Study of catalytic properties of sol-gel-derived CoO$_x$–SiO$_2$ film systems by the example of the growth of carbon nanomaterials

Film catalytic samples in the Si–Co–O system in the composition range from 15 to 90 mol% Co have been prepared using the sol-gel technology. Carbon nanomaterials have been fabricated by pyrolytic synthesis using these films as catalysts. Raman spectroscopy of materials has shown that multiwalled carbon nanotubes are formed by pyrolysis on catalytic films containing Co$_3$O$_4$. The dependence of the carbon material length on the synthesis time has been considered. It has been shown that the average growth rate of tubes and fibers is $\sim$ 3 $\mu$m/min.