• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.312-312
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• 2006

Block copolymers with well-defined nanoscopic structures have recently gained much attention for their potential uses as functional nanostructures. Here, we show that nanoporous templates made from polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) satisfy a novel design concept. At first, arrays of nanoscopic cylindrical microdomains oriented normal to the surface can easily be prepared. Then, we fabricated ultra high density arrays of conducting polymer as poly(pyrrole) (Ppy) and poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires with diameters of $25{\sim}40\;nm$ on the ITO glass by electropolymerization of the monomers inside nanoholes. These high density arrays of conducting polymer nanowires could be used as P-type materials for photovoltaic devices.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.161-163
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• 2002

Siver nanowires have been obtained by electrodepositon in the porous anodic alumina that plays a role as a template in the constant current mode using DC power supply. The diameter and the length of the silver nanowires are about 55 nm and 13 ${\mu}m$ corresponding to them of the template respectively. The aspect ratio of the silver nanowires is more or less 200. The rate of the filling of the alumina pores is approximately 10%.

• Journal of the Korean Ceramic Society
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• v.45 no.4
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• pp.191-195
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• 2008

Highly ordered silver nanowire with a diameter of 10 nm was arrayed by electroless deposition in a porous anodic aluminum oxide(AAO) membrane. The AAO membrane was fabricated electrochemically in an oxalic acid solution via a two-step anodization process, while growth of the silver nanowire was initiated by using electroless deposition at the long-range-ordered nanochannels of the AAO membrane followed by thermal reduction of a silver nitrate aqueous solution by increasing the temperature up to $350^{\circ}C$ for an hour. An additional electro-chemical procedure was applied after the two-step anodization to control the pore size and channel density of AAO, which enabled us to fabricate highly-ordered silver nanowire on a large scale. Electroless deposition of silver nitrate aqueous solution into the AAO membrane and thermal reduction of silver nanowires was performed by increasing the temperature up to $350^{\circ}C$ for 1 h. The morphologies of silver nanowires arrayed in the AAO membrane were investigated using SEM. The chemical composition and crystalline structure were confirmed by XRD and EDX. The electroless-deposited silver nanowires in AAO revealed a well-crystallized self-ordered array with a width of 10 nm.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1519-1523
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• 2002

A procedure for preparing semiconductor/metal nanowire arrays is described, based on a template method which entails electrochemical deposition into nanometer-wide parallel pores of anodic aluminum oxide films on aluminum. Aligned CdS/Co heterostructured nanowires have been prepared by ac electrodeposition in the anodic aluminum oxide templates. By varying the preparation conditions, a variety of CdS/Co nanowire arrays were fabricated, whose dimensional properties could be adjusted.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.7.1-7.1
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• 2011

Nanoporous templates have been widely used for the development of new functional nanostructured materials suitable for electronics, optics, magnetism, and energy storage materials. We have prepared nanoporous templates by using thin films of mixtures of polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA) and PMMA homopolymers. These templates have cylindrical nanoholes spanning the entire thickness of the film. Some applications of nanoporous templates are introduced: a) anti-reflective coating, b) the preparation of conducting polymer nanowires of poly (pyrrole), poly (3,4-ethylenedioxy-thiopene) onto a glass coated with indium-tin-oxide, and c) the separation membranes for biomaterials. We found that when the pore fraction of nanoholes in the film was ~0.68, almost zero reflectance at a specific wavelength, which can be changed with film thickness, was achieved at visible wavelengths Furthermore, ultra high density array of conducting nanowires was successfully prepared onto various substrates including flexible polymer. Due to highly alignment of polymer chain along the nanowire direction, the conductivity was much increased. Furthermore, these nanoporous films were found to be very effective for the separation of human Rhinovirus type 14 (HRV 14), major pathogen of a common cold in humans, from the buffer solution. We also found that when the pore size was effectively controlled down to 6 nm, a single file diffusion was observed.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.653-658
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• 2016

In this work, we developed a synthetic method for preparing one-dimensional $MnO_2$ nanowires through a hydrothermal method using a mixture of $KMnO_4$ and $MnSO_4$ precursors. As-prepared $MnO_2$ nanowires had a high surface area and porous structure, which are beneficial to the fast electron and ion transfer during electrochemical reaction. The microstructure and chemical structure of $MnO_2$ nanowires were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller measurements. The electrochemical properties of $MnO_2$ nanowire electrodes were also investigated using cyclic voltammetry and galvanostatic charge-discharge with a three-electrode system. $MnO_2$ nanowire electrodes showed a high specific capacitance of 129 F/g, a high rate capability of 61% retention, and an excellent cycle life of 100% during 1000 cycles.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1493-1494
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• 2011

