• 대한금속재료학회지
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• 제47권2호
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• pp.91-98
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• 2009

The titania nanotubular layer for photocatalytic application was synthesized by anodization process in HF solution and the photocatalytic efficiencies of nanotubular film were evaluated by the decomposition rate of aniline blue. In order to facilitate the photocatalytic reaction, the electron acceptors such as potassium bromate, hydrogen peroxide and ammonium persulfate were added to aniline blue solution and the effects of electron acceptors on the dye degradation efficiency were evaluated. The results showed that the photocatalytic efficiency has markedly improved by adding the electron acceptors.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.267-273
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• 2012

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber-the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam-was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
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• pp.80-86
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• 2011

Solar reforming of methane with CO2 was successfully tested with a direct irradiated absorber on a parabolic dish capable of 5kWth solar power. And the new type of double-layer absorber - the front layer, porous metal foam which absorbs the radiation and transfers the heat from material to gas, and the back layer, catalytically-activated metal foam - was prepared, and its activity was tested by using electric furnace. Ni was applied as the active metal on the gamma-Al2O3 coated Ni metal foam for the preparation of the catalytically-activated metal foam layer. Compared to conventional direct irradiation of the catalytically activated metal foam absorber, this new type of double layer absorber is found to exhibit a superior reaction and thermal storage performance at the fluctuating incident solar radiation. In addition, unlike direct irradiation of the foam absorber, double layer absorber has better thermal resistance, which prevents the emergence of cracks caused by mechanical or thermal shock. The total solar power absorbed reached up to 3.25kW and the maximum CH4 conversion was almost 59%.

• 한국진공학회지
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• 제16권3호
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• pp.187-191
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• 2007

본 연구에서는 실리콘 웨이퍼 위에 마그네트론 스퍼터링 시스템을 이용하여 Ni 촉매 층을 증착시키고, $NH_3$와 $C_2H_2$ gas를 이용하여 탄소나노튜브를 성장시켰다. Hot-filament 플라즈마 화학기상 증착법으로 탄소나노튜브의 성장 온도는 350, 450, 550, $650^{\circ}C$로 변화시켰으며, 성장되어진 탄소나노튜브는 field emission scanning electron microscope(FESEM) 분석을 하여 관찰하였고, 접촉각 측정법을 이용하여 탄소나노튜브 층의 특성을 분석하였다. 결과적으로 성장 온도는 탄소나노튜브의 성장 특성을 변화시키는 중요한 요소이다.

• 한국전기전자재료학회논문지
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• 제22권4호
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• pp.342-349
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• 2009

This study investigated the growth characteristics of carbon nanotubes (CNTs) by changing a period of annealing time and a $C_{2}H_{2}/H_2$ flow ratio at temperature as low as $450^{\circ}C$ with inductively coupled plasma chemical vapor deposition. The 1-nm-thick Fe-Ni-Co alloy thin film served as a catalyst layer for the growth of CNTs, which was thermally evaporated on the 15-nm-thick Al underlayer deposited on the 50-nm-thick Ti diffusion barrier. The annealing at low temperature of $450^{\circ}C$ brought about almost no granulation of the catalyst layer, and the CNT growth was not affected by a period of annealing time. A study of changing the flow rate of $C_{2}H_{2}$ and $H_2$ showed that as the ratio of the $C_{2}H_{2}$ flow rate to the $H_2$ flow rate was lowered, the CNTs were grown to be longer With further decreasing the flow ratio, the length of CNTs reached the maximum and then became shorter. Under the optimized gas flow rates, we successfully synthesized CNTs with a uniform length over a 4-inch Si wafer at $450^{\circ}C$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.197-197
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• 2011

In this study, in contrast with cases in which Scanning Tunneling Microscopy (STM) tip-induced reactions were instigated by the tunneling electrons, the local electric field, or the mechanical force between a tip and a surface, we found that the tungsten oxide (WO3) covered tungsten (W) tip of a STM acted as a chemical catalyst for the S-H dissociative adsorption of phenylthiol and 1-octanethiol onto a Ge(100) surface. By varying the distance between the tip and the surface, the degree of the tip-catalyzed adsorption could be controlled. We have found that the thiol head-group is the critical functional group for this catalysis and the catalytic material is the WO3 layer of the tip. After removing the WO3 layer by field emission treatment, the catalytic activity of the tip has been lost. 3-mercapto isobutyric acid is a chiral bi-functional molecule which has two functional groups, carboxylic acid group and thiol group, at each end. 3-Mercapto Isobutyric Acid adsorbs at Ge(100) surface only through carboxylic acid group at room temperature and this adsorption was enhanced by the tunneling electrons between a STM tip and the surface. Using this enhancement, it is possible to make thiol group-terminated surface where we desire. On the other hand, surprisingly, the WO3 covered W tip of STM was found to act as a chemical catalyst to catalyze the adsorption of 3-mercapto isobutyric acid through thiol group at Ge(100) surface. Using this catalysis, it is possible to make carboxylic acid group-terminated surface where we want. This functional group-selective adsorption of bi-functional molecule using the catalysis may be used in positive lithographic methods to produce semiconductor substrate which is terminated by desired functional groups.

