▎ 摘　　要

Hierarchically structured carbon nanofiber/graphene/MnO2(CGMn) hybrid with oxygen and nitrogen functionalities was fabricated in the form of a web via electrospinning as an electrode material for supercapacitors. The CGMn electrode exhibited a high capacitance (225 Fg(-1) at 1 mAcm(-2)), enhanced energy and power efficiency (15.8-13.6 Whkg(-1) in the power density range of 197-4000 Wkg(-1)), and excellent capacitance retention (13% of the initial value at a discharge current of 20 mAcm(-2)) in a 6 M KOH aqueous electrolyte, because of the combination of the double-layer capacitance and the pseudocapacitive character associated with the surface redox-type reactions. The porosity and the number of heteroatoms of the CGMn composite were adjusted by changing the PMMA concentration and carbonization temperature. Therefore, the oxygen-and nitrogen-containing hierarchical porous CGMn hybrid prepared by a simple method is a promising candidate as an electrode material for supercapacitors. (C) 2016 Elsevier Ltd. All rights reserved.