• 공업화학
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• 제17권4호
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• pp.369-374
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• 2006

Ethyl pyruvate의 비대칭 수소화 반응에 $Rh-Pt/Al_{2}O_{3}$ 이원금속 촉매를 처음으로 적용하고 그 반응특성을 조사하였다. $Rh-Pt/Al_{2}O_{3}$ 촉매는 상용 $Pt/Al_{2}O_{3}$에 Rh을 담지하거나 $Al_{2}O_{3}$에 Pt와 Rh을 연속적으로 함침시켜 제조하여, 촉매제법, Rh 함량 및 환원온도에 따라 반응속도, 광학선택도(ee%)가 변화하는 경향을 비교하였으며, XRD, TEM을 통하여 촉매의 물리적 특성을 분석하였다. $Rh-Pt/Al_{2}O_{3}$ 이원금속 촉매는 환원온도가 증가함에 따라 반응속도와 광학순도가 향상되었다(63.6 ee%). 또한 Rh의 함량에 따라서도 촉매 반응속도의 큰 변화를 보여주었는데, 그 변화 경향은 촉매 제조과정에 따라 달랐으나 광학선택도는 모든 이원촉매가 단일촉매에 비해 떨어지는 결과(56~60 ee%)를 나타내었다.

• Carbon letters
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• 제10권3호
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• pp.213-216
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• 2009

The electrochemical deposition of Pt nanoparticles on carbon nanotubes (CNTs) supports and their catalytic activities for methanol electro-oxidation were investigated. Pt catalysts of 4~12 nm average crystalline size were grown on supports by potential cycling methods. Electro-plating of 12 min time by potential cycling method was sufficient to obtain small crystalline size 4.5 nm particles, showing a good electrochemical activity. The catalysts' loading contents were enhanced by increasing the deposition time. The crystalline sizes and morphology of the Pt/support catalysts were evaluated using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrochemical behaviors of the Pt/support catalysts were investigated according to their characteristic current-potential curves in a methanol solution. In the result, the electrochemical activity increased with increased plating time, reaching the maximum at 12 min, and then decreased. The enhanced electroactivity for catalysts was correlated to the crystalline size and dispersion state of the catalysts.

• 한국수소및신에너지학회논문집
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• 제23권6호
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• pp.654-659
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• 2012

The interest in water gas shift (WGS) reaction has grown significantly, as a result of the recent advances in fuel cell technology and the need to develop small-scale fuel processors. Recently, researchers have tried to overcome the disadvantages of the commercial WGS catalysts. As a consequence, supported Pt catalysts have attracted a lot of researchers due to high activity and stability for WGS at low temperatures. In this study, $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts with various Ce/Zr ratio have been applied to WGS at a gas hourly space velocity (GHSV) of $45,515h^{-1}$. According to TPR patterns of $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts, the reducibility increases with decreasing the $ZrO_2$ content. As a result, Cubic structure $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts exhibited higher CO conversion than tetragonal structure $Pt-Na/Ce_{(1-x)}Zr_{(x)}O_2$ catalysts. Expecially, Pt-Na/$CeO_2$ exhibited the highest CO conversion as well as 100% selectivity to $CO_2$. Moreover, Pt-Na/$CeO_2$ catalyst showed relatively stable activity with time on stream. The high activity of cubic structure Pt-Na/$CeO_2$ catalyst was correlated to its higher oxygen storage capacity (OSC) of $CeO_2$ and easier reducibility of Pt/$CeO_2$.

• 한국입자에어로졸학회지
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• 제8권2호
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• pp.69-74
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• 2012

This study describes how successfully a conventional flame aerosol synthesis was used to continuously synthesize Pt-Ru catalysts supported by carbon agglomerates. Nearly spherical catalysts produced in the flame were mainly composed of metallic Pt and Ru with the molar ratio of 1:1 and those sizes were controllable from ~1.5 nm to ~2.0 nm. Nevertheless, only Pt peaks were found from X-ray diffraction experiments, suggesting that amorphous-like Ru was well mixed in the crystalline Pt lattices. It was found from Cyclo-voltamograms and CO stripping experiments that the electrochemical properties of the catalysts are at least comparable to that of a conventional commercial sample.

• 반도체디스플레이기술학회지
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• 제7권4호
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• pp.45-49
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• 2008

For the commercialization of polymer electrolyte membrane fuel cell (PEMFC), some serious problems such as the decrease of platinum use as catalysts and a larger overpotential of oxygen reduction reaction (ORR) at cathode must be solved. In this study, 20%Pt/C and 20%PtCo/C catalysts for the cathode of PEMFC were synthesized from the chemical reduction method and evaluated using an electrochemical measurement. The ORR activity of synthesized 20%Pt/C and 20%PtCo/C had higher than that of the 20%Pt/C on the market. The synthesized 20%PtCo/C with the cobalt concentration (Pt:Co atomic ratio) from 5 to 20% showed the highest ORR activity.

