Carbon Nanostructures (carbon + nanostructure)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Selected Abstracts

C60 Nanostructures for Applications in Information Technology,

Oliver Senftleben
Carbon nanostructures,such as nanotubes, fullerenes, or graphene sheets,are studied widely in search of future applications in electronic devices. In our work, we demonstrate the possibility of embedding C60 fullerene molecules into a crystalline silicon matrix to form highly confined carbon- , -layers as well as into an amorphous SiO2 gate stack for possible application as a charge storage device. [source]

The Critical Role of the Underlayer Material and Thickness in Growing Vertically Aligned Carbon Nanotubes and Nanofibers on Metallic Substrates by Chemical Vapor Deposition

Gilbert D. Nessim
Abstract Vertically aligned carbon nanotubes and nanofibers are grown on metallic Ta and Pd underlayers at temperatures below 500,°C. Controlling the size of the grains of the underlayer film is critical because this leads to a more uniform distribution of catalyst dots, which in turn results in vertical alignment of the carbon nanostructures. Rapid and limited heating and appropriate materials selection can also be used to limit catalyst/underlayer reactions that hinder or suppress carbon nanostructure growth or that lead to entangled growth. Control of catalyst reactivity with metallic underlayers is significant because growth on conductive substrates is notoriously difficult, but needed for many applications such as the use of carbon nanostructures in microelectronic circuits. [source]

Ionic Liquids as Precursors for Nitrogen-Doped Graphitic Carbon

Jens Peter Paraknowitsch
Nitrogen-doped carbons are prepared by thermolysis of two organic, nitrogen-rich ionic liquids (see figure). The nitrogen content can be adjusted by the thermolysis temperature. As the precursors are liquids at room temperature they represent ideal precursors for the direct synthesis of carbon nanostructures and coatings with flexible geometry controlled by the processing of liquids. [source]

Carbon-Based Field-Effect Transistors for Nanoelectronics

ADVANCED MATERIALS, Issue 25-26 2009
Marko Burghard
Abstract In this review, the suitability of the major types of carbon nanostructures as conducting channels of field-effect transistors (FETs) is compared on the basis of the dimensionality and size of their ,-conjugated system. For each of these materials, recent progress in its synthesis, electrical and structural characterization, as well as its implementation into various gate configurations is surveyed, with emphasis laid onto nanoscale aspects of the FET design and the attainable device performance. Finally, promising future research directions, such as the integration of different carbon nanostructures into novel device architectures, are outlined. [source]

Rational Functionalization of Carbon Nanotubes Leading to Electrochemical Devices with Striking Applications,

Jie Yan
Abstract As one-dimensional carbon nanostructures, carbon nanotubes (CNTs) are a member of the carbon family but they possess very different structural and electronic properties from other kinds of carbon materials frequently used in electrochemistry, such as glassy carbon, graphite, and diamond. Although the past decade has witnessed rapid and substantial progress in both the fundamental understanding of CNT-oriented electrochemistry and the development of various kinds of electrochemical devices with carbon nanotubes, the increasing demand from both academia and industry requires CNT-based electrochemical devices with vastly improved properties, such as good reliability and durability, and high performance. As we outline here, the smart functionalization of CNTs and effective methods for the preparation of devices would pave the way to CNT-based electronic devices with striking applications. [source]

A molecular dynamics simulation of air adsorption in single-walled carbon nanotube bundles

Víctor Rojas Cervellera
Abstract The physisorption of air in single-walled carbon nanotubes (SWNTs) is studied employing molecular dynamics. The effect of the nanotube diameter in the gas adsorption capacity of SWNT bundles has been investigated using (10,0), (15,0), and (20,0) SWNTs finding an increasing load capacity. The O2:N2 ratio in the nanotube bundles is analyzed in detail as well, comparing it to that in the gaseous bulk. The air contained in the carbon nanostructures has a larger content in O2 than the bulk air, thus providing a possible application of carbon nanotubes as molecular filters. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source]

Computation of STM images of carbon nanotubes

P. Lambin
Abstract Scanning tunneling microscopy (STM) is the only probing technique that allows for the investigation of both the topography and the electronic structure of carbon nanosystems at a subnanometer resolution. The interpretation of the STM images of carbon nanostructures involves complications that are normally absent in the study of planar crystalline surfaces. The complications typically appear from a number of quantum effects responsible for distortions in the microscope image of a nano-object. Because of these difficulties, computer simulation plays an extremely important role in the analysis of experimental data. In the current article, we report on two theoretical approaches developed for aiding in the interpretation and understanding of the formation of the STM image of a nanotube: first, the quantum mechanical dynamics of a wave packet, which allows for the modeling of the flow of the tunneling current between a tip and a nanotube supported by a substrate; and, second, a tight-binding perturbation theory that allows for the explicit calculation of realistic STM images and scanning tunneling spectra of carbon nanostructures. An atlas of computed STM images is provided for a series of 27 single-wall nanotubes with diameter around 1.3 nm. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 [source]

