• Journal of Powder Materials
• /
• v.24 no.4
• /
• pp.279-284
• /
• 2017

The formation mechanism and photocatalytic properties of a multiwalled carbon nanotube (MWCNT)/$TiO_2$-based nanotube (TNTs) composite are investigated. The CNT/TNT composite is synthesized via a solution chemical route. It is confirmed that this 1-D nanotube composite has a core-shell nanotubular structure, where the TNT surrounds the CNT core. The photocatalytic activity investigated based on the methylene blue degradation test is superior to that of with pure TNT. The CNTs play two important roles in enhancing the photocatalytic activity. One is to act as a template to form the core-shell structure while titanate nanosheets are converted into nanotubes. The other is to act as an electron reservoir that facilitates charge separation and electron transfer from the TNT, thus decreasing the electron-hole recombination efficiency.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.179.2-179.2
• /
• 2014

Carbon nanotubes (CNT)-metal contacts play an important role in nanoelectronics applications such as field-effect transistor (FET) devices. Using Al and (10,0) CNT, we have recently showed that the CNT-metal contacts mediated via topological defects within CNT exhibits intrinsically low contact resistance, thanks to the preservation of the sp2 bonding network at the metal-CNT contacts.[1] It is well-established that metals with good wetting property such as Pd consistently yield good contacts to both metallic and semiconducting CNTs. In this work, the electronic and charge transport properties of the interfaces between capped CNT and Pd will be investigated based on first-principles computations and compared with previous results obtained for the Al electrodes.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.366-367
• /
• 2006

Carbon nanotubes (CNTs) have attracted remarkable attention as reinforcement for composites owing to their outstanding mechanical properties. The CNT/Cu nanocomposite is fabricated by a novel fabrication process named molecular level process. The novel process for fabricating CNT/Cu composite powders involves suspending CNTs in a solvent by surface functionalization, mixing Cu ions with CNT suspension, drying, calcination and reduction. The molecular level process produces CNT/Cu composite powders whereby the CNTs are homogeneously implanted within Cu powders. The mechanical properties of CNT/Cu nanocomposite, consolidated by spark plasma sintering of CNT/Cu composite powders, shows about 3 times higher strength and 2 times higher Young's modulus than those of Cu matrix.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.997-1000
• /
• 2004

This paper introduces our basic research about a carbon nanotube(CNT) sample for the fabrication of nanotweezer. We have made the nanotweezer through the physical adhesion of multi-walled carbon nanotubes(MWCNTs) on two sharp tungsten tips. Thereby we needed the CNT sample which is proper to this fabrication process. And we applied the dielectrophoretic methods to the fabrication of the CNT sample. During the basic experiment, we used a sharp edged electrode and a flat electrode as electrodes for dielectrophoresis and just a function generator as a voltage source for the generation of electric field.

• Journal of Adhesion and Interface
• /
• v.4 no.4
• /
• pp.22-27
• /
• 2003

Chemical modification of carbon nanotube (CNT) was carried out using $HNO_3$ and $H_2SO_4$ and characterized by analyzing the CNT before and after the modification using FT-IR and titration. Aggregation behaviors were investigated using a real-time video microscope after the chemically modified CNT(mCNT) had been dispersed in organic solvents such as toluene, dimethylformamide (DMF) and N-methylpyrrolidone (NMP) by ultrasonication. The mCNT showed better dispersion in polar sovents of DMF and NMP than the rCNT. CNT/ poly(methylmethacrylate) (PMMA) films were prepared from solution DMF/PMMA solutions. The films containing mCNT also revealed the improved dispersion.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.426-429
• /
• 2006

We investigated the electrooptical properties of a carbon nanotube (CNT)-doped nematic liquid crystal (LC) cell. Experimental results reveal that the doped CNTs influence the elastic constant of LC-CNT dispersion. Using a small amount of CNT dopant, the rise time of the LC cell is nearly invariant; the threshold voltage of the cell increases due to the increase in the elastic constant of LC-CNT dispersion. At a higher CNT concentration, the marked increase in the dielectric anisotropy of LC-CNT dispersion markedly decreases the rise time and threshold voltage of the LC cell. The fall time of this cell decreases with increasing CNT concentration due to the increase in elastic constant and the slight increase in viscosity of LC-CNT dispersion. The rise time and the fall time of the LC cell are decreased simultaneously when the LC host is doped with a moderate amount of CNT dopant.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2005.04a
• /
• pp.261-264
• /
• 2005

