Coupling of Nickel Boride and Ni(OH)₂ Nanosheets with Hierarchical Interconnected Conductive Porous Structure Synergizes the Oxygen Evolution Reaction

Earth-abundant and highly-efficient electrocatalysts for oxygen evolution reaction (OER) are urgently desired to realize the large-scale storage and conversion of renewable energies. In this work, we develop a hierarchical porous electrocatalyst structure utilizing Ni(OH)₂ nanosheets directly synthesized on Ni foam as the conductive and interconnected supports. By coupling with amorphous Ni−B nanoparticles, this hybrid catalyst exhibits dramatically enhanced electrocatalytic activities and durabilities towards OER. In specific, along with the optimized Ni−B loading, this catalyst requires only an impressively small overpotential of 300 mV to drive a current density of 100 mA cm⁻² for oxygen evolution in 1 M KOH electrolyte. Meanwhile, it also yields a small Tafel slope of 49 mV dec⁻¹ and a superior long-term stability. All these results evidently indicate that the hierarchical hybridization of Ni−B with Ni(OH)₂ on Ni foam can effectively synergize the oxygen evolution, opening up a new vista for designing high-performance transition metal-based nanostructures in the field of electrochemical water splitting.