Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique

Carbon nanohybrid material (CNF/gamma-Fe2O3) was obtained via a modified sol-gel technique consisting of two steps: functionalization of carbon nanofibers (CNF) in H2SO4/HNO3 followed by synthesis using Fe(NO3)(3)center dot 9H(2)O. As a result, the iron content of the CNF/gamma-Fe2O3 was increased by more than twice from about 40% to about 87% mass percent, compared to the pristine CNF and oxidized CNF specimens, as proved by energy dispersive X-ray fluorescence. Scanning electron microscopy images exhibited "cumulus" on the CNF/gamma-Fe2O3 specimen surface, which showed the highest iron mass percentage, proved by energy dispersive X-ray spectroscopy. Transmission electron microscopy images confirmed attachment of gamma-Fe2O3 cumulus to the inner and outer surfaces of the CNF walls after synthesis. The characteristic peaks of Fe(2)p(3/2) and Fe(2)p(1/2) appeared in the XPS spectra obtained on CNF/gamma-Fe2O3. In addition, X-ray diffraction (XRD) results indicated formation of gamma-Fe2O3 during the synthesis process. The Raman spectrum of the CNF/gamma-Fe2O3 sample displays peaks with positions close to characteristic peaks of highly crystalline and monodisperse maghemite nanocrystallites. The synthesis of CNF/gamma-Fe2O3 leads to an increase in the hydrophilicity of CNF and magnetic properties at room temperature.