Electrospun Carbon Nanofibers with in Situ Encapsulated Co₃O₄ Nanoparticles as Electrodes for High-Performance Supercapacitors.

A facile electrospinning method with subsequent heat treatments is employed to prepare carbon nanofibers (CNFs) containing uniformly dispersed Co3O4 nanoparticles as electrodes for supercapacitors. The Co3O4/CNF electrodes with ∼68 wt % active particles deliver a remarkable capacitance of 586 F g(-1) at a current density of 1 A g(-1). When the current density is increased to 50 A g(-1), ∼66% of the original capacitance is retained. The electrodes also present excellent cyclic stability of 74% capacity retention after 2000 cycles at 2 A g(-1). These superior electrochemical properties are attributed to the uniform dispersion of active particles in the CNF matrix, which functions as a conductive support. The onionlike graphitic layers formed around the Co3O4 nanoparticles not only improve the electrical conductivity of the electrode but also prevent the separation of the nanoparticles from the carbon matrix.