• Title, Summary, Keyword: carbon nanowires

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Caffeine as a source for nitrogen doped graphene, and its functionalization with silver nanowires in-situ

  • Ramirez-Gonzalez, Daniel;Cruz-Rivera, Jose de J.;Tiznado, Hugo;Rodriguez, Angel G.;Guillen-Escamilla, Ivan;Zamudio-Ojeda, Adalberto
    • Advances in nano research
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    • v.9 no.1
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    • pp.25-32
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    • 2020
  • In this work, we report the use of caffeine as an alternative source of nitrogen to successfully dope graphene (quaternary 400.6 eV and pyridinic at 398 eV according XPS), as well as the growth of silver nanowires (in-situ) in the surface of nitrogen doped graphene (NG) sheets. We used the improved graphene oxide method (IGO), chemical reduction of graphene oxide (GOx), and impregnation with caffeine as source of nitrogen for doping and subsequently, silver nanowires (NW) grow in the surface by the reduction of silver salts in the presence of NG, achieving a numerous of growth of NW in the graphene sheets. As supporting experimental evidence, the samples were analyzed using conventional characterization techniques: SEM-EDX, XRD, FT-IR, micro RAMAN, TEM, and XPS.

3D Hierarchical Heterostructure of TiO2 Nanorod/Carbon Layer/NiMn-Layered Double Hydroxide Nanosheet

  • Zhao, Wei;Jung, Hyunsung
    • Journal of the Korean institute of surface engineering
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    • v.51 no.6
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    • pp.365-371
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    • 2018
  • 1D core-shell nanostructures have attracted great attention due to their enhanced physical and chemical properties. Specifically, oriented single-crystalline $TiO_2$ nanorods or nanowires on a transparent conductive substrate would be more desirable as the building core backbone. However, a facile approach to produce such structure-based hybrids is highly demanded. In this study, a three-step hydrothermal method was developed to grow NiMn-layered double hydroxide-decorated $TiO_2$/carbon core-shell nanorod arrays on transparent conductive fluorine-doped tin oxide (FTO) substrates. XRD, SEM, TEM, XPS and Raman were used to analyze the obtained samples. The in-situ fabricated hybrid nanostructured materials are expected to be applicable for photoelectrode working in water splitting.

One-dimensional Nanomaterials for Field Effect Transistor (FET) Type Biosensor Applications

  • Lee, Min-Gun;Lucero, Antonio;Kim, Ji-Young
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.4
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    • pp.165-170
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    • 2012
  • One-dimensional, nanomaterial field effect transistors (FET) are promising sensors for bio-molecule detection applications. In this paper, we review fabrication and characteristics of 1-D nanomaterial FET type biosensors. Materials such as single wall carbon nanotubes, Si nanowires, metal oxide nanowires and nanotubes, and conducting polymer nanowires have been widely investigated for biosensors, because of their high sensitivity to bio-substances, with some capable of detecting a single biomolecule. In particular, we focus on three important aspects of biosensors: alignment of nanomaterials for biosensors, surface modification of the nanostructures, and electrical detection mechanism of the 1-D nanomaterial sensors.

Synthesis and Characterization of SnO2-CoO/carbon-coated CoO Core/shell Nanowire Composites (SnO2-CoO/carbon-coated CoO core/shell 나노선 복합체의 합성 및 구조분석)

  • Lee, Yu-Jin;Koo, Bon-Ryul;Ahn, Hyo-Jin
    • Journal of Korean Powder Metallurgy Institute
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    • v.21 no.5
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    • pp.360-365
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    • 2014
  • $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites were synthesized by using electrospinning and hydrothermal methods. In order to obtain $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites, $SnO_2-Co_3O_4$ nanowire composites and $SnO_2-Co_3O_4$/polygonal $Co_3O_4$ core/shell nanowire composites are also synthesized. To demonstrate their structural, chemical bonding, and morphological properties, field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were carried out. These results indicated that the morphologies and structures of the samples were changed from $SnO_2-Co_3O_4$ nanowires having cylindrical structures to $SnO_2-Co_3O_4/Co_3O_4$ core/shell nanowires having polygonal structures after a hydrothermal process. At last, $SnO_2-CoO$/carbon-coated CoO core/shell nanowire composites having irregular and high surface area are formed after carbon coating using a polypyrrole (PPy). Also, there occur phases transformation of cobalt phases from $Co_3O_4$ to CoO during carbon coating using a PPy under a argon atmosphere.