• 공업화학
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• 제8권6호
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• pp.927-933
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• 1997

알칼리형 연료전지용 라니니켈 수소극에서 카본블랙이 전극 성능 및 촉매층 구조에 미치는 영향을 전기화학적 방법과 질소 흡착법등을 이용하여 조사되었다. 본 연구에서 라니니켈 수소극 촉매층의 최적 카본블랙 함량은 2wt% 였다. 카본블랙의 첨가는 한계전류밀도를 증가시켰으며, 이는 기액접촉면적의 증가에 기인한 것으로 사료된다. 또한 한계전류밀도에서의 속도결정단계는 수소가 기액접촉면에서녹는 단계일 가능성이 높은 것으로 조사되었다.

• Composites Research
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• 제13권4호
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• pp.33-41
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• 2000

본 연구에서는 촉매지지체의 내구성과 내산화성을 향상시키기 위해 활성탄소에 SiC층을 형성하는 것에 관한 수치모사가 수행되었다. 이염화이메틸규소(DDS)로부터 탄화규소를 활성탄소 기공의 내부에 침투 증착시켜 기공성 구조를 유지하면서 활성탄소에 SiC층이 형성된다. 여러 다른 증착 조건에서 모사된 탄화규소의 물성을 연구함으로써 지지체 제조의 최적 증착 조건을 결정하였다. 정상상태하의 등온 반응기 안에서 대류, 확산 및 반응을 모사하여 시간의 경과에 따른 증착량, 기공 반경, 표면적의 변화 등을 구하였다. DDS의 농도가 낮고 반응압력이 작을수록 시료 기공내에 고른 증착이 얻어졌다. 또한 기공내부 증착에서 입자외부 표면 증착으로 바뀌므로 기공직경과 표면적들이 어느 시점에서 변곡점을 갖는 것이 관찰되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.48-48
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• 2009

최근 나노광전소자 응용에 큰 관심을 받는 물질인 산화물 나노선은 앞으로 불어 올 나노소재 시대를 여는 선두 물질이다. 이러한 산화물 나노선 가운데 가장 큰 관심을 받는 물질로는 산화아연 나노선을 들 수 있다. 삼화아연 나노선은 상온에서 큰 엑시톤 결합에너지 및 큰 밴드갭을 가지고 있으며 투명성 및 소자구동시 안정성을 지니고 있어 그 응용이 기대된다. 하지만 이러한 나노선을 이용한 광전소자 응용은 bottom-up 방식을 기초로 한 대면적 소자제작이 어렵다. 이러한 bottom-up 방식의 나노소자 제작에서 필요한 나노선 성장기술은 금속 catalyst 없이 대면적 성장, 나노선 수직어레이, 나노선의 고온성장, 기판 사이에 발생하는 자발적 계면층 제거 등으로 대표된다. 또한 나노선의 결정성 및 광특성 향상을 위해서는 고온성장이 불가피한데, 실리콘 기판과 같이 격자상수 불일치도가 큰 기판에서는 나노선 성장이 이루어지지 않고 다시 탈착되어 구조물이 성장되지 않는다. 본 연구에서는 선택적 삼원계 단결정 씨앗층을 이용하여 길이/직경 비가 매우 향상된 MgZnO 나노와이어를 interfacial layer 없이 수직으로 고온에서 성장하여 산화물 전계방출 에미터로서의 가능성을 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.160-160
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• 2011

In the present work, $TiO_2$ fiilms supported by porous silica gel with high surface area synthesized by atomic layer deposition(ALD). Porous structure of silica substrate could be maintained even after deposit large amount of $TiO_2$ (500 cycles of ALD process), suggesting the differential growth mode of $TiO_2$ on top surface and inside the pore. All the $TiO_2$-covered silica samples showed improved MB adsorption abilities, comparing to bare one. In addition, when silica surface was covered with $TiO_2$ films, MB adsorption capacity was almost fully recovered by re-annealing process (500$^{\circ}C$, for 1 hr, in ambient pressure), whereas MB adsorption capacity of bare silica was decreased after re-heaing process. FT-IR study demonstrated that $TiO_2$ film could prevent deposition of surface-bound intermediate species during thermal decomposition of adsorbed MB molecules. Photocatalytic activity of $TiO_2$/silica sample was also investigated.