Efficiently Designed Three-Dimensional Architecture of CoMnO Decorated VCT MXene for Asymmetric Supercapacitors.

The structure, morphology, stoichiometry, and chemical characterization of the VCT MXene, CoMnO, and VC@CoMnO nanocomposite, prepared by using a soft template method, have been studied. The electron microscopy studies reveal that the VC@CoMnO composite incorporates mesoporous spheres of CoMnO within the 2D layered structure of MXene. The specific capacitance of the composite electrode is ∼570 F g at 1 A g, which is significantly higher than that of the sum of the individual components. It also exhibits great rate capability and a Coulombic efficiency of ∼96.5% over 10000 cycles. An asymmetric supercapacitor prototype created with VC@CoMnO//activated carbon outperformed other reported ASCs in terms of achieving a high energy density of 62 Wh kg at a power density of 440 W kg. The improved response of VC@CoMnO and ASC is attributed to the enhanced active area available for charge transfer and the synergistic interaction between CoMnO spherical particles and nanolayered MXene. Supporting density functional theory (DFT) calculations are performed to understand the impact of composite heterojunction formation on its detailed electronic structure. Our atomistic simulations reveal that by incorporating CoMnO in VC, the density of electronic states at the Fermi level increases, boosting the charge transfer characteristics. These modifications in turn enhance the charge storage capabilities of heterojunction. Finally, the merits of the VC@CoMnO composite electrode are discussed by comparing it with those of other existing high-performance MXene-based composite electrodes.