Square-Facet Nanobar MOF-Derived Co<sub>3</sub>O<sub>4</sub>@Co/N-doped CNT Core–Shell-based Nanocomposites as Cathode Materials for High-Performance Supercapacitor Studies
Swapnajit V. Mulik, Suprimkumar D. Dhas, A.V. Moholkar, Vinayak G. Parale, Hyung‐Ho Park, Pramod A. Koyale, Vijay S. Ghodake, Dillip K. Panda, Sagar D. Delekar
Abstract
High Resolution Image Download MS PowerPoint Slide 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.