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pISSN : 1976-4251 / eISSN : 2233-4998

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2013, Vol.14, No.3

  • 1.

    Carbon nanotubes–properties and applications: a review

    Khalid Saeed Ibrahim | 2013, 14(3) | pp.131~144 | number of Cited : 9
    Abstract
    The carbon nanotube (CNT) represents one of the most unique inventions in the field of nanotechnology. CNTs have been studied closely over the last two decades by many researchers around the world due to their great potential in different fields. CNTs are rolled graphene with SP2 hybridization. The important aspects of CNTs are their light weight, small size with a high aspect ratio, good tensile strength, and good conducting characteristics, which make them useful as fillers in different materials such as polymers, metallic surfaces and ceramics. CNTs also have potential applications in the field of nanotechnology, nanomedicine, transistors,actuators, sensors, membranes, and capacitors. There are various techniques which can be used for the synthesis of CNTs. These include the arc-discharge method, chemical vaporize deposition (CVD), the laser ablation method, and the sol gel method. CNTs can be single-walled, double-walled and multi-walled. CNTs have unique mechanical, electrical and optical properties, all of which have been extensively studied. The present review is focused on the synthesis, functionalization, properties and applications of CNTs. The toxic effect of CNTs is also presented in a summarized form.
  • 2.

    Graphene growth from polymers

    서홍규 | 이태우 | 2013, 14(3) | pp.145~151 | number of Cited : 0
    Abstract
    Graphene is a fascinating material with excellent electrical, optical, mechanical, and chemical properties. Remarkable progress has been made in the development of methods for synthesizing large-area, high-quality graphene. Recently, the chemical vapor deposition method has opened up the possibility of using graphene for electronic devices and other applications. This review covers simple and inexpensive methods to grow graphene using polymers as solid carbon sources; which do not require an additional process to transfer graphene from the growth substrate to the receiver substrate.
  • 3.

    Preparation of needle coke from petroleum by-products

    Humala Paulus Halim | Im Ji Sun | Chul Wee Lee | 2013, 14(3) | pp.152~161 | number of Cited : 3
    Abstract
    Needle coke is an important material for graphite electrodes. Delayed coking is used to produce needle coke. Producing good quality needle coke is not simple because it is a multi-parameter controlled process. Apart from that, it is important to understand the mechanism responsible for the delayed coking process, which involves mesophase formation and uniaxial rearrangement. Temperature and pressure need to be optimized for the different substances in every feedstock. Saturate hydrocarbon, aromatic, resin and asphaltene compounds are the main components in the delayed coking process for a low Coefficient Thermal Expansion value. In addition, heteroatoms, such as sulphur, oxygen, nitrogen and metal impurities, must be considered for a better graphitization process that prevents the puffing effect and produces better mesophase formation.
  • 4.

    Contact resistance in graphene channel transistors

    송성민 | 조병진 | 2013, 14(3) | pp.162~170 | number of Cited : 0
    Abstract
    The performance of graphene-based electronic devices is critically affected by the quality of the graphene-metal contact. The understanding of graphene-metal is therefore critical for the successful development of graphene-based electronic devices, especially field-effect-transistors. Here, we provide a review of the peculiar properties of graphene-metal contacts, including work function pinning, the charge transport mechanism, the impact of the process on the contract resistance, and other factors.
  • 5.

    Reduction of metal-graphene contact resistance by direct growth of graphene over metal

    홍슬기 | 송승민 | Onejae Sul and 1other persons | 2013, 14(3) | pp.171~174 | number of Cited : 1
    Abstract
    The high quality contact between graphene and the metal electrode is a crucial factor in achieving the high performance of graphene transistors. However, there is not sufficient research about contact resistance reduction methods to improve the junction of metal-graphene. In this paper, we propose a new method to decrease the contact resistance between graphene and metal using directly grown graphene over a metal surface. The study found that the grown graphene over copper, as an intermediate layer between the copper and the transferred graphene, reduces contact resistance, and that the adhesion strength between graphene and metal becomes stronger. The results confirmed the contact resistance of the metalgraphene of the proposed structure is nearly half that of the conventional contact structure.
  • 6.

