Chrysanthemum-like FeS/NiS heterostructure nanoarray as a robust bifunctional electrocatalyst for overall water splitting.

The development of a scalable strategy to prepare highly efficient and stable bifunctional electrocatalysts is the key to industrial electrocatalytic water splitting cycles to produce clean hydrogen. Here, a simple and quick one-step hydrothermal method was used to successfully fabricate a three-dimensional core chrysanthemum-like FeS/NiS heterogeneous nanoarray (FeS/NiS@NF) on a porous nickel foam skeleton. Compared with the monomer NiS@NF, the chrysanthemum-like FeS/ NiS@NF heterostructure nanomaterials have improved catalytic performance in alkaline media, showing low overpotentials of 192 mV (η) and 130 mV (η) for OER and HER, respectively. This study attests that integrated interface engineering and precise morphology control are effective strategies for activating the Ni/Ni coupling, promoting charge transfer and improving the intrinsic activity of the material to accelerate the OER reaction kinetics and promote the overall water splitting performance. The scheme can be reasonably applied to the design and development of transition metal sulfide-based electrocatalysts to put into industrial practice of electrochemical water oxidation.