Bimetallic-metal organic framework-derived Ni3S2/MoS2 hollow spheres as bifunctional electrocatalyst for highly efficient and stable overall water splitting

Herein, strongly coupled Ni3S2/MoS2 hollow spheres derived from NiMo-based bimetal-organic frameworks are successfully synthesized for overall water splitting via a one-pot solvothermal method followed by sulfurization. A well-defined hollow spherical structure with a heterointerface between Ni3S2 and MoS2 is constructed using solvothermal and sulfurization processes. Owing to their bimetallic heterostructure, porous hollow carbon structure with large surface area, and numerous exposed active sites, the Ni3S2/MoS2 hollow spheres are found to be efficient electrocatalysts for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The heterostructured Ni3S2/MoS2 hollow spheres show small overpotentials of 303 and 166 mV to reach a current density of 10 mA cm−2 for the OER and HER in 1.0 M KOH, respectively. Furthermore, an overall water-splitting electrolyzer consisting of the Ni3S2/MoS2 hollow spheres as both the anode and cathode requires a very low cell voltage of 1.62 V to drive a current density of 10 mA cm−2 with outstanding long-term stability for 100 h. Our findings offer a new pathway for the design and synthesis of electrochemically advanced bifunctional catalysts for various energy storage and conversion applications.