▎ 摘　　要

A robust one-step protocol is provided to prepare the nanocomposite of reduced graphene oxide//Mn3O4 (rGO//Mn3O4) as electrodes for a symmetric supercapacitor, inheriting the superb faradic capacity of manganese oxides, excellent electrical conductivity and electrochemical stability of graphene nanomaterial. KMnO4 is utilized as the precursor of cube-shaped /Mn3O4 particle in the one-step reduction process with Na2SO3 as the reductant, while rGO is reduced from graphene oxide in the same procedure, simultaneously. As a result, the as-prepared rGO//Mn3O4 composite exhibits enhanced electrochemical properties when fabricated as a supercapacitor device, reaching a high specific capacitance of 243 F/g at 0.5 A/g, and 82.3% capacitance retention remained after 1000 cycles at a current density of 5 A/g. As a symmetric supercapacitor device, the energy density reaches 27.92 Wh/kg at the power density of 277.78 W/kg. (C) 2020 Elsevier B.V. All rights reserved.