Synthesis of high-quality double-walled carbon nanotubes using porous MgO nanowire supported iron oxide as catalyst

Fe2O3/MgO catalyst was prepared by a simple conventional impregnation method, porous MgO nanowire as catalyst support. After calcination at 950 °C for 3 h, MgFe2O4/MgO solid solution was formed, which presents high efficiency for the synthesis of high-quality double-walled carbon nanotubes (DWCNTs) through the thermal chemical vapor deposition (CVD) of methane at 900 °C. The obtained DWCNTs were characterized by high-resolution transmission electron microscopy, thermal gravimetric analysis and Raman spectroscopy. The carbon yield was 29.2 wt%. The growth of the DWCNTs was attributed to the base-growth model. The formation of Fe3C during the CVD process plays key roles in the DWCNTs growth.