Emission Stability of Semiconductor Nanowires (반도체 나노와이어에서 전자방출 안정성)

  • Yu, Se-Gi;Jeong, Tae-Won;Lee, Sang-Hyun;Heo, Jung-Na;Lee, Jeong-Hee;Lee, Cheol-Jin;Kim, Jin-Young;Lee, Hyung-Sook;Kuk, Yoon-Pil;Kim, J.M.
    • Journal of the Korean Vacuum Society
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    • v.15 no.5
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    • pp.499-505
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    • 2006
  • Field emission of GaN and GaP nanowires, synthesized by thermal chemical vapor deposition, and their emission stabilities under oxygen and argon environments were investigated. The field emission current of GaN nanowires was seriously deteriorated under oxygen environment, while that of GaP was not. Both wires did not show any noticeable change under argon environment. The existence of oxide outer shell layers in the GaP nanowires was proposed to be a main reason for this emission stability behavior. Field emission energy distributions of electrons from these nanowires revealed that field emission mechanism of the semiconductor nanowires were different from that of carbon nanotubes.

Synthesis of TiO2 Nanowires by Metallorganic Chemical Vapor Deposition (유기금속 화학기상증착법을 이용한 TiO2 나노선 제조)

  • Heo, Hun-Hoe;Nguyen, Thi Quynh Hoa;Lim, Jae-Kyun;Kim, Gil-Moo;Kim, Eui-Tae
    • Korean Journal of Materials Research
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    • v.20 no.12
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    • pp.686-690
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    • 2010
  • $TiO_2$ nanowires were self-catalytically synthesized on bare Si(100) substrates using metallorganic chemical vapor deposition. The nanowire formation was critically affected by growth temperature. The $TiO_2$ nanowires were grown at a high density on Si(100) at $510^{\circ}C$, which is near the complete decomposition temperature ($527^{\circ}C$) of the Ti precursor $(Ti(O-iPr)_2(dpm)_2)$. At $470^{\circ}C$, only very thin (< $0.1{\mu}m$) $TiO_2$ film was formed because the Ti precursor was not completely decomposed. When growth temperature was increased to $550^{\circ}C$ and $670^{\circ}C$, the nanowire formation was also significantly suppressed. A vaporsolid (V-S) growth mechanism excluding a liquid phase appeared to control the nanowire formation. The $TiO_2$ nanowire growth seemed to be activated by carbon, which was supplied by decomposition of the Ti precursor. The $TiO_2$ nanowire density was increased with increased growth pressure in the range of 1.2 to 10 torr. In addition, the nanowire formation was enhanced by using Au and Pt catalysts, which seem to act as catalysts for oxidation. The nanowires consisted of well-aligned ~20-30 nm size rutile and anatase nanocrystallines. This MOCVD synthesis technique is unique and efficient to self-catalytically grow $TiO_2$ nanowires, which hold significant promise for various photocatalysis and solar cell applications.

Fabrication of a Resonator using suspended Multi-wall Carbon Nanotubes (다중벽 탄소나노튜브를 이용한 공진기 제작)

  • Lee J.H.;Seo H.W.;Song J.W.;Han C.S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.465-466
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    • 2006
  • A single-wall carbon nanotube (SWCNT) has been studied as a material of Nano-Eletro-Mechanical-System (NEMS) device together with various nanowires. In order for oscillation of a multi-wall carbon nanotube (MWCNT) or a single-walled carbon nanotube (SWCNT) on plane surface, it needs suspension of a CNT across trench electrodes. So we propose fabrication method of a MWCNT resonator using dielectrophoresis and show successful results of suspeneded MWNT. Thin electrodes with large gaps could not suspend small diameter MWNT but thicker electrodes could. Thin MWNT could be suspended only when the electrode gap was reduced.

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Structural Phases of Potassium Intercalated into Carbon Nanotubes (탄소 나노튜브 내부에 삽입된 칼륨 구조)

  • 변기량;강정원;송기오;최원영;황호정
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.249-258
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    • 2004
  • We investigated structural phases of potassium intercalated into carbon nanotubes using a structural optimization process applied to atomistic simulation methods. As the radius of carbon nanotubes increased, structures were found in various phases from an atomistic strand to multishell packs composed of coaxial cylindrical shells and in helical, layed, and crystalline structures. Numbers of helical atom rows composed of coaxial tubes and orthogonal vectors of a circular rolling of a triangular network could explain multishell phases of potassium in carbon nanotubes.