• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.917-923
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• 2005

In this paper, effect of catalytic configuration on the sensing properties of $SnO_2$ nanoparticle gas sensitive thick film was investigated. Two types of catalytic configuration, mono and binary, were made on the $SnO_2$ nanoparticle. In case of mono catalytic system, $3 wt\%$ Pd or Pt catalyst was doped onto the $SnO_2$ nanoparticle, respectively. In case of binary catalytic system, Pd and Pt was doped simultaneously with concentration ratio of 1:2 to 2:1 onto the $SnO_2$ nanoparticle. After doping, gas sensitive thick film was printed on alumina substrate and heat-treated at 450 to $600^{\circ}C$. Gas sensing properties was evaluated using 500 to 10,000 ppm $CH_4$ gas. As a result, gas sensitive thick film with binary catalytic system showed unstable phenomena that the gas sensitivity was changed according to aging time. In contrary, the mono catalytic system showed relatively stable phenomena despite of aging time. Especially, gas sensitive thick film doped with $3 wt\%$ Pt catalyst and heat-treated at $500^{\circ}C$ showed good sensing properties such as 0.57 of $R_{3500}/R_{1000}$ and very small variation within $3.5\%$ after aging for 5 hours, and response time was very short less than 20 seconds.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.247-252
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• 2004

노튜브의 길이는 급격히 증가하였지만 촉매금속의 적층방법에 따른 탄소나노튜브의 성장 형태는 큰 차이가 없었다. 특히, ICBD 방법에 의해 Ni 촉매금속을 증착한 경우 다른 방법에 비하여 직선적인 탄소나노튜브가 관찰되었다. ^x Carbon nanotubes were grown on SiO$_2$/Si substrates by applying $C_2$H$_2$ gas through chemical vapor deposition process. It was found that carbon nanotubes were grown successfully on the substrates with catalytic films under 20 $\AA$ total thickness. The increase in reaction temperature from 50$0^{\circ}C$ to 80$0^{\circ}C$ resulted in longer carbon nanotube, but there was no clear tendencies with different types of catalytic layers. It was evident that carbon nanotubes became more straight on the substrate with Ni catalytic film produced by ICBD method.

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.83-88
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• 2003

PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.291.2-291.2
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• 2013

Growth behavior of b-Ga2O3 nanowires (NWs) on sapphire(0001) substrates during radio-frequency magnetron sputtering is reported. Upon fabrication, flat thin films grew initially, subsequent to which, NW bundles were formed on the surface of thin film with increasing film thickness. This transition of the growth mode occurred only at temperatures greater than ${\sim}450^{\circ}C$. The b-Ga2O3 NWs were grown through the self-catalytic vapor-liquid-solid mechanism with self-assembled Ga seeds. Secondary growth of NWs, which occurred from the sides of primary NWs resulting in branched NW structures, was also observed. Finally, the room temperature photoluminescence properties of as-grown and annealed b-Ga2O3 NW samples were investigated.

• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.178-182
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• 2008

Planar type micro catalytic combustible gas sensor was developed by using nano crystalline $SnO_2$ Pt thin film as micro heater was deposited by thermal evaporation method on the alumina substrate. The thickness of the Pt heater was around 160 nm. The sensor showed high reliability with prominent selectivity against various gases(Co, $C_3H_8,\;CH_4$) at low operating temperature($156^{\circ}C$). The sensor with nano crystalline $SnO_2$ showed higher sensitivity than that without nano crystalline $SnO_2$. This can be explained by more active adsorption and oxidation of hydrogen by nano crystalline $SnO_2$ particles. The present planar-type catalytic combustible hydrogen sensor with nano crystalline $SnO_2$ is a good candidate for detection of hydrogen leaks.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.910-914
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• 2018

Since catalyst technology is one of the promising technologies to improve the working performance of next generation energy and electronic devices, many efforts have been made to develop various catalysts with high efficiency at a low cost. However, there are remaining challenges to be resolved in order to use the suggested catalytic materials, such as platinum (Pt), gold (Au), and palladium (Pd), due to their poor cost-effectiveness for device applications. In this study, to overcome these challenges, we suggest a useful method to increase the surface area of a noble metal catalyst material, resulting in a reduction of the total amount of catalyst usage. By employing block copolymer (BCP) self-assembly and nano-transfer printing (n-TP) processes, we successfully fabricated sub-20 nm Pt line and cross-bar patterns. Furthermore, we obtained a highly ordered Pt cross-bar pattern on a Ni thin film and a Pt-embedded Ni thin film, which can be used as hetero hybrid alloy catalyst structure. For a detailed analysis of the hybrid catalytic material, we used scanning electron microscope (SEM), transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDS), which revealed a well-defined nanoporous Pt nanostructure on the Ni thin film. Based on these results, we expect that the successful hybridization of various catalytic nanostructures can be extended to other material systems and devices in the near future.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.70-73
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• 2015

Many studies have used chemical vapor deposition (CVD) to grow graphene. However, CVD is inefficient in terms of production costs, and inefficient for mass production because a transfer process using a catalytic metal is needed. In this study, graphene thin films were grown on single crystal sapphire substrates without a catalytic metal, using pulsed laser deposition (PLD) to resolve these problems. In addition, the growth of graphene using PLD was confirmed to have a close relationship with the substrate temperature.

• Journal of Power System Engineering
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• v.4 no.2
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• pp.31-39
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• 2000

Relationships between the plating condition and the plating rate of the deposition film for the electroless plating of Co-Cu-P alloy were discussed in this report. The result obtained from this experiment were summarized as follow ; The optimum bath composition was consisted of 0.8 ppm thiourea as a stabilizing agent. Composition of the deposit was found to be uniform after two hours of electroless plating. Plating rates of nickel-catalytic surface and zincate-catalytic surface were found to be very closely equal, but the plating time of nickel-catalytic surface took longer than that of the zincated-catalytic surface.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.2105-2110
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• 2013

Carbon-fiber-supported NiO catalytic filters for oxidation of volatile organic compounds were prepared by electroless Ni-P plating and subsequent annealing processes. Surface structure and crystallinity of NiO film on carbon fiber could be modified by post-annealing at different temperatures (500 and $650^{\circ}C$). Catalytic thermal decompositions of toluene over these catalytic filters were investigated. $500^{\circ}C$-annealed sample showed a higher catalytic reactivity toward toluene decomposition than $650^{\circ}C$-annealed one under same conditions, despite of its lower surface area and toluene adsorption capacity. X-ray diffraction and X-ray photoelectron spectroscopy studies suggest that amorphous structures of NiO on $500^{\circ}C$-annealed catalyst caused the higher reactivity for oxidation of toluene than that of $650^{\circ}C$-annealed sample with a higher crystallinity.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.217-217
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• 2013

Carbon-fiber-supported NiO catalytic filters for oxidation of volatile organic compounds were prepared by electroless Ni-P plating and subsequent annealing processes. Surface structure and crystallinity of NiO film on carbon fiber could be modified by post-annealing at different temperatures (500 and $650^{\circ}C$. Catalytic thermal decompositions of toluene over these catalytic filters were investigated. $500^{\circ}C$ annealed sample showed a higher catalytic reactivity toward toluene decomposition than $650^{\circ}C$ annealed one under same conditions, despite of its lower surface area and toluene adsorption capacity. X-ray diffraction and X-ray photoelectron spectroscopy studies suggested that amorphous structures of NiO on $500^{\circ}C$ annealed catalyst caused the higher reactivity for oxidation of toluene than that of $650^{\circ}C$ annealed sample with a higher crystallinity.