Since the first discovery of carbon nanotube (CNT) in 1991, a window to new technological areas has been opened. One of the emerging applications of CNTs is the reinforcement of composite materials to overcome the performance limits of conventional materials. However, because of the difficulties in distributing CNTs homogeneously in metal or ceramic matrix by means of traditional composite processes, it has been doubted whether CNTs can really reinforce metals or ceramics. In this study, CNT reinforced Cu matrix nanocomposite is fabricated by a novel fabrication process named molecular level mixing process. This process produces CNT/Cu composite powders whereby the CNTs are homogeneously implanted within Cu powders. The CNT/Cu nanocomposite, consolidated by spark plasma sintering of CNT/Cu composite powders, shows to be 3 times higher strength and 2 times higher Young’s modulus than Cu matrix. This extra-ordinary strengthening effect of carbon nanotubes in metal is higher than that of any other reinforcement ever used for metal matrix composites.

• Advances in nano research
• /
• v.2 no.1
• /
• pp.23-56
• /
• 2014

The significant growth of the Si photovoltaic industry has been so far limited due to the high cost of the Si photovoltaic system. In this regard, the most expensive factors are the intrinsic cost of silicon material and the Si solar cell fabrication processes. Conventional Si solar cells have p-n junctions inside for an efficient extraction of light-generated charge carriers. However, the p-n junction is normally formed through very expensive processes requiring very high temperature (${\sim}1000^{\circ}C$). Therefore, several systems are currently under study to form heterojunctions at low temperatures. Among them, carbon nanotube (CNT)/Si hybrid solar cells are very promising, with power conversion efficiency up to 15%. In these cells, the p-type Si layer is replaced by a semitransparent CNT film deposited at room temperature on the n-doped Si wafer, thus giving rise to an overall reduction of the total Si thickness and to the fabrication of a device with cheaper methods at low temperatures. In particular, the CNT film coating the Si wafer acts as a conductive electrode for charge carrier collection and establishes a built-in voltage for separating photocarriers. Moreover, due to the CNT film optical semitransparency, most of the incoming light is absorbed in Si; thus the efficiency of the CNT/Si device is in principle comparable to that of a conventional Si one. In this paper an overview of several factors at the basis of this device operation and of the suggested improvements to its architecture is given. In addition, still open physical/technological issues are also addressed.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.4
• /
• pp.1065-1069
• /
• 2013

A highly sensitive electrochemical detection method for bisphenol A (BPA) has been developed by using multi-walled carbon nanotube (CNT)-doped titania-Nafion composite modified glassy carbon (GC) electrode. The CNT-titania-Nafion/GC electrode exhibited excellent electrocatalytic activity towards BPA. Therefore, the CNT-titania-Nafion/GC electrode showed improved voltammetric responses for BPA compared to that obtained with bare GC electrode. In addition, cetyltrimethylammonium bromide (CTAB), a cationic surfactant, was added into the BPA sample solution in order to accumulate BPA through hydrophobic interaction between CTAB and BPA. The CNT-titania-Nafion/GC electrode gave a linear response ($r^2$ = 0.999) for BPA from $1.0{\times}10^{-8}$ M to $5.0{\times}10^{-6}$ M with a detection limit of $9.0{\times}10^{-10}$ M (S/N = 3). The modified electrode showed good selectivity against interfering species and also exhibited good reproducibility. The present electrochemical sensor based on the CNT-titania-Nafion/GC electrode was applied to the determination of BPA in food package samples.

• Polymer(Korea)
• /
• v.39 no.2
• /
• pp.293-299
• /
• 2015

Conductive microcellular foams consisted of polystrene (PS) and polydopamine-coated carbon nanotube (PDA-CNT) were prepared via high internal phase emulsion (HIPE) polymerization and their morphology and electrical conductivity were investigated. CNT as a conductive nanofiller was modified to PDA-CNT by coating with hydrophilic PDA on the surface of CNT to increase aqueous phase dispersion and emulsion stability. It was possible to prepare the HIPEs having higher PDA-CNT content and the resultant foams having improved conductivity due to its good dispersion. The foams showed the morphology of interconnected cell structure. As PDA-CNT content increased, yield stress and storage modulus increased and cell size reduced. The PDA-CNT content showing electrical percolation threshold was ca. 0.58 wt% and the conductivity at PDA-CNT content of 5 wt% was increased to $10^{-3}S/m$.