Single-wall carbon nanotubes unique properties

Metallic nanoparticles and single-walled carbon nanotubes (SWCNTs) exhibit nanoscale dimensions comparable with the dimensions of redox proteins. This enables the construction of NP-enzyme or SWCNT-enzyme hybrids that combine the unique conductivity features of the nanoelements with the biocatalytic redox properties of the enzymes, to yield wired bioelectrocatalyts with large electrode surface areas. Indeed, substantial advances in nanobiotechnology were achieved by the integration of redox enzymes with nanoelements and the use of the hybrid systems in different bioelectronic devices.35... 

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. 

Nanofillers, carbon nanotubes (CNTs), especially single-walled carbon nanotubes (SWNTs), have attracted a great deal of interest due to their low density, large aspect ratio, superior mechanical properties, and unique electrical and thermal conductivities [1-4], They can find potential applications in many fields, such as chemical sensing, gas storage, field emission, scanning microscopy, catalysis, and composite materials. 

Carbon nanotubes (CNT) are formed by a hollow cylinder formed by a unique carbon sheet forming a single walled carbon nanotube (SWCNT) or concentric carbon sheets with different diameters forming multiwalled carbon nanotubes (MWCNT) with carbon-carbon with sp bonding [75]. The particular cylindrical form of CNT is the principal aspect that provides the quantum confinement effect in the oriented ID nanostructured materials [80]. These characteristics provide the possibUity to increase chemical reactivity and electronic properties of this particular carbon material, which becomes a crucial point for biosensing devices [75]. 

Carbon Nanotubes (CNTs), the third allotrope of carbon next to diamond and graphite, were discovered in 1991. Since then, their exceptional properties, such as extremely high tensile strengths (150-180 GPa) and modulus (640 GPa to 1 TPa), "ballistic thermal conduction (>3000 W/mK for individual tubes) and exceptional electrical conductivity, have been unveiled. These properties are directly attributed to their unique structure. CNTs are long cylinders of covalently bonded carbon atoms, which look somewhat like graphene sheets that have been rolled-up into seamless tubes. The tube ends may be capped by hemi-fullerenes. Single-walled carbon nanotubes (SWCNTs) comprise only one such cylinder, while multi-walled carbon nanotubes (MWCNTs) contain a set of coaxial cylinders, see Figure 1.3. 

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