CdS nanostructure materials have been fabricated in porous anodic aluminum oxide (AAO) template by using chemical bath deposition (CBD). These nanostructure materials had uniform diameters of about 15e200 nm, which correspond to the pore sizes of the templates used, and the length was up to 40 mm. X-ray diffraction (XRD) investigation demonstrates that CdS nanostructure materials were hexagonal polycrystalline in nature. As the pore diameter of AAO templates was enlarged, the preferential orientation of c-axis was improved. From PL analysis, the sulfur-deficient defects at the surfaces of CdS nanostructure materials were increasedwhen the samplewas synthesized in the template with larger pore diameter.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.238-246
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• 2015

$H_2S$ is a flammable toxic gas that can be produced in plants, mines, and industries and is especially fatal to human body. In this study, CuO nanowire structure with high porosity was fabricated by deposition of copper on highly porous singlewall carbon nanotube (SWCNT) template followed by oxidation. The SWCNT template was formed on alumina substrates by the arc-discharge method. The oxidation temperatures for Cu nanowires were varied from 400 to $800^{\circ}C$. The morphology and sensing properties of the CuO nanowire sensor were characterized by FESEM, Raman spectroscopy, XPS, XRD, and currentvoltage examination. The $H_2S$ gas sensing properties were carried out at different operating temperatures using dry air as the carrier gas. The CuO nanowire structure oxidized at $800^{\circ}C$ showed the highest response at the lowest operating temperature of $150^{\circ}C$. The optimum operating temperature was shifted to higher temperature to $300^{\circ}C$ as the oxidation temperature was lowered. The results were discussed based on the mechanisms of the reaction with ionosorbed oxygen and the CuS formation reaction on the surface.

• Korean Journal of Materials Research
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• v.20 no.4
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• pp.199-203
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• 2010

Hybridization of semiconductor materials with carbon nanotubes (CNTs) is a recent field of interest in which new nanodevice fabrication and applications are expected. In this work, nanowire type GaAs structures are synthesized on porous single-wall carbon nanotubes (SWCNTs) as templates using the molecular beam epitaxy (MBE) technique. The field emission properties of the as-synthesized products were investigated to suggest their potential applications as cold electron sources, as well. The SWCNT template was synthesized by the arc-discharge method. SWCNT samples were heat-treated at $400^{\circ}C$ under an $N_2/O_2$ atmosphere to remove amorphous carbon. After heat treatment, GaAs was grown on the SWCNT template. The growth conditions of the GaAs in the MBE system were set by changing the growth temperatures from $400^{\circ}C$ to $600^{\circ}C$. The morphology of the GaAs synthesized on the SWCNTs strongly depends on the substrate temperature. Namely, nano-crystalline beads of GaAs are formed on the CNTs under $500^{\circ}C$, while nanowire structures begin to form on the beads above $600^{\circ}C$. The crystal qualities of GaAs and SWCNT were examined by X-ray diffraction and Raman spectra. The field emission properties of the synthesized GaAs nanowires were also investigated and a low turn-on field of $2.0\;V/{\mu}m$ was achieved. But, the turn-on field was increased in the second and third measurements. It is thought that arsenic atoms were evaporated during the measurement of the field emission.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.623-627
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• 2010

Semiconducting metal oxides have been frequently used as gas sensing materials. While zinc oxide is a popular material for such applications, structures such as nanowires, nanorods and nanotubes, due to their large surface area, are natural candidates for use as gas sensors of higher sensitivity. The compound ZnO has been studied, due to its chemical and thermal stability, for use as an n-type semiconducting gas sensor. ZnO has a large exciton binding energy and a large bandgap energy at room temperature. Also, ZnO is sensitive to toxic and combustible gases. The NO gas properties of zinc oxide-single wall carbon nanotube (ZnO-SWCNT) composites were investigated. Fabrication includes the deposition of porous SWCNTs on thermally oxidized $SiO_2$ substrates followed by sputter deposition of Zn and thermal oxidation at $400^{\circ}C$ in oxygen. The Zn films were controlled to 50 nm thicknesses. The effects of microstructure and gas sensing properties were studied for process optimization through comparison of ZnO-SWCNT composites with ZnO film. The basic sensor response behavior to 10 ppm NO gas were checked at different operation temperatures in the range of $150-300^{\circ}C$. The highest sensor responses were observed at $300^{\circ}C$ in ZnO film and $250^{\circ}C$ in ZnO-SWCNT composites. The ZnO-SWCNT composite sensor showed a sensor response (~1300%) five times higher than that of pure ZnO thin film sensors at an operation temperature of $250^{\circ}C$.