• Journal of the Korean Ceramic Society
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• v.46 no.1
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• pp.1-9
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• 2009

Activated carbon modified with nickel (Ni-AC) was employed the for preparation of Ni-activated carbon/$TiO_2$ (Ni-AC/$TiO_2$) composites. The $N_2$ adsorption data showed that the composites had a decreased surface area compared with pristine AC. This indicated blocking of the micropores on the surface of the AC, which was further supported by observation via SEM. XRD results showed that the Ni-AC/$TiO_2$ composite contained a mixed anatase and rutile phase while the untreated AC/$TiO_2$ contained only a typical single and clear anatase phase. EDX results showed the presence of C, O, and Ti with Ni peaks on the composites of Ni-AC/$TiO_2$. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photo degradation. In particular, composites treated with Ni enhanced the photo degradation behaviors of MB.

• Elastomers and Composites
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• v.49 no.1
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• pp.53-58
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• 2014

In this study, characteristics of visible-light responsive photocatalyst Weltouch, especially VOCs reduction of visible-light responsive photocatalyst coated nylon/polyester composite fiber for vehicle interior parts and materials were evaluated. Visible-light responsive photocatalyst Weltouch was observed for both anatase phase and rutile phase. It is activated by light longer than 420nm. VOCs and formaldehyde generated from visible-light responsive photocatalyst treated nylon/polyester composite fiber were reduced confirmly. Visible-light responsive photocatalyst was firmly attached to the surface of nylon/polyester composite fiber without elimination even after 25 times repeated washing. And washing durability of nylon/polyester composite fiber confirmed the excellence that reduction effects of VOCs after repeated washing has appeared as much as before washing.

• Membrane Journal
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• v.21 no.3
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• pp.229-235
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• 2011

In this study, mesoporous titania/alumina membranes were prepared by sol-gel method. Pore structure and phase composition of titania/alumina membranes could be changed by calcination temperature. The addition of alumina into titania membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of pore structures. The 5 time dip-coated membrane calcined at $450^{\circ}C$ is about $10.3{\mu}m$ in thickness with an average pore size of 5 nm. Hydrogen and nitrogen permeances through the membrane were $17.1{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$ and $4.7{\times}10^{-7}mol/m^2{\cdot}s{\cdot}Pa$, respectively. These data were explained by the Knudsen diffusion mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.215-215
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• 2012

급속한 산업의 발달은 심각한 환경오염 및 에너지 문제를 가져왔다. 이를 해결하기 위한 방안으로 수소에너지에 대한 관심이 증가하고 있으며, 수소에너지를 생산하는 방법 중 하나로 태양에너지를 원천으로 하는 광촉매(photocatalyst)에 대한 연구가 점차적으로 증가하고 있는 추세이다. 현재 광촉매로 가장 많이 사용되는 $TiO_2$의 경우, 뛰어난 광활성과 저렴한 가격, 광 안정성, 화학적 안정성을 가짐에도 불구하고, 3.2 eV라는 넓은 band gap을 가지기 때문에 385 nm 이상의 긴 파장을 갖는 가시광선은 흡수할 수 없다. 또한, 광촉매 반응과정 중 recombination으로 인한 효율의 손실이 크기 때문에 이러한 문제들을 해결하기 위해 많은 연구가 진행되어 왔다. 본 연구에서는 ICP-assisted DC magnetron sputtering 방법을 이용하여 높은 결정성을 갖는 $TiO_2$ 박막을 제조하였다. 제작된 $TiO_2$ 박막은 높은 광촉매 특성을 나타냈으며, 또한 $TiO_2$의 anatase phase와 rutile phase의 bilayer structure를 통하여 recombination을 감소시킴으로써 높은 효율을 갖는 광촉매를 제작하였다. 박막의 chemical state와 crystallinity를 확인하기 위하여 X-ray photoelectron spectroscopy와 X-ray diffractometer를 이용하여 분석을 수행하였으며, 물 분해 장치(water splitting device)를 제작하여 수소와 산소 생성시 흐르는 전류를 측정하여 광촉매 특성을 평가하였다.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.691-697
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• 1999

TiO2 powder was adsorbed on the surface of mica using the heterocoagulation method in water TiO2 powder was prepared from hydrolysis of titanium-iso propoxide in a mixed solvent of anhydrous ethanol and water. When the molar ratio of water to titanium iso-propoxide was 0.25 monodispersed spherical TiO2 particles were obtained. The prepared TiO2 powder showed anatase phase after heat treatment at 50$0^{\circ}C$ for 2 h and then transformed to rutile phase after heat treatment at 100$0^{\circ}C$ for 2h. The iso-electric points of TiO2 and Mica were pH 3.9 and pH 3.25 respectively which were measured by the Z-potential analysis in water base. The maximum Z-potential difference between two powders was observed in the range of pH 3.6~3.7 TiO2 powder was adsorbed on the surface of mica by heterocoagulation method in pH 3.6~3,7 The properties of prepared TiO2 powder was haracterized by TG-DTA, XRD and SEM The morphology and thermal properties of TiO2-adsorbed mica were examined.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.489-494
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• 2013