• 분석과학
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• 제18권2호
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• pp.130-138
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• 2005

VOCs (Volatile Organic Compounds)는 대기오염의 주원인으로서 인식되어왔다. 촉매산화는 저온에서 높은 효율을 나타내기 때문에 VOCs 제거를 위한 가장 중요한 처리기술중 하나이다. 이 연구에서는 $TiO_2$ 담체에 Pt, Ir 그리고 Pt-Ir을 담시지켜 촉매를 제조하였다. 반응물로서 Xylene을 사용하였다. 단일 또는 두 가지 이상의 촉매들은 함침법에 의해 준비하였고, X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), transmittence electron microscophy (TEM) 분석을 통하여 특성화하였다. 그 결과 Pt 촉매는 Ir 촉매에 비해 더 높은 전환율을 나타내었고, Pt-Ir 촉매는 가장 높은 전환율을 나타내었다. VOCs 산화에서, Pt-Ir 촉매는 다양한 활성점을 나타내었고 그것은 Pt의 metal 영역을 강화시켰다. 따라서 두 가지 금속으로 이루어진 촉매가 단일 금속으로 이루어진 촉매에 비해 VOCs 전환율이 더 높았다. 동역학적으로 VOCs 산화는 1차 반응이다. 이 연구에서 Pt에 Ir을 소량 첨가함으로써 VOCs 산화반응에 효과적이었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.296-298
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• 2005

Hydrogen generation by the hydrolysis of aqueous sodium borohydride $(NaBH_4)$ solutions was studied using IRA-400 anion resin dispersed Pt. Ru catalysts and Lithium Cobalt oxide $(LiCoO_2)$ supported Pt, Ru and PtRu catalysts. The performance of the $LiCoO_2$ supported catalysts is better than the ion exchange resin dispersed catalysts. There is a marked concentration dependence on the performance of the $LiCoO_2$ supported catalysts and the hydrogen generation rate goes down if the borohydride concentration is increased beyond $10\%$. The efficiency of PtRu- $LiCoO_2$ is almost double that of either Ru-$LiCoO_2$ or Pt-$LiCoO_2$ for $NaBH_4$ concentrations up to $10\%$.

• 공업화학
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• 제7권4호
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• pp.661-669
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• 1996

NaY 제올라이트에 Pt/Rh비를 달리하여 이온교환법으로 제조한 Pt-Rh촉매의 특성을$^{129}Xe$-NMR과 EXAFS 방법으로 특성조사를 하였다. $^{129}Xe$-NMR과 EXAFS 자료는 PtRh 이원금속 클러스터의 표면으로 Rh 원자들이 모이는 것으로 나타났다. 모사 자동차 배기가스를 사용하여 희박, 과농 및 양론조건에서 CO, HC 및 $NO_x$ 전환율을 측정하였으며, Pt-Rh/NaY(Pt/Rh=1) 이원금속 촉매가 다른 촉매들보다 세가지 오염물질에 대한 반응활성이 높게 나타남을 알 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제6권3호
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• pp.95-105
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• 2015

In the present work, Carbon supported Pt₁₀₀, Pt₈₀Sn₂₀, Pt₈₀Ni₂₀ and Pt₈₀Sn₁₀Ni₁₀ electrocatalysts with different atomic ratios were prepared by ethylene glycol-reduction method to study the electro-oxidation of ethanol in membraneless fuel cell. The electrocatalysts were characterized in terms of structure, morphology and composition by using XRD, TEM and EDX techniques. Transmission electron microscopy measurements revealed a decrease in the mean particle size of the catalysts for the ternary compositions. The electrocatalytic activities of Pt₁₀₀/C, Pt₈₀Sn₂₀/C, Pt₈₀Ni₂₀/C and Pt₈₀Sn₁₀Ni₁₀/C catalysts for ethanol oxidation in an acid medium were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results showed that addition of Ni to Pt/C and Pt-Sn/C catalysts significantly shifted the onset of ethanol and CO oxidations toward lower potentials. The single membraneless ethanol fuel cell performances of the Pt₈₀Sn₁₀Ni₁₀/C, Pt₈₀Sn₂₀/C and Pt₈₀Ni₂₀/C anode catalysts were evaluated at room temperature. Among the catalysts investigated, the power density obtained for Pt₈₀Sn₁₀Ni₁₀/C (37.77 mW/cm² ) catalyst was higher than that of Pt₈₀Sn₂₀/C (22.89 mW/cm² ) and Pt₈₀Ni₂₀/C (16.77 mW/ cm² ), using 1.0 M ethanol + 0.5 M H₂SO₄ as anode feed and 0.1 M sodium percarbonate + 0.5 M H₂SO₄ as cathode feed.

• 한국재료학회지
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• 제21권3호
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• pp.180-185
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• 2011

This study is aimed to increase the activity of cathodic catalysts for PEMFCs(Polymer Electrolyte Membrane Fuel Cells). we investigated the temperature effect of 20wt% Pt/C catalysts at five different temperatures. The catalysts were synthesized by using chemical reduction method. Before adding the formaldehyde as reducing agent, process was undergone for 2 hours at the room temperature (RT), $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ and $100^{\circ}C$, respectively. The performances of synthesize catalysts are compared. The electrochemical oxygen reduction reaction (ORR) was studied on 20wt% Pt/C catalysts by using a glassy carbon electrode through cyclic voltammetric curves (CV) in a 1M H2SO4 solution. The ORR specific activities of 20wt% Pt/C catalysts increased to give a relative ORR catalytic activity ordering of $80^{\circ}C$ > $100^{\circ}C$ > $60^{\circ}C$ > $40^{\circ}C$ > RT. Electrochemical active surface area (EAS) was calculated with cyclic voltammetry analysis. Prepared Pt/C (at $80^{\circ}C$, $100^{\circ}C$) catalysts has higher ESA than other catalysts. Physical characterization was made by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The TEM images of the carbon supported platinum electrocatalysts ($80^{\circ}C$, $100^{\circ}C$) showed homogenous particle distribution with particle size of about 2~3.5 nm. We found that a higher reaction temperature resulted in more uniform particle distribution than lower reaction temperature and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.