Crystalline/amorphous Ni/NixSy supported on hierarchical porous nickel foam for high-current-density hydrogen evolution

Manufacturing efficient and durable electrodes for alkaline water electrolysis under high-current-density conditions is a great challenge. Herein, Ni/NixSy heterostructure was grown on designed porous nickel foam (PNF) to construct Ni/NixSy-PNF electrode by a facile and scalable method for alkaline hydrogen evolution reaction (HER). The hierarchical porous structure and super-hydrophilic surface of Ni/NixSy-PNF accelerate the mass transfer and bubble detachment at high current densities. Theoretical calculations reveals that the enhanced HER activity of Ni/NixSy heterostructure is attributed to the stronger H2O adsorption. The resulting Ni/NixSy-PNF electrode achieves current densities of 100 and 500 mA cm−2 at low overpotentials of 61 and 121 mV, respectively. When applied for overall water splitting, the Ni/NixSy-PNF||Fe-Ni3S2-PNF electrolyser reaches a current density of 10 mA cm−2 at an extremely low voltage of 1.32 V. This work provides an effective strategy for fabricating high-performance electrodes for practical water electrolysis.