Hierarchical flower-like amorphous nickel sulfide/crystalline CoFe layered double hydroxide heterostructure for overall water splitting

The construction of a bifunctional electrocatalyst with excellent performance and low cost plays a key role in the application prospect of renewable energy. Herein, nickel sulfide/CoFe layered double hydroxide heterostructures on nickel foam (NiS/LDH/NF) have been constructed by using hydrothermal and electro-deposition methods. The amorphous nickel sulfide is deposited on the surface of crystalline LDH mesh-like nanosheets to form a hierarchical flower-like structure. The deposition of amorphous NiS can control the morphology and modulate the electronic structure of NiS/LDH/NF. The obtained NiS/LDH/NF is employed as a bifunctional catalyst for overall water splitting, which can achieve a current density of 10 mA cm−2 at a low voltage of 1.51 V in 1 M KOH. The results show that the high electrocatalytic activity is ascribed to the formation of amorphous NiS/crystalline LDH heterostructure with abundant surface defects and active sites. The synthetic strategy holds a great promise for accelerating the development of hydrogen energy by highly efficient electrocatalytic production of hydrogen.