Preparation of iron oxide nanoparticles supported on magnesium oxide for producing high-quality single-walled carbon nanotubes

Fe₃O₄ nanoparticles with a narrow diameter distribution having an average diameter of 10.33nm±2.99nm (average diameter±standard deviation) were prepared by a precipitation method. The Fe₃O₄ nanoparticles were supported on MgO by mixing the MgO nanopowder with the required amount of Fe₃O₄ nanoparticles in water under extensive sonication. Single-walled carbon nanotubes (SWCNTs) were synthesized by the chemical vapor deposition (CVD) of methane over the Fe₃O₄/MgO catalyst. Transmission electron microscopy showed that a large number of SWCNT bundles of nearly uniform diameter were produced by the CVD method. The average diameter of the produced SWCNTs was ca. 1.22nm. Thermogravimetric analysis showed that the weight loss was approximately 19% by oxidation of carbon in the temperature range of 400-680℃. The ratio of the intensity of the D-band to the G-band was 0.03, indicating that the SWCNTs were well-graphitized.