Carbon nanotubes support

Self-supported Carbon Nanotubes through Constraint Synthesis... 

Fig. 7.4 (A) Optical micrograph showing the improvement on the apparent density of the carbon nanotubes synthesized without and under constraint. The total weight of each sample was 7g. (B) Examples of the macroscopic size of the self-supported carbon nanotubes obtained by varying the diameter of the reactor.

Watts PCP, Lyth SM, Mendoza E, SUva SRP et al. (2006) Polymer supported carbon nanotube arrays for field emission and sensor devices. Appl. Phys. Lett. 89 103113-103124. 

Krashenimukov, A. V., Nordlund, K., and J. Keinonen. 2002. Production of defects in supported carbon nanotubes under ion irradiation. Physical Review B 65 165423. 

Hydroxyapatite (CajQ(P04)g(0H)2) has also attracted considerable interest as a catalyst support. In these materials, wherein Ca sites are surrounded by P04 tetrahedra, the introduction of transition metal cations such as Pd into the apatite framework can generate stable monomeric phosphate complexes that are efficient for aerobic selox catalysis [99]. Carbon-derived supports have also been utihzed for this chemistry, and are particularly interesting because of the ease of precious metal recovery from spent catalysts simply by combustion of the support. Carbon nanotubes (CNTs) have received considerable attention in this latter regard because of their superior gas adsorption capacity. Palladium nanoparticles anchored on multiwalled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) show better selectivity and activity for aerobic selox of benzyl and cinnamyl alcohols [100, 101] compared to activated carbon. Interestingly, Pd supported on MWCNTs showed higher selectivity toward benzaldehyde, whereas activated carbon was found to be a better support in cinnamyl alcohol oxidation. Functionalized polyethylene glycol (PEG) has also been employed successfully as a water-soluble, low-cost, recoverable, non-toxic, and non-volatile support with which to anchor nanoparticulate Pd for selox catalysis of benzyl/cinnamyl alcohols and 2-octanol [102-104]. 

Irradiation-Induced Defects in a Silica-Supported Carbon Nanotube... 

Figure 14.6. Schematic illustration of chemical methods to prepare Pt nanoparticles supported carbon nanotubes.

No superconductivity has yet been found in carbon nanotubes or nanotube arrays. Despite the prediction that ID electronic systems cannot support supercon-ductivity[33,34], it is not clear that such theories are applicable to carbon nanotubes, which are tubular with a hollow core and have several unit cells around the circumference. Doping of nanotube bundles by the insertion of alkali metal dopants between the tubules could lead to superconductivity. The doping of individual tubules may provide another possible approach to superconductivity for carbon nanotube systems. 

Carbon nanotubes (CNTs) are a set of materials with different structures and properties. They are among the most important materials of modern nanoscience and nanotechnology field. They combine inorganic, organic, bio-organic, coUoidal, and polymeric chemistry and are chemically inert. They are insoluble in any solvent and their chemistry is in a key position toward interdisciphnary applications, for example, use as supports for catalysts and catalytic membranes [20, 21]. 

Xin and co-workers modified the alkaline EG synthesis method by heating the metal hydroxides or oxides colloidal particles in EG or EG/water mixture in the presence of carbon supports, for preparing various metal and alloy nanoclusters supported on carbon [20-24]. It was found that the ratio of water to EG in the reaction media was a key factor influencing the average size and size distribution of metal nanoparticles supported on the carbon supports. As shown in Table 2, in the preparation of multiwalled carbon nanotube-supported Pt catalysts... 

Wang X, Li WZ, Chen ZW, Waje M, Yan YS. 2006. Durability investigation of carbon nanotube as catalyst support for proton exchange membrane fuel cell. J Power Sources 158 154-159. 

Figure 17.10 Electrocatalytic current (per geometric area) versus potential for glucose oxidation by glucose oxidase in an Os-containing redox polymer supported on carbon nanotubes grown for various periods (times indicated) on carbon paper. Reproduced by permission of ECS—The Electrochemical Society, from Barton et al., 2007.

X. Zhang, J. Zhang, and Z. Liu, Conducting polymer/carbon nanotube composite films made by in situ electropolymerization using an ionic surfactant as the supporting electrolyte. Carbon 43, 2186—2191 (2005). 

Piao, L. et al., Methane decomposition to carbon nanotubes and hydrogen on an alumina supported nickel aerogel catalyst, Catal. Today, 74,145, 2002. 

Van Steen, E., andPrinsloo, F. F. 2002. Comparison of preparation methods for carbon nanotubes supported iron Fischer-Tropsch catalysts. Catalysis Today 71 327-34. 

Guczi, L., Stefler, G., Geszti, O., Koppany, Zs., Molnar, E., Urban, M., and Kiricsi, I. 2006. CO hydrogenation over cobalt and iron catalysts supported over multiwall carbon nanotubes Effect of preparation. Journal of Catalysis 244 24—32. 

Tavasoli, A., Abbaslou, R. M. M., Trepanier, M., and Dalai, A. K. 2008. Fischer-Tropsch synthesis over cobalt catalyst supported on carbon nanotubes in a slurry reactor. Applied Catalysis A General 345 134-42. 

Peng F, Fu X, Yu H, Wang H (2007). Preparation of carbon nanotube-supported Fe203 catalysts and their catalytic activities for ethylbenzene dehydrogenation. New Carbon Mater. 22 213-217. 

Wildgoose, G.G., C.E. Banks, and R.G. Compton, Metal nanopartictes and related materials supported on carbon nanotubes Methods and applications. Small, 2006. 2(2) p. 182-193. 

Sheng, W., et al., Synthesis, activity and durability ofPt nanoparticles supported on multi-walled carbon nanotubes for oxygen reduction. Journal of The Electrochemical Society, 2011. 158(11) p. B1398-B1404. 

Carbon is unique among chemical elements since it exists in different forms and microtextures transforming it into a very attractive material that is widely used in a broad range of electrochemical applications. Carbon exists in various allotropic forms due to its valency, with the most well-known being carbon black, diamond, fullerenes, graphene and carbon nanotubes. This review is divided into four sections. In the first two sections the structure, electronic and electrochemical properties of carbon are presented along with their applications. The last two sections deal with the use of carbon in polymer electrolyte fuel cells (PEFCs) as catalyst support and oxygen reduction reaction (ORR) electrocatalyst. 

Alternative support materials are being investigated to replace carbon black as support in order to provide higher corrosion resistance and surface area. These supports can be classified into (i) carbon nanotubes and fibers (ii) mesoporous carbon and (iii) multi-layer graphene and they are presented in detail in the following section. 

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