Synthesis of single-walled carbon nanotube-Co-MgO composite powders and extraction of the nanotubes

A carbon nanotube-Co-MgO composite powder is prepared by reducing a Mg0.9Co 0.1O solid solution in H-2-CH4 atmosphere. The oxide matrix and part of the Co catalyst are dissolved by acid treatment without damage to the nanotube s. More than 80% of the carbon nanotubes have either one or two walls. The diameters of the nanotubes are in the range 0.5-5 nm. The utilized method m ay be a real improvement in the low-cost, large-scale synthesis of single- and double-walled carbon nanotubes.