Electrical current-induced structural changes and chemical functionalization of carbon nanotubes

Abstract

We demonstrate that high current densities, combined with air exposure can slice, weld, and chemically functionalize multiwalled carbon nanotubes (CNTs) with carboxyl and allyl moieties, and alter the electrical properties. The conductance of thin film assemblies of CNTs increases by 150%, indicating that the increase in the number of low-resistance pathways caused by CNT junction formation offsets the conductance decrease expected from defect creation, surface functionalization, and fissure. Such welded high-conductance CNT networks of functionalized CNTs could be useful for device and sensor applications, and may serve as high mechanical toughness mat fillers that are amenable to integration with nanocomposite matrices.

Current Progress on the Chemical Modification of Carbon Nanotubes

“…In a similar approach, Ramanath and co-workers extended the functionalization of CNTs by focused-ion-beam irradiation. The authors showed that nanoparticles, fluorescent microspheres, an amino acid, or a metalloprotein could be assembled on CNT surface without aggressive wet chemical oxidation.…”

Electrostatic-Force-Directed Assembly of Ag Nanocrystals onto Vertically Aligned Carbon Nanotubes

“…Carbon nanotubes (CNTs) , have attracted interest because of their small diameter, large surface-to-volume ratio, great structural integrity, high electrical and thermal conductivity, good thermal and chemical stability, and exceptional strength and resilience. − Functionalization of CNTs with various chemical groups , and nanocrystals − can further enhance the properties of CNTs, and CNTs have been considered as superior supports for nanocrystal catalysts. , In fact, hybrid materials consisting of nanocrystals distributed on the surfaces of CNTs could potentially display not only the unique properties of nanocrystals , and those of nanotubes − but also additional novel properties. Recently, such CNTs with nanocrystals have been shown to be promising for various energy applications including solar cells, , fuel cells, , Li−ion batteries, and hydrogen storage. , …”

Sonochemical Optimization of the Conductivity of Single Wall Carbon Nanotube Networks

“…In general these strategies can be divided into two groups: a pre-deposition functionalization (functionalization of the SWCNT material before the network is made) and a post-deposition functionalization. The latter case again can be divided by different approaches which are: a) direct cross-shell linking between individual CNTs by irradiation with electrons [19] or UV light, [20] and by current induced structural changes [21] or b) various ways of chemical functionalization, such as adsorbing individual molecules with functional groups, [22][23][24] coating with polymers containing functional groups [5,[25][26][27] and covalent bonding of functional groups. [28] In all cases, the functional groups act as electron donors/acceptors and the increased conductivity can be explained in terms of doping of semiconducting SWCNTs, which are the majority in bulk SWCNT samples.…”