Strong ion interaction inducing ultrahigh activity of NiCoP nanowires for overall water splitting at large current density

• NiCoP-10 g-125℃ nanowires were prepared by molten salt method. • The strong ions interaction in NiCoP can be realized at the optimized condition. • The high metal loading, large specific surface area and fast charge transfer can be obtained. • NiCoP-10 g-125℃ can show ultrahigh activity and stability under high current density. The design and development of cheap and efficient electrocatalysts are particularly imperative for renewable energy, but still a challenge for overall water splitting (OWS). Herein, The NiCoP-10 g-125℃ with three-dimensional (3D) nanowire structures grown on nickel foam (NF) was successfully prepared by a novel molten salt method (MSM), serving as an excellent bifunctional electrocatalyst. The catalyst only needs minimal overpotential of 159 and 391 mV to gain the large current density of 400 mA cm −2 for HER and OER in 1 M KOH, respectively. Meanwhile, the alkaline electrolyzer assembled by two electrodes requires a cell voltage of 1.83 V to achieve 400 mA cm −2 for OWS and runs stably at 100 mA cm −2 for 100 h without apparent potential decay. Such impressive catalytic performance is mainly attributed to the special molten salt synthesis method which provides a liquid environment with strong ions interaction. This special reaction condition contributes to forming 3D nanowire structures with the advantage of high metal loading, large specific surface area, fast charge transfer, and good mechanical strength. Therefore, this work can offer a new avenue for the synthesis of ultrahigh activity bifunctional electrocatalysts.