CoOx nanoparticles embedded in porous graphite carbon nanofibers derived from electrospun polyacrylonitrile@polypyrrole core–shell nanostructures for high-performance supercapacitors

Abstract

A novel composite nanostructure of C–CoO_x–C with CoO_x nanoparticles embedded in N-containing porous graphite carbon nanofibers (CNF) is successfully prepared via sintering the electrospun polyacrylonitrile–cobalt acetate tetrahydrate nanofibers covered by a polypyrrole (PPy) sheath that were attained from the chemical vapor-phase polymerization of pyrrole monomers using concentrated nitric acid as both the dopant and oxidant for the first time. The unique configuration with a well-defined morphology possesses a large specific surface area and prominent conductivity contributed to by the catalysis of metallic Co and the external PPy-derived carbon envelope, which could facilitate effective electron transfer and rapid ion penetration in C–CoO_x–C, thus improving its electrochemical performance. As expected, when employed as an electrode active material for supercapacitors, the resultant C–CoO_x–C showed a more acceptable specific capacitance, better rate capability and higher cycling stability than individual CNF and CoO_x nanoparticle-decorated CNF without the coating of a N-doped carbon layer from PPy (C–CoO_x).