• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.1
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• pp.9-14
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• 2008

A Nano particle is a small particle with at least one dimension less than 100 nm Nanoparticle is currently used in an area cf intense scientific research, due to a wide variety cf potential applications in biomedical, optical, and electronic fields. In order to know the biological effect of the nine Nano particles on fertilized egg of Crassostrea gigas experiments were performed Development rates of control (free Nano particles) C. gigas to a particular larval stage (D-shape) was 78%. Development rate of C gigas to a parcicular larval stage (D-shape) after 24 hours exposure to 0.05ppm of AGZ020, Nano silver, P-25 and SnO were 22%, 52%, 58% and 76%, respectively. However, all fertilized eggs were destructed within 8 hours afters exposure to 20ppm of respective particles. On the other hand, All fertilized eggs were not affected after 24 hours respective exposure to 0.05ppm of In, Sb, Sn, Zn, and Ag-$TiO_2$ particles. However, development rates of C. gigas after 24 hours exposure to 20ppm of In, Sb, Sn, Zn, Ag-$TiO_2$ were 57%, 60%, 50%, 65%, and 64% respectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.256-261
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• 2009

Hydrophilic and transparent $TiO_2$ thin film was fabricated by sol-gel method and the properties of contact angle, surface morphology, and transmittance were measured. In addition, surfactant Tween 80 was used for increasing the hydrophilic property of thin film. When the contents of Tween 80 in $TiO_2$ solution was 0, 10, 30, 50wt%, the contact angles of $TiO_2$ thin film were $41.4^{\circ}$, $18.2^{\circ}$, $16.0^{\circ}$, $13.2^{\circ}$, respectively. Fabricated $TiO_2$ thin film showed the photocatalytic property that decomposed methylene blue and decreased the absorbance of solution after UV irradiation. $TiO_2$ thin films fabricated with the solution of 30 wt% Tween 80 were deposited on glass (bare), antimony tin oxide (ATO), fluorine tin oxide (FTO), indium tin oxide (ITO) coated glass substrates, and the contact angle and transmittance of thin film was measured. The contact angles of thin films deposited on four substrates were $16.2\sim27.1^{\circ}$ and was decreased to the range of $13.2\sim17.6^{\circ}$ after UV irradiation, Especially, the thin films coated on ATO and FTO glass substrate showed high transmittance of 74.6% in visible range, respectively, and low transmittance of 54.2% and 40.4% in infrared range, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.771-776
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• 2017

The cover glass of mobile displays and photovoltaic cells needs a functional coating, such as an anti-reflection and self-cleaning coating. Numerous studies have been conducted on the engineering application of biomimetic functional surfaces, such as moth eye and lotus leaf Anti-reflection coantings of silica nanoparticles could enhance the light transmittance. $TiO_2$ photocatalyst coatings have been applied to self-cleaning functional films. In this study, transparent hydrophobic anti-reflective coatings consisting of thin layers of $SiO_2/TiO_2$ nanoparticles were fabricated on a slide glass substrate by the sol-gel process and dip-coating process. The dependence of the surface morphology of the functional coatings was investigated by the atomic force microscopy (AFM), contact angle measurement, and UV-visible spectroscopy. It was found that the coating of $TiO_2$ nanoparticles exhibited a high average transmittance comparable to that of the bare slide glass substrate in the visible light range. The bi-layered functional coating of 7 nm $SiO_2$/7nm $TiO_2$ nanoparticles exhibits a transparent hydrophobic surface with a contact angle of $110^{\circ}$ and an improvement of the average transmittance of 2.3% compared to the bare slide glass substrate in the visible light range.

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.1-7
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• 2012

In this article, I will introduce recent developments of environmental-friendly materials fabricated using atomic layer deposition (ALD). Advantages of ALD include fine control of the thin film thickness and formation of a homogeneous thin fim on complex-structured three-dimensional substrates. Such advantages of ALD can be exploited for fabricating environmental-friendly materials. Porous membranes such as anodic aluminum oxide (AAO) can be used as a substrate for $TiO_2$ coating with a thickness of about 10 nm, and the $TiO_2$-coated AAO can be used as filter of volatile organic compound such as toluene. The unique structural property of AAO in combination with a high adsorption capacity of amorphous $TiO_2$ can be exploited in this case. $TiO_2$ can be also deposited on nanodiamonds and Ni powder, which can be used as photocatalyst for degradation of toluene, and $CO_2$ reforming of methane catalyst, respectively. One can produce structures, in which the substrates are only partially covered by $TiO_2$ domains, and these structures turns out to be catalytically more active than bare substrates, or complete core-shell structures. We show that the ALD can be widely used not only in the semiconductor industry, but also environmental science.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.547-553
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• 2017

