Open and porous NiS2 nanowrinkles grown on non-stoichiometric MoOx nanorods for high-performance alkaline water electrolysis and supercapacitor

Abstract

Hierarchical hybrid heterostructures are regarded to be promising materials for highly efficient bifunctional electrocatalysts and high-performance supercapacitors due to their intriguing morphological features and remarkable electrochemical properties. Herein, we demonstrate the rational construct of cost-effective MoOx@NiS2 hybrid nanostructures as bifunctional electrocatalysts and the electrode material of supercapacitor. Microstructural analysis shows that the hybrid is a kind of hierarchical heterostructure composed of open and porous NiS2 nanowrinkles in situ grown on non-stoichiometric MoOx nanorods, which greatly improves the conductivity, and effectively maximized the electrochemical surface area. As expected, the MoOx@NiS2 hybrid show remarkable electrocatalytic performance in alkaline media, such as overpotentials of 101 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and 278 mV at 20 mA cm−2 for oxygen evolution reaction (OER), and a low cell voltage of 1.62 V to deliver a current density of 10 mA cm−2. Moreover, the hybrid nanostructures present a high specific capacitance 1050 A/g at 1 A/g with ultra-long stability in 6 M KOH. The strategy proposed here introduces a new perspective about the development of efficient earth-abundant bifunctional elecrocatalysts and electrode materials for superior energy conversion and storage devices.