Environmental Engineering Reference
In-Depth Information
Fig. 17 Schematic illustration of the formation process of carbon nanofiber/graphene composite
paper. Reprinted with permission from [ 78 ]. Copyright (2012)
reversible capacity of 257 mAh g -1 can be obtained after 10 cycles, which
overpassed the performance of a CNT/cellulose composite paper (140 mAh g -1 ).
Cheng et al. also reported a different method to fabricate graphene/cellulose
composite paper by simply filtering a graphene nanosheets suspension through a
cellulose filter paper [ 77 ]. During filtration, the graphene suspension penetrated
throughout the filter paper, and graphene nanosheets were anchored to the cellu-
lose fibers by electrostatic interaction. As the process continued, the voids of the
filter paper were gradually filled with graphene nanosheets, a composite paper with
graphene nanosheets distributed through the macroporous texture of the filter
paper was achieved. Benefiting from the structural characteristics, when tested as
supercapacitor electrode with H 2 SO 4 -PVA gel electrolyte at 1 mV s -1 , the
graphene/cellulose paper electrodes show good rate capability and long cyclic
stability with a capacitance per geometric area of 81 mF cm -2 , which is equiva-
lent to a gravimetric capacitance of 120 F g -1
of graphene, and retains [99 %
capacitance over 5,000 cycles.
Different with cellulose, carbon nanofibers, which have high surface area,
controllable electronic conductivity, and low cost have already been playing the
leading role in supercapacitor electrodes. However, the performance of carbon
nanofiber as supercapacitor electrodes is still limited by their low power and energy
density. To improve the performance of carbon nanofiber-based supercapacitors,
modifying carbon nanofiber with other electroactive materials is an effective route.
Yan et al. prepared flexible and freestanding carbon nanofiber/graphene composite
paper via a high throughput electrospinning method followed by high-temperature
annealing, in which polyacrylonitrile/graphene/dimethylformamide mixture was
used as electrospun precursor (Fig. 17 )[ 78 ]. The structure characterizations show
that graphene nanosheets homogeneously distributes in the carbon nanofiber,
Search WWH ::




Custom Search