This study focused on the difference of photocatalytic performance by the incorporation of Pd into the $TiO_2$ framework and suggested five different catalysts composed of $TiO_2$ and x mol% $Pd-TiO_2$ (x = 0.25, 0.5, 0.75, and 1.0). A typical sol-gel method was used to synthesize catalysts, and the phenol photodegradation performance of each catalysts was evaluated. The physicochemical and optical properties of catalysts were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), ultraviolet/visible spectroscopy (UV/Vis), photoluminescence spectroscopy (PL), and photocurrent measurements. With the addition of Pd ions, the band gap of catalysts was shortened and the charge separation between photogenerated electrons and holes easily also occurred. As a result, the phenol photo-destruction performance over 0.75 mol% $Pd-TiO_2$ catalyst was 3 times higher than that of pure $TiO_2$. This is believed to be due to Pd ions acted as an electron capturing function during photocatalysis.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.1-7
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• 2017

Polydimethylsiloxane (PDMS) can be deposited on various substrates using chemical vapor deposition process, which results in the formation of PDMS thin films with thickness below 5 nm. PDMS layers can be evenly deposited on surfaces of nanoparticles composed of various chemical compositions such as $SiO_2$, $TiO_2$, ZnO, C, Ni, and NiO, and the PDMS-coated surface becomes completely hydrophobic. These hydrophobic layers are highly resistant towards degradation under acidic and basic environments and UV-exposures. Nanoparticles coated with PDMS can be used in various environmental applications: hydrophobic silica nanoparticles can selectively interact with oil from oil/water mixture, suppressing fast diffusion of spill-oil on water and allowing more facile physical separation of spill-oil from the water. Upon heat-treatments of PDMS-coated $TiO_2$ under vacuum conditions, $TiO_2$ surface becomes completely hydrophilic, accompanying formation oxygen vacancies responsible for visible-light absorption. The post-annealed $PDMS-TiO_2$ shows enhanced photocatalytic activity with respect to the bare $TiO_2$ for decomposition of organic dyes in water under visible light illumination. We show that the simple PDMS-coating process presented here can be useful in a variety of field of environmental science and technology.

• Clean Technology
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• v.18 no.3
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• pp.229-249
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• 2012

At present, global warming and depletion of fossil fuels have been one of the big issues which should be solved for sustainable development in the future. CCS (carbon capture and sequestration) technology as the post $CO_2$ reduction technology has been considered as a promising solution for global warming due to increased carbon emission. However, the environmental and ecological effects of CCS have drawn concerns. There are needs for noble post reduction technology. More recently, CCU (carbon capture and utilization) Technology, which emphasizes transforming carbon dioxide into value-added chemicals rather than storing it, has been attracted attentions in terms of preventing global warming and recycling the renewable carbon source. In this paper, various technologies developed for carbon dioxide conversion both in gas and liquid phase have been reviewed. For the thermochemical catalysis in gas phase, the development of the catalytic system which can be performed at mild condition and the separation and purification technology with low energy supply is required. For the photochemical conversion in liquid phase, efficient photosensitizers and photocatalysts should be developed, and the photoelectrochemical systems which can utilize solar and electric energy simultaneously are also in development for more efficient carbon dioxide conversion. The energy needed in CCU must be renewable or unutilized one. CCU will be a key connection technology between renewable energy and bio industry development.

• Solar Energy
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• v.12 no.3
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• pp.10-20
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• 1992

In this experiment, photochemical reaction has been applied to destroy TCE in water phase. The main target of this work is to investigate the technical feasibility of large scale of solar detoxification reactor for water treatment. The results have revealed that solar detoxification utilizing photon energy from the sun is the most attractive process to decompose organic toxins in water phase at room temperature. The detailed results from this work are as follows; (1) The highest conversion ratio of TCE was obtained by using $TiO_2$, annatase as a photocatalyst among $TiO_2$ anatase, $TiO_2$ rutile and $V_2O_5$ under the same experimental condition. The anatase crystal structure was confirmed with XRD analysis, and its surface area was 7.748 $m^2/g$ from the BET-$N_2$ measurement (2) 0.1 wt% of $TiO_2$ anatase has been adopted as optimal quantity for batch slurry reactor at this experimental conditions. (3) The effect of hydrogen peroxide on the conversion of TCE was investigated. Its optimal quantity was 0.06 vol. % under this experimental conditions. (4) The effect of oxygen on the conversion of TCE also was studied by controlling the head space in photoreactor. Results indicated that sufficient amount of oxygen should be supplied to accomplish the highest conversion rate of TCE in water phase.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.158-158
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• 2016

