Ultrathin Amorphous Iron-Nickel Boride Nanosheets for Highly Efficient Electrocatalytic Oxygen Production

A cost-effective and efficient electrocatalyst for the oxygen evolution reaction during the electrolysis of water is highly desired. In an effort to develop an economical material for replacing precious-metal-based catalysts, a novel and self-standing amorphous ultrathin nanosheet (NS) of bimetallic iron-nickel boride (Fe-Ni-B NSs) on Ni foam is presented, which displays a better oxygen-evolving activity compared to the precious-metal catalyst RuO₂ . In 1.0 m KOH electrolyte solution, it requires an overpotential of only 237 mV to reach a current density of 10 mA cm^-2 with a small Tafel slope of 38 mV dec^-1 and shows prominent long-term electrochemical stability. A synergistic effect between highly abundant catalytically active sites on the 3D porous substrate improved the electron transport arising from the presence of highly negative boron, and the high conductivity of the substrate results in an outstanding electrocatalytic activity. The advanced catalytic activity, facile electrode fabrication, and low costs make it a potential oxygen-evolving material, which may be extended to other energy-conversion and storage technologies.