Formation of carbon nanostructures and spatial-energy stabilization criterion

G. A. Korablev
Abstract A spatial-energy criterion of structure stabilization is obtained. The computational results for 100 binary systems correspond to the experimental data. The basic regularity of organic cyclic compound formation is given and its application for carbon nanostructures is shown. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

Water-Soluble Carbon Nanotubes by Redox Radical Polymerization

Dimitrios Tasis
Abstract Water-soluble single- and multi-walled carbon nanotubes (CNTs) were prepared by grafting polyacrylamide chains from the graphitic surface via ceric ion-induced redox radical polymerization. The reducing functionalities were covalently attached to the tubes by peroxide-assisted radical reaction. The results showed that polymer chains were grafted onto CNTs by the redox process. The redox radical polymerization initiated by carbon nanotube-bearing functionalities not only provides a powerful strategy for modifying the carbon nanostructures but also gives us the knowledge of their sidewall chemistry. [source]

On the use of Cu catalysts for tailoring carbon nanostructures in alcohol-CVD

Ewa Borowiak-Palen
Abstract The use of the alcohol-chemical vapor deposition (A-CVD) process applying ferromagnetic catalyst mixes is a powerful technique for the synthesis of high purity single-, double- and multiwalled carbon nanotubes (MWCNTs). Here, we report on a systematic experimental study on the preparation route of carbon nanofibres (CNFs), bamboo-like carbon nanotubes (BMCNTs) with defined pocket size and mean diameter and MWCNTs. Copper serves as the catalyst. The morphology of the samples is controlled by the reaction temperature and the catalyst loading relative to the support content (MgO). A detailed analysis of the samples was achieved by electron transmission microscopy observations and Raman spectroscopy. Schematic illustration showing the carbon nanostructure evolution with increasing reaction temperature. [source]

Microwave-Assisted Functionalization of Carbon Nanostructures in Ionic Liquids

Ivan Guryanov Dr.
Abstract The effect of microwave (MW) irradiation and ionic liquids (IL) on the cycloaddition of azomethine ylides to [60]fullerene has been investigated by screening the reaction protocol with regard to the IL medium composition, the applied MW power, and the simultaneous cooling of the system. [60]Fullerene conversion up to 98,% is achieved in 2,10,min, by using a 1:3 mixture of the IL 1-methyl-3- n -octyl imidazolium tetrafluoroborate ([omim]BF4) and o -dichlorobenzene, and an applied power as low as 12,W. The mono- versus poly-addition selectivity to [60]fullerene can be tuned as a function of fullerene concentration. The reaction scope includes aliphatic, aromatic, and fluorous-tagged (FT) derivatives. MW irradiation of IL-structured bucky gels is instrumental for the functionalization of single-walled carbon nanotubes (SWNTs), yielding group coverages of up to one functional group per 60 carbon atoms of the SWNT network. An improved performance is obtained in low viscosity bucky gels, in the order [bmim]BF4> [omim]BF4> [hvim]TF2N (bmim=1-methyl-3- n -butyl imidazolium; hvim=1-vinyl-3- n -hexadecyl imidazolium). With this protocol, the introduction of fluorous-tagged pyrrolidine moieties onto the SWNT surface (1/108 functional coverage) yields novel FT-CNS (carbon nanostructures) with high affinity for fluorinated phases. [source]

DFT/CCSD(T) Investigation of the Interaction of Molecular Hydrogen with Carbon Nanostructures

CHEMPHYSCHEM, Issue 11 2009
Miroslav Rube
Abstract The interaction of molecular hydrogen with carbon nanostructures is investigated within the DFT/CC correction scheme. The DFT/CC results are compared with the benchmark calculations at the CCSD(T) level of theory for benzene and naphthalene, and at the MP2 level for the more extended systems. The DFT/CC method offers a reliable alternative to the highly correlated ab initio calculations at a cost comparable to the standard DFT method. The results for H2 adsorbed on graphene as well as single-wall carbon nanotubes (SWCNT) are presented. The DFT/CC binding energy on graphene of 5.4 kJ,mol,1 is in good agreement with experiment (5.00±0.05 kJ,mol,1). For (10,10)-SWCNT, the H2 molecule is mostly stabilized inside the tube with an estimated binding energy of 7.2 kJ,mol,1. [source]