Controlled synthesis of NiWO4 combined with NiSe2 with heterostructure on nickel foam for efficient overall water splitting

In recent years, hydrogen energy as a new type of green energy has been attracted more attention by people, what is noteworthy is that electrolysis of water for producing hydrogen is recognized as method of high efficiency and easy to operate. In this paper, NiWO4 @NiSe2/NF with heterostructure bifunctional electrocatalyst was firstly designed and synthesized by two-step hydrothermal method and its electrochemical performance was researched in an alkaline medium. Driving a current density of 10 mA cm−2 requires only overpotential of 258 mV for oxygen evolution reaction (OER) (Tafel slope: 38.93 mV dec−1) and overpotential of 132 mV for hydrogen evolution reaction (HER) (Tafel slope: 70.52 mV dec−1) for NiWO4 @NiSe2/NF. What is noteworthy is that NiWO4 @NiSe2/NF//NiWO4 @NiSe2/NF electrode couple shows a low cell voltage of 1.60 V with superior 15 h of durability for overall water splitting. Its excellent catalytic performance is mainly attributed to the unique nanosphere structure and the construction of heterogeneous interface. The density functional theory calculation shows that the introduction of the NiSe2 material greatly reduces the Gibbs free energy of hydrogen adsorption, and the introduction of the NiWO4 material greatly enhances the conductivity of the material. This work provides a feasible strategy to replace traditional energy sources.