Nanofibers electronic

Structure The polymers are produced as powders or as films on the electrodes. Most conductive polymers have a fibrous structure, each fiber consisting of hundreds of strands of polymer molecules. Techniques exist to control fiber preparation so as to obtain nanofibers expected to be particularly useful as catalyst substrates and in electronic applications (MacDiannid, 2000). 

Fig. 1.16 Schematic representation of the nanofibrous poly (acrylonitrile-co-acrylic acid) membrane containing MWCNTs, as well as the promoted electron transfer from hydrogen peroxide to the immobilized catalase through the PANCAA/MWCNTs nanofiber. Reprinted from [209] (reproduced by permission ofWiley-VCH).

Fig. 14.6). A key is that in many cases solution processing can lead to new structures that are difficult or impossible to attain by other means. This can include, for example, nanofiber arrays, core-shell structures, nanopods, and nanoribbons.30 32 These structures can lead to a variety of new functionalities—from 3D prototyping, to third-generation PV structures, to electronic paper, to a new class of non linear optics, to the ability to order nanostructures at very small length scales and maybe even to the holy grail of the energy field, artificial photosynthesis. Below we briefly discuss how some of these concepts are beginning to be realized.

Application of transmission electron microscopy (TEM) techniques on heterogeneous catalysis covers a wide range of solid catalysts, including supported metal particles, transition metal oxides, zeolites and carbon nanotubes and nanofibers etc. 

The polymer resulting from oxidation of 3,5-dimethyl aniline with palladium was also studied by transmission electron microscopy (Mallick et al. 2005). As it turned out, the polymer was formed in nanofibers. During oxidative polymerization, palladium ions were reduced and formed palladium metal. The generated metal was uniformly dispersed between the polymer nanofibers as nanoparticles of 2 mm size. So, Mallick et al. (2005) achieved a polymer- metal intimate composite material. This work should be juxtaposed to an observation by Newman and Blanchard (2006) that reaction between 4-aminophenol and hydrogen tetrachloroaurate leads to polyaniline (bearing hydroxyl groups) and metallic gold as nanoparticles. Such metal nanoparticles can well be of importance in the field of sensors, catalysis, and electronics with improved performance. 

Figure 14.10 Self-assembly of peptide-amphiphiles into nanofibers (a) a peptide amphi-phile molecule with five distinct regions designed for hydroxyapatite mineralization, (b) a schematic of molecular self-assembly, and (c) a negatively stain transmission electron microscopy image of the nanofibers. Reprinted from Hartgerink et al. (2001). Copyright 2001 American Association for the Advancement of Science.

Five years after the discovery of fullerenes, Iijima reported in 19911 a novel form of organized carbon which consists of hollow cylindrical structures, a few nanometers in diameter and some micrometers long. Although hollow carbon nanofibers had been prepared for several decades, their walls had never been resolved by High-Resolution Transmission Electron Microscopy (HRTEM). These HRTEM images allowed Iijima to conclude that the walls of the so-called multi-walled carbon nanotubes (MWCNTs) are made up of several concentric cylinders, each being formed by a graphene sheet rolled... 

Fig. 2 Shape and structure of BC. a molecular cellulose chain, b scanning electron microscopy (SEM) of freeze-dried nanofiber network (magnification 10000), c pellicle of bacterial nanocellulose from common static culture...

These results suggest that the use of nanofiber electrodes in a microreactor environment to generate solvated electrons for chemical synthesis, may offer an interesting new route for reduction reactions. We are currently working on this concept in our laboratory (Agiral et al., 2010). 

Abstract. A chemical composition and structural parameters of specially prepared catalyst for the pyrolytic synthesis of carbon nanomaterials have been studied by X-ray diffraction, Mossbauer spectroscopy and electron microscopy. A plenty of chemical transformations in the catalyst have been monitored. The inert (Mgi xFxO) and active, very fine particles of the catalyst (MgFe204) components which are involved in the process of carbon nanofibers were revealed. 

Surface area of as-obtained CNF is nearly 300-500 m2/g. One of the effective methods of activation of different carbon materials is treatment with melted KOH at 400-900°C. High surface area (up to nearly 3000 m2/g) carbon materials were obtained [16, 17]. This method was also applied to carbon nanotubes. Significant development of surface was observed, from 465 m2/g for starting MWNT to 1184 m2/g after activation [18], Also, KOH activation of carbon nanofibers resulted in increase of surface area from initial 174 m2/g up to 1212 m2/g [19]. When activated our nanofibers, we obtained for some samples very high effective surface area, nearly 2000-4000 m2/g and in some experiments even 6000 m2/g (measured by argon desorption method). In electron image of activated material (Fig. 7) fiber-like structure is observed. 

Electronic Components Basic Specialty Chemicals Ceramic Materials Carbon Nanofiber Graphite... 

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