2014, Vol.15, No.3

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 4.82

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

Exceptional progress has been made with chemical vapor deposition (CVD) of graphenein the past few years. Not only has good monolayer growth of graphene been achieved, butlarge-area synthesis of graphene sheets has been successful too. However, the polycrystallinenature of CVD graphene is hampering further progress as graphene property degradesdue to presence of grain boundaries. This review will cover factors that affect nucleation ofgraphene and how other scientists sought to obtain large graphene domains. In addition, thelimitation of the current research trend will be touched upon as well.

Pitch is an attractive raw material for carbon fiber precursors due to its low cost stemming from its availability as a residue of coking and petroleum processes. Ford Motor Company reported a carbon fiber target price of $11.0/kg by using a fast cycle-time manufacturing method with carbon fiber in an inexpensive format, allowing for an average retail price of gasoline of $3.58/gallon. They also recommended the use of carbon fiber with strength of 1700 MPa, modulus of 170 GPa, and 1.5% elongation. This study introduced a ca. 5.5 μm carbon fiber with 2000 MPa tensile strength obtained from a precursor through simple distillation of petroleum residue. Petroleum pitch based carbon nanofibers prepared via electrospinning were characterized and potential applications were introduced on the basis of their large specific surface area and relatively high electrical conductivity.

An attempt was made to investigate the effect of the preparation temperature on the electrocapacitiveperformance of polypyrrole (PPY)/graphene oxide (GO) nanocomposites (PNCs). For this purpose, a series of PNCs were prepared at various temperatures by the cetyltrimethylammoniumbromide-assisted dilute-solution polymerization of pyrrole in presence of GO(wt%) ranging from 1.0 to 4.0 with ferric chloride as an oxidant. The formation of the PNCswas ascertained through Fourier-transform infrared spectrometry, X-ray diffraction spectra,scanning electron microscopy and simultaneous thermogravimetric-differential scanningcalorimetry. The electrocapacitive performance of the electrodes derived from sulphonatedpolysulphone-bound PNCs was evaluated through cyclic voltammetry with reference to Ag/AgCl at a scan rate (V/s) ranging from 0.2 and 0.001 in potassium hydroxide (1.0 M). Theincorporation of GO into the PPY matrix at a reduced temperature has a pronounced effecton the electrocapacitive performance of PNCs. Under identical scan rates (0.001 V/s), PNCsprepared at 10 ± 1°C render improved specific conductivity (526.33 F/g) and power density(731.19 W/Kg) values compared to those prepared at 30 ± 1°C (217.69 F/g, 279.43 W/Kg). PNCs prepared at 10 ± 1°C rendered a capacitive retention rate of ~96% during the first 500cycles. This indicates the excellent cyclic stability of the PNCs prepared at reduced temperaturesfor supercapacitor applications.