Single-wall carbon nanotubes (SWCNTs) are commonly dispersed via sonication in a solvent prior to functionalization. We show that solvents such as dichloromethane, chloroform, 1,2-dichloroethane, and o-dichlorobenzene lead to an upward shift in the Raman response of the SWCNTs. We have used o-dichlorobenzene as a model molecule to explain this effect, and an upward shift of 9 cm(-1) is observed in the D* band. This blue shift is associated with p-type doping and is triggered only when the nanotubes are sonicated in the solvent. Sonication decomposes the chlorinated solvents, and new species (Cl2 and HCl(g)) are formed. The catalytic Fe nanoparticles inherently present in the nanotubes are etched by chlorine and hydrogen chloride to form iron chlorides during sonication in the solvent. The dopant was identified by X-ray photoelectron spectroscopy. With such knowledge of doping, the choice of solvent becomes crucial for any chemical reaction and can be intentionally tuned to produce SWCNTs films for electronics applications.

Carbon nanotubes are an intriguing new form of carbon, comprising molecular-scale cylinders of nanometer diameter and micrometer to centimeter lengths. They exhibit many extraordinary mechanical and electrical properties and have a wide variety of anticipated applications. However, to realize these potential applications, chemists need to develop means by which to manipulate these nanotubes in a predictable and controllable way. Novel sidewall-modified carbon nanotubes functionalized with polymers, such as poly(methyl methacrylate) (PMMA), have been prepared to gain control over the properties of nanocomposites on the molecular level. Characterization of these materials has been limited by their insolubility in organic solvents. Here the interaction between the carbon nanotube and the polymer has been studied through the use of solid-state nuclear magnetic resonance (NMR) and scanning tunneling microscopy (STM). Fast magic-angle spinning (30 kHz), to achieve high-resolution 1H NMR, together with advanced pulse sequences such as 1H double quantum NMR with the BABA (back-to-back) sequence, and heteronuclear 1H−13C sequences, are used to demonstrate the association of the initiator moieties and polymers with the surface of the nanotubes. The findings are supported by STM data of nanotubes before and after functionalization with the initiator groups.

Using the Bingel reaction as a model for side-wall functionalization of single-walled carbon nanotubes, we report the discovery of highly regular, long-distance (several nanometer) patterns and examine the conditions for the occurrence of such patterns, possibly due to longrange induced reactivity. Varying periodicities of the patterns have been observed via scanning tunneling microscopy and are attributed to nanotube geometry. Patterns are most prominent on medium heavy functionalized nanotubes and likely tied to a nucleophilic reaction mechanism.

We process one-dimensional (1D) NiO nanostructures in anodized alumina templates starting from electrochemically deposited Ni nanotubes (NTs), and characterize their morphology-dependent supercapacitance behavior. The morphology of the 1D NiO nanostructures is controlled by the time of annealing at 450°C. After 25 min of annealing, the NTs start to close but maintain the tubular structure, and after a further 300 min of annealing time, the tubes are completely closed and nanorods (NRs) are formed. We show that the structures obtained are highly promising for supercapacitor applications; the performance of the NiO NT structure is with a specific capacitance of 2,093 F/g, the highest ever obtained for NiO, approaching the theoretical capacitance of this material. A suitable combination of nanocrystalline grain size and the high surface area akin to the tubular structure is responsible for this high performance. In contrast, the NiO NR structure is characterized by lower performance (797 F/g). A further attribute of the proposed structure is its high stability against galvanostatic charging-discharging cycling at high current densities, with almost no alteration to performance after 500 cycles.