• 한국재료학회지
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• 제32권11호
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• pp.496-507
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• 2022

For the selective catalytic reduction of NOx with ammonia (NH₃-SCR), a V₂O₅WO₃/TiO₂ (VW/nTi) catalyst was prepared using V₂O₅ and WO₃ on a nanodispersed TiO₂ (nTi) support by simple impregnation process. The nTi support was dispersed for 0~3 hrs under controlled bead-milling in ethanol. The average particle size (D₅₀) of nTi was reduced from 582 nm to 93 nm depending on the milling time. The NOx activity of these catalysts with maximum temperature shift was influenced by the dispersion of the TiO₂. For the V_0.5W₂/nTi-0h catalyst, prepared with 582 nm nTi-0h before milling, the decomposition temperature with over 94 % NOx conversion had a narrow temperature window, within the range of 365-391 ℃. Similarly, the V_0.5W₂/nTi-2h catalyst, prepared with 107 nm nTi-2h bead-milled for 2hrs, showed a broad temperature window in the range of 358~450 ℃. However, the V_0.5W₂/Ti catalyst (D₅₀ = 2.4 ㎛, aqueous, without milling) was observed at 325-385 ℃. Our results could pave the way for the production of effective NOx decomposition catalysts with a higher temperature range. This approach is also better at facilitating the dispersion on the support material. NH₃-TPD, H₂-TPR, FT-IR, and XPS were used to investigate the role of nTi in the DeNOx catalyst.

• 한국세라믹학회지
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• 제39권4호
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• pp.336-340
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• 2002

Pure and nano-sized $TiO_2$ and $CaTiO_3$ powders were fabricated by a polymeric steric entrapment route and planetary milling process. An ethylene glycol was used as a polymeric carrier for the preparation of organic-inorganic precursors. Titanium isopropoxide and calcium nitrate were dissolved in liquid-type ethylene glycol without any precipitation. At the optimum amount of the polymer, the metal cations were dispersed in solution and a homogeneous polymeric network was formed. The dried precursor ceramic gels were turned to porous powders through calcination process. The porous powders were crystallized at low temperatures and the crystalline powders were planetary milled to nano size.

• 한국표면공학회지
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• 제48권6호
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• pp.309-314
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• 2015

Multiwall carbon nanotubes are synthesized by using VLS mechanism for the application to $H_2$ gas sensor. MWCNT is not suitable for hydrogen gas sensor due to its low response to the gas. To enhance the gas sensing performance, multiwall carbon nanotubes are coated with $TiO_2$ nanoparticles. Scanning electron microscopy and Transmission electron microscopy showed that the synthesized MWCNT were well dispersed with the diameter and wall thickness of approximately 10-30nm and 5nm, respectively. The MWCNT sensor showed the sensitivities of 1.33-9.5% for the $H_2$ concentration of 100-5000ppm at room temperature. These sensitivities are significantly improved to 6.64-46.65% by coating $TiO_2$ nanoparticles to the MWCNT sensor. The mechanisms of $H_2$ gas sensing improvement of the MWCNT sensor coated with $TiO_2$ nanoparticles are discussed.

• 한국분말재료학회지
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• 제9권1호
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• pp.25-31
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• 2002

The efects of mechanical aloying conditions and the type of reducing agent on the solid state reductionof haematite $Fe_2O_3$ have been investigated at room temperature. Aluminium titanium zinc and copper were used as reducing agent. Nanocomposites of metal-oxide in which oxide particles with nano size were dispersed in Fe matrix were obtained by mechanical alloying of $Fe_2O_3$ with aluminium and titanium respectively However the reduction of $Fe_2O_3$ by coppe was not occurred Composite materials of iron with $Al_2O_3$ and $TiO_2$ were obtained from the system of $Fe_2O_3-Al$ and $Fe_2O_3-Ti$ after ball milling for 20 hrs and 30 hrs respectively. And the system of $Fe_2O_3-Zn$ resulted in the formationof FeO with ZnO after ball milling of 120 hrs. The final grain sizes of iron estimated by X-ray diffraction line-width measurement were in the ranges of 24~33 nm.

• Bulletin of the Korean Chemical Society
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• 제33권10호
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• pp.3355-3360
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• 2012

To promote the photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs), graphene is introduced as a working electrode with $TiO_2$ in this study, because it has great transparency and very good conductivity. XRD patterns indicate the presence of graphene and $TiO_2$ particles in graphene-linked $TiO_2$ samples. Moreover, TEM pictures also show that the nano-sized $TiO_2$ particles are highly dispersed and well-linked onto the thin layered graphene. On the basis of the UV-visible spectra, the band gaps of $TiO_2$, 1.0 wt % graphene-$TiO_2$, 5.0 wt % graphene-$TiO_2$, and 10.0 wt % graphene-$TiO_2$ are 3.16, 2.94, 2.25, and 2.11 eV, respectively. Compared to pure $TiO_2$, the energy conversion efficiency was enhanced considerably by the application of graphene-linked $TiO_2$ anode films in the DSSCs to approximately 6.05% for 0.1 wt % graphene-$TiO_2$ with N719 dye (10.0 mm film thickness and $5.0mm{\times}5.0mm$ cell area) under $100mW/cm^2$ of simulated sunlight. The quantum efficiency was the highest when 1.0 wt % of graphene was used. In impedance curves, the resistance was smallest for 1.0 wt % graphene-$TiO_2$-DSSC.

