also achieves an ultra-low voltage of 1.77 V at 100 mA cm⁻² and maintains stability for more than 120 h at a current density of 100 mA cm⁻², showing excellent overall water splitting (OWS) performance and stability. Notably, the molten salt strategy enables the synthesis of electrodes at a reaction temperature as low as 125 °C. Additionally, the molten salt precursor is repeatable and renewable, thus preventing waste and presenting vast potential for application.