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Double-walled carbon nanotubes: synthesis, structural characterization, and application
Kim, Yoong Ahm,Yang, Kap-Seung,Muramatsu, Hiroyuki,Hayashi, Takuya,Endo, Morinobu,Terrones, Mauricio,Dresselhaus, Mildred S. 한국탄소학회 2014 Carbon Letters Vol.15 No.2
Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.
Kim, Yoong Ahm,Aoki, Shunta,Fujisawa, Kazunori,Ko, Yong-Il,Yang, Kap-Seung,Yang, Cheol-Min,Jung, Yong Chae,Hayashi, Takuya,Endo, Morinobu,Terrones, Mauricio,Dresselhaus, Mildred S. American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.8
<P>Carbon nanotubes have shown great potential as conductive fillers in various composites, macro-assembled fibers, and transparent conductive films due to their superior electrical conductivity. Here, we present an effective defect engineering strategy for improving the intrinsic electrical conductivity of nanotube assemblies by thermally incorporating a large number of boron atoms into substitutional positions within the hexagonal framework of the tubes. It was confirmed that the defects introduced after vacuum ultraviolet and nitrogen plasma treatments facilitate the incorporation of a large number of boron atoms (ca. 0.496 atomic %) occupying the trigonal sites on the tube sidewalls during the boron doping process, thus eventually increasing the electrical conductivity of the carbon nanotube film. Our approach provides a potential solution for the industrial use of macro-structured nanotube assemblies, where properties, such as high electrical conductance, high transparency, and lightweight, are extremely important.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-8/jp410732r/production/images/medium/jp-2013-10732r_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp410732r'>ACS Electronic Supporting Info</A></P>
Carbon Nanotubes: State-of-the-art Technology and Safety for Success
Morinobu Endo,Yoong-Ahm Kim,Takuya Hayashi 한국탄소학회 2009 Carbon Letters Vol.10 No.2
Carbon nanotubes, consisting of rolled graphene layer built from sp2 units, have attracted the imagination of scientists as ideal macromolecules and their unusual physical and chemical properties make them useful in the fabrication of nanocomposites, nano-electronic devices and sensors etc. In this account, the current status and prospect of carbon nanotubes is described with a special emphasis on the safety issue of carbon nanotubes. Even though many challenges to be solved remain, extensive and intensive efforts in both academy and industry will clear out those problems soon and finally enable carbon nanotubes to play a key innovative material of 21st century in numerous industrial processes.
Pore engineering of nanoporous carbon nanofibers toward enhanced supercapacitor performance
Kim, Chang Hyo,Yang, Cheol-Min,Kim, Yoong Ahm,Yang, Kap Seung Elsevier BV * North-Holland 2019 Applied Surface Science Vol.497 No.-
<P><B>Abstract</B></P> <P>Porous carbon nanofibers (PCNFs) were prepared from electrospinning both without and with a pore generating inorganic material. Next, they were activated with different activation media (N<SUB>2</SUB>, H<SUB>2</SUB>O, or CO<SUB>2</SUB>). The pore size was tailored from 0.64 to 0.81 nm under various activation conditions, and the specific surface area ranged from 404 to 1624 m<SUP>2</SUP>·g<SUP>−1</SUP>. To determine the charging mechanism of the supercapacitor in an aqueous electrolyte, the normalized capacitance was calculated, and it was compared with the adsorption behavior of the solvent, H<SUB>2</SUB>O, separately. The normalized capacitance showed a trend similar to that of H<SUB>2</SUB>O adsorption at a low relative pressure (<I>P</I>/<I>P</I> <SUB> <I>0</I> </SUB> = 0.1), which was expected to be driven by the filler–pore wall interaction, indicating that the ions were strongly solvated by the solvent, H<SUB>2</SUB>O. The highest normalized capacitance value (32 μF·cm<SUP>−2</SUP> at 1 mA·cm<SUP>−2</SUP>) was achieved from PCNFs having a pore size of 0.64 nm, similar to the electrolyte solvated ion sizes. It was observed that both the capacitance and H<SUB>2</SUB>O adsorption were achieved near the pore size of 0.64 nm and at a high functionality. It was understood that the adsorption of the solvated ions was primarily driven by the interaction of the solvent, H<SUB>2</SUB>O, with the surface functional groups.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Finely tuned porous carbon nanofibers (PCNFs) with pore size of 0.64–0.81 nm are prepared. </LI> <LI> Capacitive behavior and H<SUB>2</SUB>O adsorption property of the PCNFs are evaluated. </LI> <LI> High normalized capacitance is achieved from pore size similar to solvated ion sizes. </LI> <LI> Suitable pore size and high surface functionality are key factors for supercapacitor application. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Jung, Yong Chae,Yoo, Hye Jin,Kim, Yoong Ahm,Cho, Jae Whan,Endo, Morinobu Elsevier 2010 Carbon Vol.48 No.5
<P><B>Abstract</B></P><P>The electroactive shape memory of carbon nanotube-filled polyurethane composites, prepared by conventional blending, <I>in situ</I> and cross-linking polymerization, is studied in terms of the dispersion of the tubes. The covalently bonded tubes are homogeneously dispersed within the polyurethane by introducing carboxyl groups on the sidewall of the tubes and selecting a cross-linking polymerization method. The resultant composites, which have 92% shape retention and 95% shape recovery, are expected to be used as preferential materials in various actuators.</P>
Single-walled carbon nanotubes directly-grown from orientated carbon nanorings
Tomohiro Tojo,Ryoji Inada,Yoji Sakurai,Yoong Ahm Kim 한국탄소학회 2018 Carbon Letters Vol.27 No.-
Surfactant-wrapped separation methods of metallic and semiconducting single-walled carbon nanotubes(SWCNTs) can result in large changes in intrinsic physical and chemical properties due to electronic interactions between a nanotube and a surfactant. Our approach to synthesize SWCNTs with an electronic feature relied on utilizing carbon nanorings, [n] cycloparaphenylenes([n]CPPs), which are the fundamental unit of armchair type SWCNTs(a-SWCNTs) that possess a metallic feature without any surfactants. To obtain long tubular structures from [n]CPPs, the host-guest complexes formed with well-aligned [n]CPP hosts and various fullerene guests on a silicon substrate were pyrolyzed under an ethanol gas flow at a high temperature with focused-ultraviolet laser irradiation. The pyrolyzed [n]CPPs were observed to transform from nanorings to tubular structures with 1.5–1.7 nm diameters corresponding to the employed diameter of [n]CPPs. Our approach suggests that [n]CPPs are useful for structure-controlled synthesis of SWCNTs.
Tomohiro Tojo,Cheon Soo Kang,Takuya Hayashi,Yoong Ahm Kim 한국탄소학회 2018 Carbon Letters Vol.28 No.-
Linear carbon chains (LCCs) encapsulated inside the hollow cores of carbon nanotubes (CNTs) have been experimentally synthesized and structurally characterized by Raman spectroscopy and transmission electron microscopy. However, in terms of electronic conductivity, their transportation mechanism has not been investigated theoretically or experimentally. In this study, the density of states and quantum conductance spectra were simulated through density functional theory combined with the non-equilibrium Green function method. The encapsulated LCCs inside (5,5), (6,4), and (9,0) single-walled carbon nanotubes (SWCNTs) exhibited a drastic change from metallic to semiconducting or from semiconducting to metallic due to the strong charge transfer between them. On the other hand, the electronic change in the conductance value of LCCs encapsulated inside the (7,4) SWCNT were in good agreement with the superposition of the individual SWCNTs and the isolated LCCs owing to the weak charge transfer.