Graphitic Carbon Nanofibers Synthesized by the Chemical Vapor Deposition (CVD) Method and Their Electrochemical Performances in Supercapacitors

Graphitic carbon nanofibers were synthesized by chemical vapor deposition of methane and acetylene on the γ-alumina-supported nickel catalyst. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption, X-ray diffraction (XRD), and Raman spectroscopy were used to examine the structure and the graphitic degree of carbons. The results show that carbons derived from methane consist of a more graphitic structure compared to acetylene-based carbons. The temperature and the catalyst loading affected the graphitic structure further; i.e., the higher the temperature and the catalyst loadings, the better the graphitic structure. The electrochemical performance of synthesized carbons in 1 M H 2 SO 4 revealed that the methane-based carbons show very stable charge/discharge performance in the whole range of investigated current loadings (viz., 0.05 and 3 A g −1 ), owing to the graphitic structure and thus resulting from the good charge propagation, particularly at high loads. On the other hand, acetylene-based carbons provide greater gravimetric capacitance values as a result of structural defects, but consequently, the capacitance drops at high current loads.