Extracting subnanometer single shells from ultralong multiwalled carbon nanotubes.

Hong, Byung Hee; Small, Joshua P; Purewal, Meninder S; Mullokandov, Asher; Sfeir, Matthew Y; Wang, Feng; Lee, Ju Young; Heinz, Tony F et al. · Proc Natl Acad Sci U S A · 2005

basic_science · Level V

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Abstract

We report a simple but powerful method for engineering multi-walled carbon nanotubes (MWNTs) by using manipulation by an atomic-force microscope. The successive shell-by-shell extraction process of ultralong MWNTs allows the exposure of the innermost single-walled carbon nanotubes (SWNTs), which have diameters as small as approximately 0.4 nm. The inner-shell extraction process changes the electrical characteristics of the MWNTs. Whereas the outer hollowed-out nanotubes show either metallic or semiconducting character, the innermost SWNTs of small diameter exhibit predominantly metallic transport properties.