Synthesis of carbon–silica core–shell nanofibers from a dispersion of fluorinated carbon nanofibers in solvated polysiloxane

Carbon–silica core–shell fibers (which unusually consist of carbon nanofibers coated with silica) were synthesized using a two-step process. First, fluorination of carbon nanofibers (CNFs) allows their homogenous dispersion into a polysiloxane matrix. A longlife dispersion of nanofibers in solvated polysiloxane has been prepared. Second, the polysiloxane/fluorinated carbon was thermally treated in air until 700 °C. Defluorination and conversion of polysiloxane into silica occur and result in carbon–silica core–shell fibers. The thermal treatment of the polysiloxane/carbon and the resulting silica/carbon–silica core–shell nanostructures were investigated using solid state nuclear magnetic resonance using 19F, 13C 1H, and 29Si nuclei, X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies.