Fabrication of Core–Sheath NiCoP@FePx Nanoarrays for Efficient Electrocatalytic Hydrogen Evolution

Construction of effective, stable, eco-friendly, and earth-abundant electrocatalysts that substitute noble metals for hydrogen evolution reaction (HER) is essential for developing renewable and clean energy. Here we report a layer-by-layer assembly route to fabricate core–sheath structured nanoarrays composed of nickel cobalt phosphide and iron phosphide (NCP@FePx) on a conductive Ni wire by atomic layer deposition (ALD). The as-fabricated multimetallic phosphide exhibits high electrocatalytic activity in both alkaline and acidic media, with small overpotentials of 82.5 and 96 mV at 10 mA cm–2, respectively. The self-supported electrode displays superior long-term stability and favorable durability. The excellent activity is originated from the unique core–sheath structure, and the synergistic effects of the FePx sheath and the NCP core contributed to the enhanced activity. The present ALD-assisted layer-by-layer strategy may provide a general route for the controlled fabrication of nanostructured electrocatalysts with tunable compositions and surfaces.