Electrochemical water splitting for hydrogen production is a promising solution for the production of renewable and environmentally friendly energy sources, but it is hindered by the sluggish kinetic process of oxygen evolution reaction (OER). Here, a novel hierarchical core-shell nanoarray NiCo/Ni/CuO/CF was synthesized by assembling Ni-Co hydroxide nanosheets directly on the metallic nickel coated CuO nanowires, as a highly efficient electrocatalyst for alkaline OER. This NiCo/Ni/CuO/CF anode exhibited low overpotentials of 246 mV and 286 mV at current densities of 10 mA cm(-2) and 100 mA cm(-2), respectively, and a small Tafel slope of 37.9 mV dec(-1). Moreover, NiCo/Ni/CuO/CF showed robust durability at least 60 h at a current density of 100 mA cm(-2). Detailed investigations verified that the unique nanosheets/nanowires architecture with high conductivity metallic nickel layer can expand the exposure of active sites and accelerate the transport of electrons. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.