NiFe/(Ni,Fe)3S2 Core/Shell Nanowire Arrays as Outstanding Catalysts for Electrolytic Water Splitting at High Current Densities

Abstract NiFe/(Ni,Fe) 3 S 2 core/shell nanowire arrays, fabricated with an anodic aluminum oxide membrane templated electrodeposition followed by sulfur ion exchange, are developed as an outstanding catalyst for electrolytic water splitting. Ni nanowire arrays achieve low overpotentials of 112 and 347 mV for the hydrogen evolution reaction at current densities of 10 and 400 mA cm −2 , respectively, whereas ultralow overpotentials of 224 and 305 mV for the oxygen evolution reaction at current densities of 10 and 400 mA cm −2 , respectively, are achieved by NiFe/(Ni,Fe) 3 S 2 core/shell nanowire arrays. The pairing of the Ni nanowire array electrode as the cathode and the NiFe/(Ni,Fe) 3 S 2 core/shell nanowire array electrode as the anode, delivers current densities of 10 and 400 mA cm −2 at ultralow cell voltages of 1.56 and 1.9 V, respectively, for the overall water splitting. The stability of the electrodes is also excellent, exhibiting only minor chronoamperometric decay after 24 h continuous operation at 400 mA cm −2 . The nanowire array‐based electrodes, offering extended reaction surface areas and 1D guided charge transport and mass transfer, prove to be a promising new catalyst architecture design for electrocatalytic processes.