Nano-sized titanium oxide powders were synthesized by a polymer matrix technique using pulp and Titanium tetraisopropoxide (TTIP) as starting materials. The synthesized powders were characterized by XRD and FE-SEM. The particle size of the powders was controlled by preparation conditions, such as heat treatment temperature and time. After investigating various drying and heat treatment conditions, 50-100 nm sized homogeneous titanium oxide particles were obtained by treating at $600^{\circ}C$ for 1 h. The crystallization and rapid growth of particles was accelerated by increasing heat treatment temperature and time. Anatase phase generated below $600^{\circ}C$ transformed to the rutile phase with increasing heat treatment temperature. Moreover, above $800^{\circ}C$, heat treatment time had a very large influence on particle growth, and changing the heating condition also had a large influence on crystal growth.

• Journal of the Korean Ceramic Society
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• v.46 no.3
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• pp.234-241
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• 2009

In this study, CNT/$TiO_2$ composites derived from various titanium alkoxides and multiwalled carbon nanotubes (MWCNTs) were synthesized and characterized. Surface areas and pore volumes of the CNT/$TiO_2$ samples showed catastrophic decrease due to deposition of titanium compounds. Scanning electron microscopy (SEM) results indicated that the MWCNTs were homogenously decorated and well-dispersed onto/into the composites without apparent agglomeration of $TiO_2$ particles. In the X-ray diffraction (XRD) patterns, peaks of anatase and rutile phase were observed. The energy dispersive X-ray spectroscopy (EDX) spectra revealed the presence of major elements such as C and O with strong Ti peaks. According to the photocatalytic results, MB removal by a treatment with CNT/$TiO_2$ composites seems to have an excellent removal effect as order of CTIP, CTNB and CTPP composites due to a photolysis of the supported $TiO_2$, the radical reaction and the adsorptivity and absorptivity of the MWCNTs.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.364.1-364.1
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• 2016

We report the characteristics of individual ultra-long SnO2 nanowires(NWs) grown on sapphire(0001) substrates by vapor transport method. NWs, with typical lengths of >$400{\mu}m$, grew in the form of NW bundles under a hydrogen reducing atmosphere, without metal catalysts. The individual NWs were examined using high-resolution X-ray diffraction, transmission electron microscopy, and micro-Raman spectroscopy. The results revealed that the SnO2 NWs grew as high-quality, tetragonal-rutile-phase single crystals with mosaic distributions of $0.02^{\circ}$ and $0.026^{\circ}$ in the (101) and (110) planes, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.7
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• pp.415-418
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• 2015

In this paper, $TiO_2$ based thin-film transistors (TFTs) were fabricated using by an atomic layer deposition with high aspect ratio and excellent step coverage. $TiO_2$ semiconducting layer was deposited showing a rutile phase through the rapid thermal annealing process, and exhibited TFT characteristics with a $200{\mu}m$ channel length of low-leakage currents (none of current flow during off-state), stable threshold voltages (-10 V ~ 0 V), and a much higher on/off current ratio (<$10^5$), respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.32-32
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• 2003

최근 환경오염에 대한 문제가 심각해지면서 인체에 유해한 유기물질의 분해에 대한 관심이 높아지고 있으며 따라서 뛰어난 광촉매 특성을 보이는 타이태니아(TiO$_2$)에 대한 많은 연구가 수행되고있다. 타이태니아가 보이는 결정상 중에는 brookite, anatse, rutile이 있는데 이 중에서 anatse 상이 가장 우수한 광촉매 특성을 나타내는 것으로 알려져 있다. 그러나 anatse 상을 얻기 위해서는 $600^{\circ}C$ 이상의 온도로 열처리를 해야 한다는 문제점이 있으며 광촉매 특성을 향상시키기 위해서는 anantase 나노결정을 제조하여 표면적을 극대화시 키는 것이 요구되고 있다. 본 연구에서는 이러 한 두 가지 문제점을 해결하기 위하여 Polyethylen oxide(PEO)-TiO$_2$ 나노하이브리드를 Sol-Gel공정을 이용하여 합성하였으며 이들에 대한 hot-water treatment를 통하여 10$0^{\circ}C$ 이하의 저온에서 anatase 나노결정상의 분말을 합성하는데 성공하였다. 이는 SiO$_2$-TiO$_2$계 하이브리드에서만 hot-water treatment를 통하여 anatase로 결정화가 가능하다는 기존의 연구결과와 상반되는 결과로서 무기질 성분으로서 TiO$_2$만 존재하는 하이브리드에 대한 hoi-water treatment를 통하여 anatase결정상이 형성될 수 있었다.