Supercapacitance of solid carbon nanofibers made from ethanol flames

Solid carbon nanofibers (CNFs) made from ethanol flames were used to prepare supercapacitors. Their microstructure, crystallinity, porosity, chemical properties, and electrochemical activity were compared with the multiwalled carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition. The produced CNFs have a unique microstructure with a solid core and porous surface. The specific surface area of CNFs was comparable to that of MWCNTs because of their larger amount of micropores on the surface. The synthesis environment also resulted in abundant functional groups absorbed on the surface of the CNFs. Electrochemical characterization shows that CNFs have much larger capacitance than that of MWCNTs. The capacitance of CNFs consists of both double-layer capacitance contributed by micropores and pseudo-capacitance produced from redox reactions of the absorbed oxygen functional groups. In comparison to the reported MWCNTs-based supercapacitors, the CNF demonstrates more promising potential in energy storage applications because of its larger electrochemical capacitance.