Three-dimensional Heterostructures of Co@CuxS Core-shell Nanowire Arrays as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

Abstract Developing low-cost, efficient and stable bifunctional electrocatalysts for overall water splitting is very necessary to meet the demand for green H2 fuel in the near future. In this work, we have developed a novel hierarchical heterostructure of CuxS nanosheets/Co nanowire arrays supported on three-dimensional Ni foam (Co@CuxS NWs/3D-NF) as highly active bifunctional electrocatalysts for both the hydrogen (HER) and oxygen (OER) evolution reactions. Inheriting from the advantage of core-shell heterostructure, mesoporous characteristic and chemical coupling effect between Co core and CuxS shell layer, the as-synthesized Co@CuxS NWs/3D-NF exhibits high catalytic activity toward HER and OER with requiring small overpotential of 104.6 and 292.2 mV to reach current density of 10 mA cm-2, respectively. Furthermore, assembled Co@CuxS NWs/3D-NF-based electrolyzer shows remarkable performance with a low operating voltage of 1.55 V at 10 mA cm-2 and high long-term stability, which offers a favorable evidence for potential of our catalyst in practical application.