A step towards controlled-diameter single walled carbon nanotubes

This research treats a particularly challenging undertaking in carbon nanoscience: controlling the diameter distribution of single walled carbon nanotubes (SWCNTs) grown using CVD. To do so requires the fabrication of well-separated and monodispersed catalytic metal nanoparticles which can be uniformly distributed on a substrate. We propose a new strategy involving the preparation of a monolayer of chemisorbed nickel acetylacetonate which is shown by infrared spectroscopy and coupled thermogravimetric–mass spectrometry analyses to be anchored to the surface silanol groups of the substrate. After decomposition of this precursor, the nickel remains bonded with these surface silanol groups which upon further heating results in good dispersion of the nanoparticles over the silica surface. Using this catalyst, SWCNTs with a very discrete chiral preference and a narrow diameter distribution were synthesized at moderate temperature. This work thus opens new perspectives for the fabrication of uniform-diameter carbon nanotubes.