• 한국포장학회지
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• 제23권2호
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• pp.67-74
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• 2017

In this work, the effects of nano $TiO_2$ on functionality and stability of low density polyethylene (LDPE) composite films were investigated for food packaging application. LDPE-nano $TiO_2$ composite films were prepared with various $TiO_2$ contents (0, 0.5, 1.0, 3.0 and 5.0wt%) by melt-extrusion and their basic properties such as crystallinity, chemical bonds and surface morphology were examined by XRD, FTIR and SEM. Ultraviolet (UV) light barrier property of as-prepared LDPE-nano $TiO_2$ composite films was also studied and the presence of nano $TiO_2$ resulted in significant improvement of UV light barrier compared to the pure LDPE film. To evaluate influence of nano $TiO_2$ on LDPE properties required as packaging material, thermal, mechanical, gas barrier and optical properties of LDPE-nano $TiO_2$ composite films were characterized with various analytical techniques including TGA, UTM, OTR, WVTR and UV-vis spectroscopy. As a result, except optical property of LDPE, no significant effects were found in other properties. Opacity of pure LDPE was greatly increased with increasing concentration of nano $TiO_2$.

• Current Photovoltaic Research
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• 제1권2호
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• pp.90-96
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• 2013

We report here flexible dye-sensitized solar cells (DSSC) based on Ti-mesh electrodes that show good mechanical flexibility and electrical conductivity. $TiO_2$ nanotube arrays prepared by electrochemical anodizing Ti-mesh substrate were used as photoanode. A Pt-coated Ti-mesh substrate was used as counter electrode. The photoanodes were modified by coating a $TiO_2$ porous layer onto the $TiO_2$ nanotubes in order to increase the specific surface area. To increase the long term stability of the DSSCs, a gel type electrolyte was used instead of a conventional liquid type electrolyte. The DSSC based on $33.2{\mu}m$ long porous $TiO_2$ nanotubes exhibited a better energy conversion efficiency of ~2.33%, which was higher than that of the DSSCs based on non-porous $TiO_2$ nanotubes.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.137-140
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• 2001

Oragnic/inorganic hybrid materials prepared by sol-gel method have rapidly become a fasci nating research field in materials science. In this study, Polyimide/$\textrm{TiO}_2$ composites were synthesized from nano-sized anatase $\textrm{TiO}_2$ and two types of Polyimide (BTDA-PPD, PMDA-ODA) by Sol-gel method. Nano-sized $\textrm{TiO}_2$ particles were prepared from $\textrm{TiOEt}_4$ solution. The composites were charcaterized by using XRD, TGA, IR, TEM, and Atomic Force Microscope(AFM). $\textrm{TiO}_2$ nano particles were dispersed well in polyimide matrix and the thermal stability of polyimide was improved with $\textrm{TiO}_2$ nano-sized particles.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.52-56
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• 2006

Some of factors affecting photo-conversion efficiency of dye sensitized solar cells (DSCs) are discussed in terms of $TiO_2$ electrodes. The first topic is on the surface modification of $TiO_2$ nano-particles, which is associated with electron traps on the surface of $TiO_2$ nano-particles. The surface is modified with dye molecules under pressurized $CO_2$ atmosphere to increase the surface coverage of $TiO_2$ nano-particles with dye molecules. This increases Jsc because of an increase in the amount of dye molecules and a decrease in the amount of trapping sites on $TiO_2$ nano-particles. In addition, the decrease in the amount of trap sites increases Voc because decreases in Voc are brought about by the recombination of $I_2$ molecules with electrons trapped on the $TiO_2$ surfaces. Selective staining for tandem cells is proposed. The second topic is on the contact between a $SnO_2$/F transparent conductive layer (TCL) and nano-particles. Polishing the TCL surfaces with silica nano-particles increases the contact, resulting in Jsc increases. The third topic is the fabrication of ion-paths in $TiO_2$ layers. Electro-spray coating of $TiO_2$ nano-particles onto TCL is shown to be effective for fabricating ion-paths in $TiO_2$ layers, which increases Jsc.

• 폴리머
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• 제38권2호
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• pp.150-155
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• 2014

Polycaprolactone(PCL)은 생분해성 고분자로 인장강도, 신장률, 충격강도 등의 기계적 물성이 우수하다. $TiO_2$ (titanium dioxide) nanoparticle은 친수성으로 밀도가 높고 생체적합성이 우수하다. 본 연구에서는 PCL과 $TiO_2$(titanium dioxide) nanoparticle을 이용하여 salt-leaching방법으로 3차원 다공성 지지체를 제작하였다. 제작한 지지체를 FESEM, FTIR, TGA, 압축강도 측정 등을 통해 물성을 분석하였다. $TiO_2$ nanoparticle에 의해 물흡수도와 팽윤도는 감소하였으나 압축강도는 증가하였다. CCK-8 assay를 통해 세포의 증식률을 확인한 결과, $TiO_2$ nanoparticle에 의한 세포 독성은 없는 것으로 확인되었다. 이러한 연구결과는 PCL/$TiO_2$ nanoparticle 지지체의 생체재료로 사용가능성을 제시하였다.

