Highly conductive, porous RuO2/activated carbon nanofiber composites containing graphene for electrochemical capacitor electrodes

RuO2/activated carbon nanofiber (ACNF) composites containing graphene are prepared by a simple electrospinning method, followed by physical activated carbonation. We investigate the electrochemical properties as supercapacitor electrodes and the structural properties of these RuO2/ACNF materials as a function of the graphene concentration. The porous RuO2/ACNF composites exhibit an improved microstructure in terms of increased surface area, large mesopore volume fraction, and increased electrical conductivity with increasing graphene content. The RuO2/ACNFs with 3 wt% graphene are characterized as having a large specific surface area of up to 1552.2 m(2)g(-1), mesopore volume fraction up to 53%, high electrical conductivity of over 0.59 Scm(-1), gravimetric capacitance of 180.2 Fg(-1) and energy density of 20.4-15.3 Whkg(-1) over a power density range of 400-10,000 Wkg(-1) in 6.0 M KOH electrolyte. These results suggest that RuO2/ACNF with graphene offers the benefits of low resistance for charge diffusion and a short pathway for ion transportation. Therefore, RuO2/ACNF with graphene shows good capacitive behavior when applied as an electrode material for supercapacitors in terms of high rate capability, large capacitance, and more efficient energy density. (C) 2015 Elsevier Ltd. All rights reserved.