Synthesis of multi-walled carbon nanotubes by catalytic chemical vapor deposition using Cr2 − xFexO3 as catalyst

Chromium oxide and iron oxide solid solution was used as a catalyst for multi-walled carbon nanotubes synthesis by the catalytic chemical vapor deposition technique. The catalyst was prepared by the solution combustion synthesis method. Natural gas (NG) was employed as a carbon source for the carbon nanotube growth instead of methane, which is typically used. The carbon nanotube synthesis was carried out under H2/NG and Ar/NG atmospheres at 950 °C. The Cr2 − xFexO3 catalyst was capable to produce carbon nanotubes only in H2/NG atmospheres. Partial elimination of the catalyst after the synthesis was possible using a concentrated solution of HNO3.