Frontier performance of in situ formed α-MnO(2) dispersed over functionalized multi-walled carbon nanotubes covalently anchored to a graphene oxide nanosheet framework as supercapacitor materials

α-MnO(2) has been recognized as a potential material for supercapacitor applications because of its abundance, cost-effectiveness, environmental-benign nature and high theoretical specific capacitance (C(sp)) of 1370 F g(−1). In this study, we succeeded for the first time to achieve the theoretical C(sp) with 3D multi-walled carbon nanotubes (MWCNTs) horizontally dispersed on 2D graphene oxide (GO) nanosheet framework-supported MnO(2) ternary nanocomposites synthesized by a simple precipitation method. The in situ formation of α-MnO(2) and GO, and the growth of 3D MWCNT/GO framework took place simultaneously in a strong acidic suspension containing functionalized-MWCNTs, graphite, NaNO(3) and KMnO(4). Characterizations of the composites synthesized by varying % wt MWCNTs were performed with state-of-the-art techniques. These composites were characterized to be semi-crystalline and mesoporous in nature, and the scrupulous analyses of field emission scanning electron microscopic images showed MnO(2) nano-flower distributed over 3D MWCNTs dispersed-on-GO-nanosheet frameworks. These composites deposited on a graphite electrode exhibited an ideal supercapacitive behavior in an Na(2)SO(4) solution measured via cyclic voltammetry and chronopotentiometry. Optimum contents of MnO(2) and MWCNTs in the composites showed a maximum C(sp) of 1380 F g(−1) with satisfactory energy and power densities compared in the Ragone plot. An ascending trend of C(sp) against the charge–discharge cycle number studied for 700 cycles was noticed. Well-dispersion of α-MnO(2) nanoparticles throughout 3D MWCNTs covalently-anchored to the GO nanosheet framework is discussed to aid in achieving the frontier C(sp) of MnO(2).