• 한국재료학회지
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• 제24권8호
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• pp.423-428
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• 2014

We synthesized Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell nanowires(NWs) by means of a co-electrospinning method and demonstrated their magnetic properties. To investigate the structural, morphological, chemical, and magnetic properties of the samples, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were used, as was a vibrating sample magnetometer. The morphology of the nanostructures obtained after calcination at $500^{\circ}C$ exhibited core/shell NWs consisting of $TiO_2$ in the core region and ${\alpha}-Fe_2O_3$ in the shell region. In addition, the XPS results confirmed the formation of Fe-doped $TiO_2$ by the doping effect of $Fe^{3+}$ ions into the $TiO_2$ lattice, which can affect the ferromagnetic properties in the core region. For comparison, pure ${\alpha}-Fe_2O_3$ NWs were also fabricated using an electrospinning method. With regard to the magnetic properties, the Fe-doped $TiO_2/{\alpha}-Fe_2O_3$ core-shell NWs exhibited improved saturation magnetization(Ms) of approximately ~2.96 emu/g, which is approximately 6.1 times larger than that of pure ${\alpha}-Fe_2O_3$ NWs. The performance enhancement can be explained by three main mechanisms: the doping effect of Fe ions into the $TiO_2$ lattice, the size effect of the $Fe_2O3_$ nanoparticles, and the structural effect of the core-shell nanostructures.

• Toxicological Research
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• 제25권4호
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• pp.195-201
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• 2009

Recent publications showed that metal nanoparticles which are made from $TiO_2,\;CeO_2,\;Al_2O_3,\;CuCl_2,\;AgNO_3$ and $ZnO_2$ induced oxidative stress and pro-inflammatory effects in cultured cells and the responses seemed to be common toxic pathway of metal nanoparticles to the ultimate toxicity in animals as well as cellular level. In this study, we compared the gene expression induced by two different types of metal oxide nanoparticles, titanium dioxide nanoparticles (TNP) and cerium dioxide nanoparticles (CNP) using microarray analysis. About 50 genes including interleukin 6, interleukin 1, platelet-derived growth factor $\beta$, and leukemia inhibitory factor were induced in cultured BEAS2B cells treated with TNP 40 ppm. When we compared the induction levels of genes in TNP-treated cells to those in CNP-treated cells, the induction levels were very correlated in various gene categories (r=0.645). This may suggest a possible common toxic mechanism of metal oxide nanoparticles.

• 대한화학회지
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• 제56권1호
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• pp.92-101
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• 2012

The degradation of one of the commercially important hydrogel based on acrylic acid and acryl amide, (acrylic acid-co-acryl amide) hydrogels, by means of ultrasound irradiation and its combination with heterogeneous ($TiO_2$) was investigated. 24 kHz of ultrasound irradiation was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. The extent of sonolytic degradation increased with increasing ultrasound power (in the range 30-80 W). $TiO_2$ sonophotocatalysis led to complete (acrylic acid-co-acryl amide) hydrogels degradation with increasing catalyst loading, while, the presence of $TiO_2$ in the dark generally had little effect on degradation. Therefore, emphasis was totally on the sonolytic and sonophotocatalytic degradation of hydrogels and a synergy effect was calculated for combined degradation procedures (Ultrasound and Ultraviolet) in the presence of $TiO_2$ nanoparticles. $TiO_2$ sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasound-induced increase of the active surface area of the catalyst. A kinetics model based on viscosity data was used for estimation of degradation rate constants at different conditions and a negative order for the dependence of the reaction rate on total molar concentration of (acrylic acid-co-acryl amide) hydrogels solution within the degradation process was suggested.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.771-776
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• 2017

모바일 디스플레이 및 태양전지의 커버글라스에는 반사방지 코팅 및 셀프클리닝과 같은 기능성 코팅이 필요하다. 최근 들어 나방 눈 또는 연꽃 잎과 같은 자연의 기능성 표면을 모사하여 공학적으로 응용하고자하는 많은 연구가 수행되었다. 특히 실리카 나노입자를 이용한 반사방지 기능성 코팅은 빛의 투과를 증가시키며, $TiO_2$ 광촉매 코팅은 셀프클리닝 기능성 필름에 적용되어왔다. 본 연구에서는 $SiO_2/TiO_2$ 나노입자의 박막 코팅에 의한 투명 발수 반사방지 코팅을 sol-gel 공정과 dip-coating 공정으로 글라스 기판 위에 제조하였다. 기능성 코팅의 표면형상 의존성을 원자힘현미경, 접촉각 측정 및 UV-visible 분광광도계 분석으로 조사하였다. 그 결과 $TiO_2$ 나노입자의 코팅은 가시광선 영역에서 투과율을 저하시키지 않고 기판인 슬라이드 글라스와 비슷한 수준의 높은 평균 광 투과율을 나타내었다. 또한 7nm $SiO_2$/7nm $TiO_2$ 나노입자의 이중층 기능성 코팅은 접촉각 $110^{\circ}$의 투명 발수 표면 특성을 나타내었으며, 가시광선 영역에서 기판인 슬라이드 글라스 보다 2.3% 높은 평균 투과율의 향상을 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.415-418
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• 2014

Phenyltrimethoxysilane (PTMS) was anchored onto the sensitized $TiO_2$ nanoparticles. This insulating molecular layer effectively inhibited the charge recombination at the interface of $TiO_2$/electrolyte in the dye-sensitized solar cells (DSCs) without sacrificing the dye-loading capacity of the nanocrystalline $TiO_2$. DSCs using PTMS-modified $TiO_2$ exhibited a short-circuit current ($J_{SC}$) of $15.9mA/cm^2$, an open-circuit voltage ($V_{OC}$) of 789 mV, and a fill factor (FF) of 68.2%, yielding an overall conversion efficiency (${\eta}$) of 8.55% under $100mW/cm^2$ illumination. The resulting cell efficiency was improved by ~10% as compared with the reference cell.