최근 화석연료의 고갈과 환경 보전 및 에너지 절약에 대한 관심이 높아짐에 따라 화석연료의 소비를 최소화하고 실내조건을 쾌적하게 유지하려는 연구가 진행되고 있다. 국내의 경우 전체 에너지 소비의 30%이상을 차지하고 있는 건물부문에서의 에너지 소비를 줄이기 위한 활발한 연구가 진행되고 있으며 이에 따른 에너지절약 소재개발이 활발하게 진행되고 있다. 1975년 이후 여러 차례에 걸친 단열강화 조치를 통해 건물에서의 에너지 소모를 줄이고 있었으나 건물의 외벽에 대한 사항으로 한정되어있었고, 또한 건물의 창 면적이 증가함에 따라 창을 통한 열손실량과 열획득량이 더욱 증가하게 되었다. 이러한 문제를 해결하기 위해 열반사유리에 대한 많은 연구가 진행되고 있다. 열반사유리는 근적외선(열선)영역의 빛을 반사시켜 실내의 열손실량 및 외부에서의 열획득량을 감소시켜 에너지의 소비를 줄일 수 있는 유리을 말한다. 이러한 열반사유리은 fresnel 방정식을 통해 빛의 파장대에 따른 반사율 및 투과도를 예측할 수 있는데, 다층박막구조인 Oxide-Metal-Oxide(OMO)구조는 Oxide의 높은 굴절률과 Metal의 낮은 굴절률을 통해 가시광영역대의 높은 투과도와 근적외선 영역의 높은 반사율을 얻을 수 있다. 또한 Metal층을 삽입함으로서 flexible한 코팅이 가능하고, 높은 carrier density와 mobility로 표면 플라즈몬 공명을 통해 특정 파장대의 반사율을 높일 수 있으므로 많은 연구가 진행되고 있다. $TiO_2$는 고굴절률 및 낮은 광흡수성의 특성을 가지는 산화물반도체로 기존의 $In_2O_3$계 산화물에 비해 값이 싸고 높은 안정성과 광촉매특성을 보이므로 외부에 노출된 환경에 적합한 재료이다. Ag는 저굴절률과 낮은 광흡수성을 가지는 재료로 금속층에 적합하다. 본 연구에서는 fresnel 방정식을 통해 반사도 및 투과도를 예측하고 마그네트론 스퍼터링법으로 다층박막을 열선인 적외선 영역에서의 반사율 및 반사 효율을 평가하였다. Index-matching 시뮬레이션을 통해 $TiO_2/Ag/TiO_2$ 다층박막의 투과도와 반사도를 이론적으로 검토하였다. 시뮬레이션 프로그램은 Macleod프로그램을 이용하였고 재료 각각의 굴절률은 Ellipsometry를 이용하여 측정하였다. 두께 40 nm 와 8 ~ 16 nm를 가지는 $TiO_2$층과 Ag층을 각각 RF/DC 마그네트론 스퍼터링법을 이용하여 Glass기판 위에 증착하였다. 직경 3 in 의 $TiO_2$, Ag 소결체 타깃을 이용하였고 스퍼터링 파워는 각각 200 W, 50 W로 설정하였고, 스퍼터링 가스는 Ar가스의 유량을 20 sccm으로 설정하였다. 작업압력은 모두 1 Pa로 설정하였고 타깃 표면의 불순물 및 이물질 제거를 위해 Pre-sputtering을 10분 진행하였다. 박막의 두께는 reflectometer와 Alphastep을 이용하여 측정하였고 Hall effect measurement를 이용하여 비저항, carrier density, mobility등 전기적 특성을 측정하였다. 또한 UV-VIS spectrometer와 USPM-RU-W NIR Micro-Spectrophotometer를 통해 광학적 특성을 측정하였고 계산 값과 비교분석하였다. 또한 열반사 특성을 평가하기 위해 직접 set-up한 장비를 이용하였다. 단열 박스에 샘플을 장착해 적외선 램프를 조사하였을 때의 열 반사효율을 평가하였고, IR Camera를 이용하여 단열 박스 내부의 온도 변화를 관찰하였다.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.426-431
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• 2013

Nanosized $TiO_2$ particles were prepared from titanium (IV) sulfate solution using base solutions at low reaction temperature ($95^{\circ}C$) and atmospheric pressure by hydrothermal precipitation method without calcination. The effects of preparation conditions, such as kind of base solutions (NaOH, $NH_4OH$, Monoethanolamine, Diethanolamine, Triethanolamine) and surfactants (CTAB, Span 20, SDBS), concentration of surfactants, temperature and pH, on the physical properties of $TiO_2$ particles have been investigated by XRD, SEM and Zeta-potential meter. Absorption area was also investigated by DRS in order to confirm the photocatalytic activity of the nanosized $TiO_2$ particles. It was turned out that, among base solutions, NaOH provides the smallest $TiO_2$ particles with excellent crystallinity. And cationic surfactant (CTAB) prepared smaller $TiO_2$ particles than any other surfactants. When CTAB is added in the concentration ratio of $Ti(SO_4)_2$:CTAB=10:1, $TiO_2$ particles with particle diameter of 5.8 nm were prepared. This is approximately 1/10 of that prepared without CTAB.