Square-Facet Nanobar MOF-Derived Co(3)O(4)@Co/N-doped CNT Core–Shell-based Nanocomposites as Cathode Materials for High-Performance Supercapacitor Studies

[Image: see text] The binary as well as ternary nanocomposites of the square-facet nanobar Co-MOF-derived Co(3)O(4)@Co/N-CNTs (N-CNTs: nitrogen-doped carbon nanotubes) with Ag NPs and rGO have been synthesized via an easy wet chemical route, and their supercapacitor behavior was then studied. At a controlled pH of the precursor solution, square-facet nanobars of Co-MOF were first synthesized by the solvothermal method and then pyrolyzed under a controlled nitrogen atmosphere to get a core–shell system of Co(3)O(4)@Co/N-CNTs. In the second step, different compositions of Co(3)O(4)@Co/N-CNT core–shell structures were formed by an ex-situ method with Ag NPs and rGO moieties. Among several bare, binary, and ternary compositions tested in 6 M aqueous KOH electrolyte, a ternary nanocomposite having a 7.0:1.5:1.5 stoichiometric ratio of Co(3)O(4)@Co/N-CNT, Ag NPs, and rGO, respectively, reported the highest specific capacitance (3393.8 F g(–1) at 5 mV s(–1)). The optimized nanocomposite showed the energy density, power density, and Coulombic efficiency of 74.1 W h.kg(–1), 443.7 W.kg(–1), and 101.3%, respectively, with excellent electrochemical stability. After testing an asymmetrical supercapacitor with a Co(3)O(4)@Co/N-CNT/Ag NPs/rGO/nickel foam cathode and an activated carbon/nickel foam anode, it showed 4.9 W h.kg(–1) of energy density and 5000.0 W.kg(–1) of power density.