Ultrathin needle-like NiMoO4/MoO3 heterostructure for supercapacitor and overall water splitting applications

In this study, the morphology of NiMoO4/MoO3 heterostructure was adjusted by adding various amounts of polyvinylpyrrolidone (PVP) as soft-template agent during in-situ solvothermal growth on nickel foam. The electrochemical and physiochemical properties of the free-binder electrode were studied as a function of PVP contents. By adding a proper amount of PVP, the morphology of NiMoO4/MoO3 nanocomposites changed from the agglomerated spherical nanoparticles to the flower-like morphology with the well-distributed nanoneedle-like building blocks. The flower-like NiMoO4/MoO3 heterostructures showed the highest specific capacitance of 3626 Fg−1 at 1 A g−1 and a rate-capability of 76 % by the increase of current density from 1 to 5 A g−1. In alkaline water splitting application, the flower-like microstructure showed the excellent electrocatalytic activity including the low overpotentials of 169 and 318 mV for hydrogen and oxygen evolution reactions, respectively.