Electronic properties, single walled carbon nanotubes

The electronic properties of single-walled carbon nanotubes have been studied theoretically using different methods[4-12. It is found that if n — wr is a multiple of 3, the nanotube will be metallic otherwise, it wiU exhibit a semiconducting behavior. Calculations on a 2D array of identical armchair nanotubes with parallel tube axes within the local density approximation framework indicate that a crystal with a hexagonal packing of the tubes is most stable, and that intertubule interactions render the system semiconducting with a zero energy gap[35]. 

Odom, T. W. Huang, J.-L. Kim, R Lieber, C. M. 1998. Atomic structure and electronic properties of single-walled carbon nanotubes. Nature 391 62-64. 

Alvarez, L., Righi, A., Guillard, T., Rols, S., Anglaret, E., Laplaze, D., and Sauvajol, J. L. 2000. Resonant Raman study of the structure and electronic properties of single wall carbon nanotubes. Chem. Phys. Lett. 316 186-90. 

Nanomaterials can also be applied to glucose biosensors to enhance the properties of the sensors and, therefore, can lead to smaller sensors with higher signal outputs. Carbon nanotubes have been incorporated in previously developed sensors and seen to increase the peak currents observed by threefold.89 Platinum nanoparticles and single-wall carbon nanotubes have been used in combination to increase sensitivity and stability of the sensor.90,91 CdS quantum dots have also been shown to improve electron transfer from glucose oxidase to the electrode.92,93 Yamato et al. dispersed palladium particles in a polypyrrole/sulfated poly(beta-hydro-xyethers) and obtained an electrode response at 400 mV, compared to 650 mV, at a conventional platinum electrode.94... 

G. Chiarello et al., Vibrational and electronic properties of hydrogen adsorbed on single-wall carbon nanotubes. Phys. Rev. B 69, 153409 (2004)... 

Research on modeling of endohedral fullerenes within single-walled carbon nanotubes (SWNTs) has received increased attention towards the understanding of their electronic and structural properties [304-307]. However, very recently particular emphasis was given to the endohedral fullerenes N C60 [308-313] and P C60 [314] due to the electron spin on the nitrogen or phosphorus site, respectively. Having an extremely long decoherence time the unpaired electron spin could be used as a qubit within a quantum computer. 

Jouguelet E, Mathis C, Petit P. Controlling the electronic properties of single-wall carbon nanotubes by chemical doping. Chem Phys Lett 2000 318 561-564. 

Intermolecular interactions define crucial characteristics of materials for hydrogen storage materials. This topic is discussed in detail in the chapter by Cheng et al. devoted to molecular dynamics simulations of single-walled carbon nanotubes (SWNT) with molecular hydrogen. The properties of modified SWNTs, in the contribution from Politzer et al., are also analyzed from the point of view of potential applications in molecular electronics. 

Single-walled carbon nanotubes are known to possess extraordinary strength.138 Mechanical properties of BN nanotubes would be worthy of exploration. Unlike carbon nanotubes, BN nanotubes are predicted to have stable insulating properties independent of their structure and morphology. Thus, BN tubes can be used as nano-insulating devices for encapsulating conducting materials like metallic wires. Filled BN nanotubes are expected to be useful in nanoscale electronic devices and for the preparation of nano-structured ceramics. 

Double-walled carbon nanotubes (DWNTs), first observed in 1996, constitute a unique family of carbon nanotubes (CNTs). -2 DWNTs occupy a position between the single-walled carbon nanotubes (SWNTs) and the multiwalled carbon nanotubes (MWNTs), as they consist of two concentric cylinders of rolled graphene. DWNTs possess useful electrical and mechanical properties with potential applications. Thus, DWNTs and SWNTs have similar threshold voltages in field electron emission, but the DWNTs exhibit longer lifetimes.3 Unlike SWNTs, which get modified structurally and electronically upon functionalization, chemical functionalization of DWNTs surfaces would lead to novel carbon nanotube materials where the inner tubes are intact. The stability of DWNTs is controlled by the spacing of the inner and outer layers but not by the chirality of the tubes 4 therefore, one obtains a mixture of DWNTs with varying diameters and chirality indices of the inner and outer tubes. DWNTs have been prepared by several techniques, such as arc discharge5 and chemical vapor depo-... 

It is well known that catalyst support plays an important role in the performance of the catalyst and the catalyst layer. The use of high surface area carbon materials, such as activated carbon, carbon nanofibres, and carbon nanotubes, as new electrode materials has received significant attention from fuel cell researchers. In particular, single-walled carbon nanotubes (SWCNTs) have unique electrical and electronic properties, wide electrochemical stability windows, and high surface areas. Using SWCNTs as support materials is expected to improve catalyst layer conductivity and charge transfer at the electrode surface for fuel cell oxidation and reduction reactions. Furthermore, these carbon nanotubes (CNTs) could also enhance electrocatalytic properties and reduce the necessary amount of precious metal catalysts, such as platinum. 

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