• 대한환경공학회지
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• 제31권11호
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• pp.1019-1024
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• 2009

가시광 활성을 갖는 anatase 결정구조의 $TiO_2-_xN_x$ 나노입자를 암모니아 수용액에서 $TiCl_4$ 가수분해에 의해 제조하였다. 제조한 시료의 특성은 XRD, TEM, $N_2$-sorption 및 DRS로 분석하였다. 질소를 $TiO_2$에 도핑함으로써 광흡수 영역이 순수한 TiO2에 해당하는 390 nm에서 가시광 영역인 530 nm까지 이동하였다. DRS 분석결과로부터 $TiO_2-_xN_x$의 밴드갭이 감소하는 것을 유추할 수 있었다. 광촉매 활성은 가시광 조사하에서 congo red 분해로부터 평가하였다. 질소의 도핑 농도가 적절한 광촉매가 광촉매 활성이 가장 높게 나타났다. 이러한 결과로부터 질소 도핑이 광촉매 활성의 향상에 중요한 역할을 함을 확인할 수 있었다.

• 대한화학회지
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• 제63권4호
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• pp.307-311
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• 2019

• Current Photovoltaic Research
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• 제4권2호
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• pp.42-47
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• 2016

Increasing the efficiency of dye-sensitized solar cells (DSSCs) by the fabrication of new photoelectrodes (PEs) is an important challenge. This study examined the photovoltaic parameters of DSSCs composed of a $TiO_2$ PE with $WO_3$ nanoparticles (NPs). A number of PEs with the same thickness but different concentrations of $WO_3$ NPs in the $TiO_2PE$ were prepared. The morphology and structural properties of the prepared PEs were examined by field-emission scanning electron microscopy and X-ray diffraction, respectively. The effects of the $WO_3$ NPs mixing concentration on the efficiency of DSSCs were investigated under simulated solar light irradiation.

• 한국응용과학기술학회지
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• 제30권1호
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• pp.49-56
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• 2013

Excellent electron transport properties with enhanced light scattering ability for light harvesting have made well-ordered one dimensional $TiO_2$ nanotube(TNT) arrays an alternative candidate over $TiO_2$ nanoparticles in the area of solar energy conversion applications. The principal drawback of TNT arrays being activated only by UV light has been addressed by coupling the TNT with secondary materials which are visible light-triggered. As well as extending the absorption region of sunlight, the introduction of these foreign components is also found to influence the charge separation and electron lifetime of TNT. In this study, a novel method to fabricate the TNT-based composite photoelectrodes employing visible responsive $CuInS_2$ (CIS) nanoparticles is presented. The developed method is a square wave pulse-assisted electrochemical deposition approach to wrap the inner and outer walls of a TNT array with CIS nanoparticles. Instead of coating as a dense compact layer of CIS by a conventional non-pulsed-electrochemical deposition method, the nanoparticles pack relatively loosely to form a rough surface which increases the surface area of the composite and results in a higher degree of light scattering within the tubular channels and hence a greater chance of absorption. The excellence coverage of CIS on the tubular $TiO_2$ allows the construction of an effective heterojunction that exhibits enhanced photoelectrochemical performance.

• 공업화학
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• 제28권1호
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• pp.1-7
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• 2017

폴리디메틸실록산(PDMS)은 화학적 증기 증착 방법을 통해 다양한 물질에 5 nm 두께 이하의 박막 형태로 증착될 수 있다. $SiO_2$, $TiO_2$, ZnO, C, Ni 및 NiO와 같은 다양한 종류의 나노입자 표면에도 PDMS 박막은 증기 증착을 통해 고르게 형성될 수 있으며, PDMS가 증착된 표면은 완벽한 소수성을 갖게 된다. 이 소수성 박막은 안정성이 높아 산, 염기 및 자외선 노출 시에도 잘 분해되지 않으며, 또한 PDMS로 코팅된 나노입자는 다양한 환경 분야에 응용될 수 있다. PDMS 코팅된 소수성 $SiO_2$ 입자는 기름/물 혼합액에서 기름과 선택적으로 반응하고, 기름 유출 사고 시 유류 확산을 억제할 수 있으며, 유출된 기름을 물에서 물리적으로 쉽게 분리할 수 있게 해준다. PDMS 코팅된 $TiO_2$를 진공 상태에서 열처리 할 경우 $TiO_2$ 표면은 완전하게 친수성으로 개질되며, 이때 $TiO_2$가 가시광선을 흡수하여 반응할 수 있게 하는 산소 빈자리 또한 발생하게 된다. PDMS 코팅 후 열처리한 $TiO_2$는 아무 처리하지 않은 $TiO_2$에 비해 가시광 하에서 수중의 유기 염료를 분해하는데 더 뛰어난 광촉매 활성을 보인다. 우리는 해당 연구에서 제시하는 간단한 PDMS 박막 코팅 방법이 다양한 환경 과학 및 공학 분야에서 응용될 수 있음을 소개하고자 한다.