MWCNTs molecules

Preparation research of SWCNT was also put forth by lijima and his co-worker [3]. The structure of SWCNT consists of an enrolled graphene to form a tube without seam. The length and diameter depend on the kinds of the metal catalyst used in the synthesis. The maximum length is several jim and the diameter varies from 1 to 3 nm. The thinnest diameter is about the same as that of Cgo (i.e., ca. 0.7 nm). The structure and characteristics of SWCNT are apparently different from those of MWCNT and rather near to fullerenes. Hence novel physical properties of SWCNT as the one-dimensional material between molecule and bulk are expected. On the other hand, the physical property of MWCNT is almost similar to that of graphite used as bulk [6c]. 

The aluminum is incorporated in a tetrahedral way into the mesoporous structure, given place to Bronsted acidic sites which are corroborated by FTIR using pyridine as probe molecule. The presence of aluminum reduces the quantity of amorphous carbon produced in the synthesis of carbon nanotubes which does not happen for mesoporous silica impregnated only with iron. It was observed a decrease in thermal stability of MWCNTs due to the presence of more metal particles which help to their earlier oxidation process. 

The samples are named as Fe/Al-MCM41 (nSi/nAl). Pyridine as a molecule probe was adsorbed on dried samples for the acidic sites characterization by FTIR. MWCNTs were synthesized using the CCVD of ethylene as described elsewhere [7]. 

Fig. 9.19 (a) and (b) TEM micrograph of MWCNTs with attached ferritin molecules, (c) Temperature variation of storage modulus E Published with permission from American Institute of Physics)... 

Ferrocene was one of the earliest mediators used [10] but is somewhat hydrophobic so derivatives of the molecule are often employed [39-43]. Ferricyanide can also be used, and the use of MWCNT with this mediator was shown to enhance its effectiveness [33]. Other groups have studied a wide diversity of novel mediator systems such as poly(vinylferrocene-co-acrylamide) dispersed within an alumina nanoparticle membrane [34], ruthenium [35] and osmium [36,37] complexes, and the phenazine pigment pyocyanin, which is produced by the bacteria Pseudomonas aeruginosa [38]. 

This work is to introduce the SERS-active surface prepared by electrodeposition of Ag nanoparticles in MWCNTs for SERS chemical sensor application. R6G, a dye molecule, is chosen as a probe molecule because it has been well investigated by SERS. 

MWCNTs-Nafion nanocomposite. The EDS patterns of MWCNTs-Nafion nanocomposite before and after electrochemical deposition of Ag nanoparticles are shown in Fig. 6.2a, b, respectively. It indicates that C is the major element which is derived from MWCNTs and Nation. The Ag element can be identified in Fig. 6.2b after the electrochemical deposition of Ag nanoparticles. The prepared Ag-MWCNTs-Nafion nanocomposite was used to detect the typical SERS active probe molecule such as R6G. For the determination, the Ag-MWCNTs-Nafion-nanocomposite-modified ITO substrates were placed on the bottom of a liquid cell with 35 mF aqueous solution. Two control experiments at the Ag-coated and Ag-carbon black (CB)-Nafion-coated ITO substrates were performed for comparison. The Raman spectra of 10 " M R6G in aqueous solution at the surfaces of MWCNTs-Nafion, Ag, Ag-CB-Nafion, and Ag-MWCNTs-Nafion-modified ITO substrates are shown in Fig. 6.3a-d, respectively. The peaks at 1,186, 1,310,... 

In conclusion, it has been shown that the SERS techniques offer a means of sensitive detection of probe molecules. An efficient and simple SERS-active substrate prepared by electrodeposition of Ag on MWCNTs has been developed. The prepared Ag-MWCNT nanocomposites exhibited good SERS performance and also featured a simple application process. The technique may have a potential use for in situ determination of analytes. Therefore, such a work will lead to a very promising future for applications in SERS chemical sensors. 

Fig. 9 (a) Dendron functionalized-MWCNT complexed with Ru4(POM) molecules and (b) scheme of a complete electrochemical cell. Adapted from [149]... 

Rolf Landauer proved that the minimum resistance of any single-channel wire (composed of atoms or molecules or polymers), measured between any two macroscopic electrodes, is the quantum of resistance R = (h/2e ) = 12.91 kQ, where h is Planck s constant, and e is the electronic charge. In Milestone Two, this Landauer quantum of resistance was measured by Walt de Heer and coworkers at room temperature between a multiple-walled carbon nanotube (MWCNT), glued to a conducting AFM tip, and a pool of liquid... 

Other nano-fillers have also investigated. Cao et al. [253] reported the utilization of multiwalled carbon nanotubes (MWCNTs) as filler-reinforcement to improve the performance of plasticized starch (PS). The PS/MWCNTs nanocomposites were prepared by a simple method of solution casting and evaporation. The results indicated that the MWCNTs dispersed homogeneously in the PS matrix and formed strong hydrogen bonding with PS molecules. Besides the improvement of mechanical properties, the incorporation of MWCNTs into the PS matrix also led to a decrease in the water sensitivity of the PS-based materials. 

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