Double-walled carbon nanotubes DWCNTs

Double-walled carbon nanotubes (DWCNTs) consist of two concentric graphene cylinders. DWCNTs, categorized different from both MWCNTs and SWCNTs, are expected to exhibit mechanical and electronic properties superior to SWCNTs. Endo et al. have suggested that... 

The most common method for the production of carbon nanotubes is hydrocarbon-based chemical vapor deposition (CVD) [97] and adaptations of the CVD process [98, 99], where the nanotubes are formed by the dissolution of elemental carbon into metal nanoclusters followed by precipitation into nanotubes [100]. The CVD method is used to produce multiwalled carbon nanotubes (MWCNTs) [101] and double-walled carbon nanotubes (DWCNTs) [102] as well as SWCNTs [103], The biomedical applications of CNTs have been made possible through surface functionalization of CNTs, which has led to drug and vaccine delivery applications [104,105],... 

CNTs are commonly classified into single-waUed (SWCNTs) and multi-walled (MWCNTs) nanotubes [28]. SWCNTs consist of a single graphene layer rolled up into a hollow cylinder and are either metallic or semiconducting, whereas MWCNTs are comprised of two, three, or more concentrically arranged cylinders and exhibit only metallic character. Double-wall carbon nanotubes (DWCNTs) are the most basic members of the MWCNT family. The special role of DWCNTs should be emphasized, as they are the link between SWCNTs and the more complex MWCNTs and, therefore, of great interest for a fundamental understanding of these novel nanostructures. 

As compared to SWCNTs, the properties of capacitors based on double-wall carbon nanotubes (DWCNTs) were not published so frequently, as pure DWCNTs are very hard to obtain. Basically, DWCNTs and multiwall carbon nanotubes (MWCNTs) have a lower surface area for EDL formation as compared to SWCNTs. On the other hand, a variety of works on capacitive performance of MWCNTs has been published, as they are relatively easily synthesized and are much cheaper than SWCNTs. As dependent on the methods of synthesis and modifications, different types of MWCNTs with different specific surface area values were obtained. Their specific capacitance values obtained in aqueous and nonaqueous electrolytes are from 10 to 100 F/g. However, they are not so high as in the case of ACs. On the other hand, one must point out that bulk capacitance is relatively high because of high bulk density of MWCNTs. Synthesis of MWCNTs is often carried out by pyrolysis of ethylene using catalysts, for example, Fe-Co. 

Double-wall carbon nanotubes (DWCNT). Diameter is between 2 and 4 nm ... 

The spectroelectrochemistry of double-wall carbon nanotubes (DWCNTs) has also been investigated [2,90-97]. Nevertheless, the understanding of the effect of the doping is more difficult in DWCNTs. In general, the charge is located mostly on the outer tubes hence, there is a difference between the doping level of the inner and outer tubes. The distinct doping effects for inner and outer tubes are observed in the RBM modes and in the D and G bands as well. For doped DWCNTs, both the D and G bands split into two components upon electrochemical... 

On the basis of the number of concentric walls, CNTs can be divided into single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) [22]. SWCNTs consist of a single rolled graphite sheet defining a cylinder of 0.4-2 nm of diameter and up to several microns long. MWCNTs can be visualized as concentric and closed graphite tubules with two (double-walled carbon nanotubes, DWCNTs) or several layers of graphite sheet that define a... 

Compositematerialcontainingatleastonephasewithconstituentsofl-lOOmn in size can be termed nanocomposites. Nanoparticles commonly used in the nanocomposite include single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), multi-walled carbon nanotubes (MWCNT), carbon nanofiber (CNF), graphite nanoplatelet (GNP), mont-morillonite (MMT), nanoclay and polyhedral oligomeric silsesquioxanes (POSS). Other nanoparticles, such as SiOj, AljOj, TiOj and nanosilica are also used in the nanocomposite. The potential benefits of the nanoparticles for structural and multifunctional nanocomposites are sunamarized below. 

CNT exist in a wide variety of forms and few of them are single-walled carbon nanotubes—SWCNT (Ma et al. 2010), multiwalled carbon nanotubes—MWCNT, and double walled carbon nanotubes—DWCNT (Stobinski et al. 2010 Sahoo et al. 2010). The aspect ratios of the types of carbon nanotubes are large since their lengths are in the range of several micrometers. Among them, two are the most widely used ... 

Structure in MWCNT. Its individual shells are described as SWCNT, -which can be either metaUic or semiconducting. Because of statistical probabiHty and restrictions on the relative diameters of the indmdual tubes, the MWCNT is usually a zero-gap metal (Lin et al., 2003). Double-walled carbon nanotubes (DWCNT) form a special class of nanotubes because their morphology and properties are similar to those of SWCNT but their resistance to chemicals is significantly improved. 

Carbon nanotubes (CNTs) constitute one of the most important ID materials with its length-to-diameter ratio (aspect ratio) exceeding 1000 [58]. The carbon clusters in CNT are structurally built from graphene sheets rolled up around a central hoUow core into a tube [59]. Carbon nanotubes can be classified into single-walled carbon nanotubes (SWCNT) [60], double-walled carbon nanotubes (DWCNTs) [61] and... 

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