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FABRICATION OF GAS SENSOR USING SINGLE-WALLED CARBON NANOTUBES DISPERSED IN DICHLOROETHANE
KAY HYEOK AN,CHANG SOO HAN,SEUNG YOL JEONG,YOUNG HEE LEE,KI KANG KIM,MIN HEE YUN,HA RYONG HWANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.3
The single-walled carbon nanotube (SWCNT)-field effect transistor (FET) gas sensor was fabricated by spin-coating SWCNTs dispersed in dichloroethane (DCE) solvent on silicon substrate. Raman spectra revealed that walls of the nanotubes were well preserved without much damage during DCE treatment. The sensitivity of the gas sensor was strongly dependent on the series resistance. The sensitivity was maximized in the reasonable contact resistance between nanotubes and electrodes. This was attributed to the suppression of the dark current. The SWCNT gas sensor revealed typical p-type characteristics with respect to NO2 and NH3 gases. The small-bundled SWCNTs increased accessibility of gases to nanotubes and therefore increased the sensitivity of the nanotube gas sensor. The response time was shortened particularly in the case of NO2 gas compared to the previous report.
Elemental Mercury Adsorption Behaviors of Chemically Modified Activated Carbons
김병주,배경민,Kay-Hyeok An,박수진 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.4
In this work, the effects of different surface functional groups on the elemental mercury adsorption of porous carbons modified by chemical treatments were investigated. The surface properties of the treated carbons were observed by Boehm’s titration and X-ray photoelectron spectroscopy (XPS). It was found that the textural properties, including specific surface area and pore structures, slightly decreased after the treatments, while the oxygen content of the ACs was predominantly enhanced. Elemental mercury adsorption behaviors of the acidtreated ACs were found to be four or three times better than those of non-treated ACs or base-treated ACs,respectively. This result indicates that the different compositions of surface functional groups can lead to the high elemental mercury adsorption capacity of the ACs. In case of the acid-treated ACs, the R_(C=O)/R_(C-O) and R_(COOH)/R_(C-O) showed higher values than those of other samples, indicating that there is a considerable relationship between mercury adsorption and surface functional groups on the ACs.
Lee, Hye-Min,An, Kay-Hyeok,Kim, Byung-Joo 한국탄소학회 2014 Carbon Letters Vol.15 No.2
In this work, activated carbon nanofiber(ACNF) electrodes with high double-layer capaci-tance and good rate capability were prepared from polyacrylonitrile nanofibersby optimiz-ing the carbonization temperature prior to H2O activation. The morphology of the ACNFs was observed by scanning electron microscopy. The elemental composition was determined by analysis of X-ray photoelectron spectroscopy. N2-adsorption-isotherm characteristics at 77 K were confirmedby Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. ACNFs processed at different carbonization temperatures were applied as electrodes for electrical double-layer capacitors. The experimental results showed that the surface mor-phology of the CNFs was not significantlychanged after the carbonization process, although their diameters gradually decreased with increasing carbonization temperature. It was found that the carbon content in the CNFs could easily be tailored by controlling the carbonization temperature. The specificcapacitance of the prepared ACNFs was enhanced by increasing the carbonization temperature.
Anisotropic electrical conductivity of MWCNT/PAN nanofiber paper
Ra, Eun Ju,An, Kay Hyeok,Kim, Ki Kang,Jeong, Seung Yol,Lee, Young Hee Elsevier 2005 Chemical physics letters Vol.413 No.1
<P><B>Abstract</B></P><P>The electrospinning process has been used successfully to fabricate the multiwalled carbon nanotubes (MWCNTs)-embedded polyacrylonitrile (PAN) nanofiber paper. The diameters of nanofibers decreased with increasing CNT concentration. We found large anisotropic electrical conductivity, i.e., the electrical conductivity of the carbonized nanofiber paper along the spinning direction was about three times larger than that normal to the spinning direction, in good contrast with observations that the carbonized PAN nanofiber paper without CNTs did not reveal anisotropy in electrical conductivity. This proves that CNTs in PAN nanofiber were preferentially aligned along the nanofiber axis, in excellent agreements with transmission electron microscopy observations.</P>
ELECTRONIC-STRUCTURE ENGINEERING OF CARBON NANOTUBES
YOUNG HEE LEE,KAY HYEOK AN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.2
A review for controlling electronic structures and chirality separation of carbon nanotubes (CNTs) is presented with the subject divided into three topics. The first topic introduces the electronic structures of CNTs and the analytical techniques to identify the chirality of CNTs. The second topic discusses band gap engineering techniques using the sidewall functionalization of CNTs. The third topic concerns several approaches in chiral and diameter-dependent separation of CNTs. The electronic-structure engineering is of critical importance for a variety of technological applications of CNTs including, for example, field-effect transistor, chemical/bio-nanosensors, the electrical conductivity and charge dissipation in polymer/CNT composites, and flexible transparent conducting films. This paper is intended to concisely review the recent advances in the experimental and theoretical CNT researches concerned with the band gap engineering and chiral separation techniques of CNTs.
Dong-Kyu Kim,Kay-Hyeok An,Yun Hyuk Bang,Lee-Ku Kwac,Sang-Yub Oh,Byung-Joo Kim 한국탄소학회 2016 Carbon Letters Vol.19 No.-
In this work, we studied the effects of electrochemical oxidation treatments of carbon fibers (CFs) on interfacial adhesion between CF and epoxy resin with various current densities. The surface morphologies and properties of the CFs before and after electrochemical-oxidation-treatment were characterized using field emission scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and single-fiber contact angle. The mechanical interfacial shear strength of the CFs/epoxy matrix composites was investigated by using a micro-bond method. From the results, electrochemical oxidation treatment introduced oxygen functional groups and increased roughness on the fiber surface. The mechanical interfacial adhesion strength also showed higher values than that of an untreated CF-reinforced composite.