3D in-situ hollow carbon fiber/carbon nanosheet/Fe3C@Fe3O4 by solventless one-step synthesis and its superior supercapacitor performance

Abstract

Herein, 3D in-situ hollow carbon fiber/carbon nanosheet/Fe3C@Fe3O4 (h-CNF/CNS/Fe3C@Fe3O4) was constructed using ferrocene and oleic acid by a solventless one-step process that did not require additional filtering, neutralization, drying, or calcination steps. The iron-oleate chelating structure that self-assembled during annealing facilitated the fabrication of 3D in-situ h-CNF/CNS/Fe3C@Fe3O4 by undergoing graphitization at 600°C. This carbon shell of the 3D in-situ h-CNF/CNS/Fe3C@Fe3O4 was derived from the two cyclopentadienyl rings in ferrocene. This hybrid material made from economically cheap oleic acid exhibited superior supercapacitive behavior: high specific capacitance of 327Fg−1 at 5mVs−1 and 210Fg−1 at 10mVs−1, good rate capability of 60Fg−1 at 10Ag−1 (compared to 70Fg−1 at 1Ag−1 for pure Fe3O4), and superior retention of 108% after 6000 cycles at 100mVs−1. These superior supercapacitive properties were ascribed to the 3D graphitic h-CNF/CNS for enhancing electrical conductivity and the carbonaceous shell over Fe3C@Fe3O4 core for buffering the bulk expansion of iron-related particles.