• Environmental Engineering Research
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• 제16권2호
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• pp.81-90
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• 2011

Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

• Journal of Welding and Joining
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• 제21권4호
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• pp.39-45
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• 2003

Nano-TiO$_2$ photocatalytic coatings were deposited on the stainless steel 304(50$\times$70$\times$3mm) by the APS(Atmospheric Plasma Spraying). Photocatlytic reaction was tested in MB(methylene blue) aqueous solution. For applying nano-TiO$_2$ powders by thermal spray, the starting nano-TiO$_2$ powder with 100% anatase crystalline was agglomerated by spray drying. Plasma second gas(H$_2$) flow rate and spraying distance were used as principal process parameters which are known to control heat enthalpy(heat input). The relationship between process parameters and the characteristics of microstructure such as the anatase phase fraction and grain size of the TiO$_2$ coatings were investigated. The photo-decomposition efficiency of TiO$_2$ coatings was evaluated by the kinetics of MB aqueous solution decomposition. It was found that the TiO$_2$ coating with a lower heat input condition had a higher anatase fraction, smaller anatase grain size and a better photo-decomposition efficiency.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2133-2139
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• 2012

A new system using $TiO_2$ (nano-sized, band-gap 3.14 eV)-impregnated spherical ZnS (micro-sized, band-gap 2.73 eV) nano/micro-composites (Ti 0.001, 0.005, 0.01, and 0.05 mol %/ZnS) was developed to enhance the production of hydrogen from methanol/water splitting. The ZnS particles in a spherical morphology with a diameter of about 2-4 mm which can absorb around 455 nm were prepared by hydrothermal method. This material was used as a photocatalyst with loading by nano-sized $TiO_2$ (20-30 nm) for hydrogen production. The evolution of $H_2$ from methanol/water (1:1) photo splitting over the $TiO_2$/ZnS composite in the liquid system was enhanced, compared with that over pure $TiO_2$ and ZnS. In particular, 1.2 mmol of $H_2$ gas was produced after 12 h when 0.005 mol % $TiO_2$/ZnS nano/micro-composite was used. On the basis of cyclic voltammeter (CV) and UV-visible spectrums results, the high photoactivity was attributed to the larger band gap and the lower LUMO in the $TiO_2$/ZnS composite, due to the decreased recombination between the excited electrons and holes.

• 센서학회지
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• 제18권3호
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• pp.239-244
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• 2009

We fabricated nano-templates by low temperature BCP(block copolymer) process at 180 $^{\circ}C$, then we deposited 10 nm-thick $TiO_2$ layers with ALD(atomic layer deposition) at low temperature of 150 $^{\circ}C$. Through FE-SEM analysis, we confirmed the successful formation of the groove-type(width of crest : 30 nm, width of trough : 18 nm) and the cylinder-type(diameter : 10 nm, distance between hole : 25 nm) templates. Moreover, after $TiO_2$-ALD processing, we confirmed the deposition of the uniform nano layers of $TiO_2$ on the nano-templates. Through AFM analysis, the pitches of the crest-through(in groove-type) and hole-hole(in cylinder-type) were the same before and after $TiO_2$-ALD processing. In addition, we indirectly determined the existence of the uniform $TiO_2$ layers on nano-templates as the surface roughness decreased drastically. We successfully fabricated nano-template at low temperature and confirmed that the three-dimensional nano-structure for sensor application could be achieved by $TiO_2$-ALD processing at extremely low temperature of 150 $^{\circ}C$.

• 한국표면공학회지
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• 제52권6호
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• pp.298-305
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• 2019

We investigated a correlation between morphology and photoelectrochemical properties of TiO₂ nanotubes fabricated by well-controlled anodization processes. Anodization in an ethylene-glycol-based electrolyte solution accelerated the rapid grow rate of TiO₂ nanotubes, but also cause problems such as delamination at the interface between TiO₂ nanotubes and a Ti substrate, and debris on the top of the nanotube. The applied voltages for the anodization of TiO₂ were adjusted to avoid the interface delamination. The heat treatment and the anodizing time were also controlled to enhance the crystallinity of the as-prepared TiO₂ nanotubes and to increase the surface area with the varied length of the anodized TiO₂ nanotubes. Additionally, a 2-step anodization process was utilized to remove the debris on the tube top. The photoelectrochemical properties of TiO₂ nanotubes prepared with the carefully tailored conditions were investigated. By removing the debris on TiO₂ nanotubes, applied bias photon-to-current efficiency (ABPE) of TiO₂ nanotubes increased up to 0.33%.