• 한국세라믹학회지
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• 제39권1호
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• pp.38-44
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• 2002

여러 종류의 전해질이 존재할 때, 수계 및 비수계 분산매체에서 저온균일침전법으로 제조된 침상형태의 일차입자를 갖는 나노 크기의 루틸상 TiO$_2$분말에 대한 분산 안정성을 조사하였다. 제타전위 측정은 수계 및 비수계 분산매체에 전해질 첨가가 TiO$_2$입자 표면의 전위 역전을 유발하는 것을 보여주었다. 비수계 분산매체에 분산되어 있는 TiO$_2$입자 사이에 작용하는 정전기적 반발력은 수계 분산매체에서보다 크게 관찰되었고, 이것은 점도, 유전 상수와 같은 유기 용매의 물리적 특성과 밀접한 연관이 있음을 알 수 있었다. pH, 전해질의 농도와 이온의 원자가는 TiO$_2$입자의 표면전위를 크게 변화시켰고, TiO$_2$입자의 분산 거동을 사실상 주도하였다.

• 한국군사과학기술학회지
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• 제18권2호
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• pp.139-145
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• 2015

In this paper, the flexible piezoelectric nanocomposite generator(NCG) device based on $BaTiO_3$ nanostructures was fabricated via simple and low-cost spin coating method. The $BaTiO_3$ nanostructures synthesized by self-assembly reaction showed dendrite morphologies. To produce the piezoelectric nanocomposite(p-NC layer) which acts as an electric energy source in NCG device, the piezoelectric nanopowders($BaTiO_3$) were dispersed in polydimethylsiloxane(PDMS). Sequently, the p-NC layer was inserted in two dielectric layer of PDMS; these layers enabled the NCG device flexibility as well as durability prohibiting detachment(exfoliation) for significantly mechanical bending motions. The fabricated NCG device shows average maximum open circuit voltage of 6.2 V and average maximum current signals of 300 nA at 20 wt% composition of $BaTiO_3$ nanostructures in p-NC layer. Finally, the flexible energy harvester generates stable output signals at any rate of frequency which were used to operate LCD device without any external energy supply.

• Advances in nano research
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• 제15권4호
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• pp.295-304
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• 2023

In this paper, a powerful photocatalyst based on carbon nanocomposite is developed in order to obtain a new material applicable in water treatment and especially for the discoloration of effluents used in the textile industry. For that, TiO₂-graphene nanocomposites have been successfully synthesized by a mixture of Functionalized Graphene Sheet (FGS) and tetrachlorotitanium complexes to form FGS-TiO₂ nanocomposite. In the presence of an anionic surfactant, we used a new chemical process to functionalize graphene sheets in order to make them an excellent medium for blocking and preventing the aggregation of TiO₂ nanoparticles. The components of these nanocomposites are characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which confirms the successful formation of the FGS-TiO₂ nanocomposite. It was found that the TiO₂ nanoparticles were dispersed uniformly on the graphene plane which possesses better charge separation capability than pure TiO₂. The FGS-TiO₂ nanocomposites exhibited higher photocatalytic activity compared to pure TiO₂ for the removal of three dyes: such as Methylene Blue (MB), Bromophenol Blue (BB) and Alizarin Red-S (AR) in water. The removal process was fast and more efficient with FGS-TiO₂ nanocomposite in daylight (in the absence of UV irradiation) compared to pure TiO₂ nanoparticles without and under UV in all pH range.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.444-444
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• 2008

For the polymer tandem cell, simple and advantaged solution-based method to electron transport intermediate layer is presented which are composed $TiO_2$ nanoparticles. Device were based on a regioregular Poly(3-hexylthiophene)(P3HT) and [6,6]-phenyl $C_{61}$ butyric acid methyl ester($PC_{60}BM$) blend as a donor and acceptor bulk-heterojunction. For the middle electrode interlayer, the $TiO_2$ nanoparticles were well dispersed in ethanol solution and formed thin layer on the P3HT:PCBM charge separation layer by spin coating. The layer serves as the electron transport layer and divides the polymer tandem solar cell. The open-circuit voltage (Voc) for the polymer tandem solar cells was closed to the sum of those of individual cells.

• 접착 및 계면
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• 제16권1호
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• pp.6-14
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• 2015

본 연구에서는 양친성 반응성 고분자 전구체를 합성하고 이를 사용하여 화학적, 물리적으로 안정한 코아 가교 양친성 고분자(Core-crosslinked Amphiphilic Polymer; 이하 CCAP) 나노입자를 제조하였으며, CCAP 나노입자를 $TiO_2$ 나노입자 제조의 템플레이트로 응용하였다. 먼저 CCAP 나노입자 수용액과 티타늄 이소프로폭사이드(Titanium isopropoxide)를 혼합하여, 매우 안정한 유/무기 나노하이브리드 솔(Sol)을 제조하였으며, 제조된 솔(Sol)은 회전코팅(Spin coating) 기법을 통해 유/무기 하이브리드 박막으로 제조하고, 소결 공정을 통해서 템플레이트인 CCAP를 제거하여 제조된 $TiO_2$ 나노입자의 미세구조를 주사전자현미경(SEM)을 이용하여서 관찰하였다. 다양한 CCAP 나노입자를 템플레이트로 사용하여 제조된 $TiO_2$ 나노입자의 미세구조를 기존 유기물 템플레이트(계면활성제)를 사용하여 제조된 $TiO_2$ 나노입자의 미세구조와 비교하여, CCAP 나노입자가 $TiO_2$ 나노입자 구조에 미치는 영향을 조사하였다.