Synthesis of Multiwalled Carbon Nanotubes using Natural Iron-Containing Minerals

We introduce a novel approach for synthesizing multiwalled carbon nanotubes (MWNTs) via chemical vapor deposition. Natural iron-containing minerals are treated with hydrofluoric acid, calcinated in argon, and reduced in hydrogen, resulting in uniform iron-containing silicate nanoparticles, which catalyze MWNT growth in acetylene (C$_{2}$H$_{2})$. As-grown MWNTs are characterized using electron microscopy and small angle neutron scattering. Through systematically varying C$_{2}$H$_{2}$ flow rate, growth temperatures and time, optimal conditions have been determined for synthesizing large quantities of uniform and clean MWNTs.