    Micro-Raman characterization of isolated single wall carbon nanotubes synthesized using Xylene

    최영철 | 2013, 14(3) | pp.175~179 | number of Cited : 2
    Abstract
    Isolated single wall carbon nanotubes (SWCNTs) were synthesized by chemical vapor deposition (CVD) using a liquid precursor (xylene) as a carbon source. Transmission electron microscopy (TEM) and atomic force microscopy confirmed the isolated structure of the SWCNTs. Micro-Raman measurements showed a tangential G-band peak (1590 cm-1) and radial breathing mode (RBM) peaks (150-240 cm-1). The tube diameters determined from the RBM frequencies are in good agreement with those obtained from TEM. The chirality of the isolated SWCNTs could be determined based on the energy of the laser and their diameter. A further preliminary study on the nitrogen doping of isolated SWCNTs was carried out by the simple use of acetonitrile dissolved in the precusor.
  • 7.

    Comparative studies of porous carbon nanofibers by various activation methods

    이혜민 | Kim Hong-Gun | 강효랑 and 2other persons | 2013, 14(3) | pp.180~185 | number of Cited : 8
    Abstract
    In this study, activated carbons nanofibers (ACNFs) were prepared from polyacrylonitrile-based nanofibers by physical (H2O and CO2) and chemical (KOH) activation. The surface and structural characteristics of the porous carbon were observed by scanning electron microscopy and X-ray diffraction, respectively. Pore characteristics were investigated by N2/77K adsorption isotherms. The specific surface area of the physically ACNFs was increased up to 2400 m2/g and the ACNFs were found to be mainly composed of micropore structures. Chemical activation using KOH produced ACNFs with high specific surface area (up to 2500 m2/g), and the micropores were mainly found in the ACNFs. The physically and chemically ACNFs showed both mainly type I from the International Union of Pure and Applied Chemistry classification.
  • 8.

    Flexible NO2 gas sensor using multilayer graphene films by chemical vapor deposition

    최홍주 | Jeong Hu Young | Dae-Sik Lee and 2other persons | 2013, 14(3) | pp.186~189 | number of Cited : 1
    Abstract
    We report a highly sensitive NO2 gas sensor based on multi-layer graphene (MLG) films synthesized by a chemical vapor deposition method on a microheater-embedded flexible substrate. The MLG could detect low-concentration NO2 even at sub-ppm (<200 ppb) levels. It also exhibited a high resistance change of ~6% when it was exposed to 1 ppm NO2 gas at room temperature for 1 min. The exceptionally high sensitivity could be attributed to the large number of NO2 molecule adsorption sites on the MLG due to its a large surface area and various defect-sites, and to the high mobility of carriers transferred between the MLG films and the adsorbed gas molecules. Although desorption of the NO2 molecules was slow, it could be enhanced by an additional annealing process using an embedded Au microheater. The outstanding mechanical flexibility of the graphene film ensures the stable sensing response of the device under extreme bending stress. Our large-scale and easily reproducible MLG films can provide a proof-of-concept for future flexible NO2 gas sensor devices.
  • 9.

    A study on the fracture toughness of seawater-absorbed carbon nanotube/epoxy/basalt composites

    김만태 | Rhee Kyong Yop | 김현주 and 1other persons | 2013, 14(3) | pp.190~192 | number of Cited : 1
    Abstract
    It has been demonstrated in a previous study that carbon nanotube (CNT)/epoxy/basalt composites produce better flexural properties than epoxy/basalt composites. In this study, mode І fracture tests were conducted using CNT/epoxy/basalt composites with and without seawater absorption in order to investigate the effect of the seawater absorption on the mode I fracture toughness (GIc) of the CNT/epoxy/basalt composites. The results demonstrated that the compliance of the seawater-absorbed specimen was larger than that of the dry specimen at the same crack length, while the opposite result was obtained for the fracture load. The GIc value of the seawater-absorbed CNT/epoxy/basalt composites was approximately 20% lower than that of the dry CNT/epoxy/basalt composites.
  • 10.

    A novel drying process for oil adsorption of expanded graphite

    PARK SOOJIN | 이슬이 | Kisug Kim and 1other persons | 2013, 14(3) | pp.193~195 | number of Cited : 2
    Abstract
    Expanded graphite (EG) was prepared using a drying process for application as an oiladsorbent:the morphology, expansion volume, and oil absorption capacity of the EG were investigated. The expanded volume of the EG increased with an increasing reaction time and heat treatment temperature. The oil adsorption capacity of the EG was 45 g of n-dodecane per 1 g of EG. It is noted that the drying process of EG is a useful technique for a new oiladsorbent.