Table of content

OAtube Nanotechnology

ISSN/EISSN: 19341490
Subject: Technology (General)
Publisher: Open Access House of Science and Technology
Country: United States
Language: English
Start year 2008
Publication fee: No --- Further Information

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Table of content: 2008 volume:1 issue:2

Article
Carbon nanotubes: optimized growth for applications and practical use of large CNT structures

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Abstract

Carbon nanotubes attracted large-scale scientific interest and their properties are well-studied for the cases when theoretical model work, and at the same time growth routes and proof of the concept applications were demonstrated (see e.g. Ref. 1). In this talk I briefly summarize our latest result on the most important parameters of multiwalled carbon nanotube growth via the floating catalyst Ferrocene-Xylene route applied earlier with success to create large CNT structures [2]. We investigated the kinetics [3] of the process both experimentally and theoretically and optimized the parameters for carbon nanotube length and also for their quality. These studies were used to reach macroscopic carbon nanotube structures with unique properties optimized to use them as synergistic units. In the main part of the talk I focus on characterization of the structures and their recent applications. Aligned carbon nanotube forests grown with different methods showed wide range of density depending on growth parameters; the physical properties of these films, e.g. compressibility, optical absorbance, thermal and electrical conductivity are unparalleled. To demonstrate the usefulness of these properties I will cite laboratory level applications. First a chip cooler setup [4], made of aligned multiwalled carbon nanotube forest will be presented, where the cooling performance of the device is comparable to a copper cooler having similar geometry; however, the carbon nanotube cooler is much lighter, mechanically stronger and it has more potential for further optimization. Another family of application is printing carbon nanotubes from different kind of “inks” [5-6]. The most interesting feature of this use is the fact that different coverage of the carbon nanotube film results in either low resistance Ohmic (for high coverage) or a nonlinear (for low coverage) behavior which latter one can be driven by gate voltage [6]. Via controlled amount of materials printed on the multi-micrometer scale the method can prepare complete electronic circuits with active elements and wires made of the same carbon nanotube ink without requiring any expensive pre-selection of semi-conductive and metallic tubes. These applications, together with several other, shortly mentioned ones, outdraw the possibilities that large scale, organized carbon nanotube structures inherently infer.

Keywords

Nanotubes


Article
Multifunctional Hybrid Nanocrystal-Carbon Nanotube Structures

Authors: J.H.Chen
Pages: 1007
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Abstract

Hybrid nanomaterials composed of nanocrystals distributing on the surfaces of carbon nanotubes (CNTs) represent a new class of materials. These materials could potentially display not only the unique properties of nanocrystals and those of CNTs, but also additional novel properties due to the interaction (e.g., electronic or optical) between the nanocrystal and the CNT. Such hybrid nanocrystal-CNT structures are promising for various innovative nanotechnological applications, including chemical sensors [1], biosensors [2], nanoelectronics [3], photovoltaic cells [4], fuel cells [5], and hydrogen storage [6]. In this talk, I will present a material-independent, dry route based on the electrostatic force directed assembly (ESFDA) to assemble aerosol nanocrystals onto CNTs [7-11]. The method takes advantage of the small diameter of CNTs for a significantly enhanced electric field near the CNT surface, which is then used to attract charged aerosol nanocrystals [12] onto oppositely-biased CNTs. The ESFDA technique works for both random CNTs and aligned CNTs without the need for chemical functionalization or other pretreatments of CNTs. There is an intrinsic nanocrystal size selection during the assembly process, which results in a narrower size distribution for nanocrystals on CNTs than that for as-produced nanocrystals. Moreover, the areal density and the actual size distribution of nanocrystals on the CNT can be controlled. The non-covalent attachment of nanocrystals also preserves the intrinsic properties of CNTs [13]. The new method enables in-situ coating of nanotubes with nanocrystals. Due to the inherent material-independence nature of the electrostatic force, various compositions of such nanocrystal-CNT hybrid structures can be produced using this new technique.

Keywords

Nanotubes

Table of content: 2008 volume:1 issue:2