Synthesis of carbon–Fe3O4 coaxial nanofibres by pyrolysis of ferrocene in supercritical carbon dioxide

Carbon–Fe3O4 coaxial nanofibres with a diameter around 100 nm were synthesized by pyrolysis of ferrocene in supercritical CO2 at 400 °C. The single crystal Fe3O4 cores of the coaxial nanofibres are continuous, and the carbon shell is rich in H. The M–H hysteresis loop for the nanorodes measured at room temperature shows a saturation magnetization of 27.5 emu/g, much lower than 92 emu/g of the corresponding bulk material. This is attributed the considerable mass of the carbon shell and the nanoscale and anisotropy of the magnetite nanorods. A possible mechanism was proposed.