Nanocomposites of Honeycomb Double Layered MnO2 Nanosheets /Cobalt Doped Hollow Carbon Nanofiber for Application in Supercapacitor and Primary Zinc-Air Battery

Abstract

A honeycomb double-layered MnO2 nanosheets were successfully deposited on the inner and outer layers of cobalt-doped hollow carbon nanofibers synthesized via the coaxial electrospinning technology (MnO2/Co-HCNFs) by the hydrothermal method. Benefitting from its distinctive hollow structure nanostructure of Co-HCNFs，honeycomb double-layered nanosheets of MnO2 and higher specific surface area of MnO2/Co-HCNFs, MnO2/Co-HCNFs nanocomposites exhibites an enhanced electrochemical property in supercapacitor and zinc-air battery. The as-prepared sample reveals a higher specific capacitance (446 F/g at 0.5 A/g in 1 M Na2SO4 electrolyte). The asymmetric supercapacitor, assembled with the MnO2/Co-HCNFs nanocomposites as positive electrode and KOH-activated porous carbon nanofibers (PCNFs) as negative electrode (MnO2/Co-HCNFs//PCNF), shows a high energy density and a remarkable cycling stability, which implies the practicability for asymmetric capacitors. In addition, the MnO2/Co-HCNFs nanocomposites display preferable oxygen reduction reaction（ORR）catalytic activity (E1/2=0.842V) compared to commercial 20 wt% Pt/C catalyst (E1/2=0.830V) and long-term stability. Notably, a primary zinc-air battery with the MnO2/Co-HCNFs as the cathode catalyst is fabricated and outweighs the Pt/C catalyst in regard to long-term stability and power density. Figure 1