Modish Designation of Hollow-Tubular rGO-NiMoO4@Ni-Co-S Hybrid Core-shell Electrodes with Multichannel Superconductive Pathways for High-Performance Asymmetric Supercapacitors.

ABSTRACT

The scrupulous designation of hollow and porous electroactive materials incorporating prolific redox-active polyphase transition-metal oxide decorated with polyphase transition-metal sulfide onto rGO (reduced graphene oxide)-supported conductive substrate has never been an easy task due to the very good coordination affair of sulfur toward transition metals. Herein, cost-effective hydrothermal growth followed by a metal-organic framework (MOF)-mediated sulfidation approach is employed to achieve burl-like Ni-Co-S nanomaterial-integrated hollow and porous NiMoO4 nanotubes onto rGO-coated Ni foam (rGO-NiMoO4@Ni-Co-S) as the electrode material for supercapacitors. The open framework of the rGO-Co-MOF template after the etching and sulfidation process not only enables the creation of a tubular structure of NiMoO4 nanorods but also provides convenient ion-electron pathways to promote rapid faradic reactions for the hybrid composite electrode. Owing to the unique hollow and tubular structure, the as-fabricated rGO-NiMoO4@Ni-Co-S electrode exhibits a high specific capacity of 318 mA h g-1 at 1 A g-1 and remarkable cyclic performance of 88.87% after 10,000 consecutive charge-discharge cycles in an aqueous 2 M KOH electrolyte on a three-electrode configuration. Moreover, the assembled rGO-NiMoO4@Ni-Co-S//rGO-MDC (MOF-derived carbon) asymmetric supercapacitor device exhibits a satisfactory energy density of 57.24 W h kg-1 at a power density of 801.8 W kg-1 with an admirable life span of 90.89% after 10,000 repeated cycles.