Functionalization of Carbon Materials with Metals
Wright, Kourtney Dawn
Barron, Andrew R.
Doctor of Philosophy
The functionalization of carbon nanotubes (CNTs) with metals has been shown to produce materials with interesting and useful properties which are different from the isolated constituents. Although metal atoms and particles have been attached to CNTs in a variety of different ways, there is a need for the development of novel approaches in many cases. In this work, SWNTs and other conjugated carbon materials were deposited with copper and Group 6 metals. In attempting to functionalize SWNTs with Group 6 metal atoms for electronics applications, we found that the formation of such species is very sensitive to oxidation by adsorbed/bound oxygen and by oxidized residual catalyst material. Annealing and acid treating the SWNTs allowed for the addition of some zero valent metals, while the use of very high purity SWNTs and graphene allowed for the deposition of primarily zero valent Group 6 metals. As a result of these oxidation issues with SWNTs and because of the limited characterization methods available for SWNTs, we used C60 fullerene to study complexes of conjugated carbon systems with copper(I) and chromium(0). Although the synthesis of an η6-C60-Cr(0) complex was unsuccessful, 1H NMR experiments did suggest the formation of an η2-C60-Cu(I) complex. These results suggest that similar complexes with SWNTs would also be stable. This work also describes the uniform deposition of copper(0) seed particles with a narrow size distribution on pyridine functionalized SWNTs, which may be used as precursor for the development of more consistent Cu-CNT composites. The use of pyridine functional groups was found to be crucial in the formation of the desired copper seeds, and bonding between the seeds and the pyridine groups was verified using 1H NMR and UV-visible spectroscopic experiments.
Single-walled carbon nanotubes; Group 6 metals; copper-carbon nanotube composites; carbon nanotube-metal hybrids; organometallic fullerene complexes