Inherent carbonaceous impurities on arc-discharge multiwalled carbon nanotubes and their implications for nanoscale interfaces

This paper presents evidence that strongly adhered carbonaceous surface impurities, intrinsic impurities that accompany multiwall carbon nanotubes (MWCNTs) synthesized by arc-discharge, are a component that cannot be ignored in experiments involving single nanotubes and their interfaces with a second surface. At the interface that forms between a carbon nanotube and a graphitic surface, these impurities can significantly alter the adhesion properties of the underlying nanotube and can cause over 30% scatter in computed interaction energies, similar in magnitude to the scatter reported in experimental measurements involving individual CNTs. Also presented is high-resolution TEM evidence that commonly used purification techniques that are effective at removing larger impurity particles from as-produced arc-discharge MWCNT samples do not remove these strongly adhered carbonaceous surface impurities.