Ethylene flame synthesis of well-aligned multi-walled carbon nanotubes

A stainless steel grid baked by a propane–air premixed flame had iron, chromium and nickel oxide deposits on the grid surface. With this grid, entangled and curved shape multi-walled carbon nanotubes (MWNTs) were harvested from an ethylene–air diffusion flame with yield rate of 3 mg/min. Nitrogen addition to the flame was found to straighten the entangled tubes probably by lowering the flame temperature. A cobalt-electrodeposited stainless steel grid was finally applied to the nitrogen-diluted ethylene diffusion flame; well-aligned and well-graphitized carbon nanotubes consisting of 20 nm diameter and 10 μm long element tubes were obtained.