Novel functionalization chemistry for carbon nanotubes.
We have uncovered various doping or interaction effects of various molecules to carbon nanotube electrical properties, including amines and water [Kong, JPC, 2001; Shim, JACS 2001; Kim, Nano Lett., 2003]

Our pyrene chemistry on nanotube sidewalls [Chen, JACS, 2001] have led to much follow up on ‘supra-molecular chemistry with nanotubes’.


Hydrogen storage and covalent hydrogenation chemistry.
Towards the development of a useful mechanism for hydrogen storage, we have studied the hydrogenation of single-walled carbon nanotubes with atomic hydrogen using core-level photoelectron spectroscopy and x-ray absorption spectroscopy. We find that atomic hydrogen creates C-H bonds with the carbon atoms in the nanotube walls, and such C-H bonds can be completely broken by heating to 600 C. We demonstrate approximately 65 at% hydrogenation of carbon atoms in the single-walled carbon nanotubes, which is equivalent to 5 wt% hydrogen capacity. We also find that the hydrogenation

is a reversible process [Nikitin, PRL, 2005].

Semiconducting nanowire functionalization.
A simple method is developed to synthesize gram quantities of uniform Ge nanowires (GeNWs) by chemical vapor deposition on preformed, monodispersed seed-particles loaded onto high surface area silica support. Various chemical functionalization schemes are investigated to passivate the GeNW surfaces using alkanethiols and alkyl Grignard reactions. The stability of functionalization against oxidation of germanium for various alkyl chain lengths is elucidated by X-ray photoelectron spectroscopy. Among all schemes tested, long chain alkanethiols (≥ C12) are found to impart the most stable GeNW passivation against oxidation upon extended exposure to ambient air. Further, the chemically functionalized oxidation-resistant nanowires are soluble in organic solvents and can be readily assembled into close-packed Langmuir-Blodgett films potentially useful for future high performance electronic devices [Wang, JACS, 2005].

[Chen, JACS, 2001]