• Journal of Electrochemical Science and Technology
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• 제1권2호
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• pp.117-120
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• 2010

Materials used as fuel cell electrode should be light, high conductive, high surface area for reaction, catalytic surface and uniformity of porous structure. Nickel is widely used in electrode materials because it itself has catalytic properties. When used as electrode materials, nickel of only a few im on the surface may be sufficient to conduct the catalytic role. To manufacture the nickel with porous structure, Electroless nickel plating on carbon fiber be conducted. Because electroless nickel plating is possible to do uniform coating on the surface of substrate with complex shape. Acidic bath and alkaline bathe were used in electroless nickel plating bath, and pH and temperature of bath were controlled. The rate of electroless plating in alkaline bath was faster than that in acidic bath. As increasing pH and temperature, the rate of electrolee plating was increased. The content of phosphorous in nickel deposit was higher in acidic bath than that in alkaline bath. As a result, the uniform nickel deposit on porous carbon fiber was conducted.

• Corrosion Science and Technology
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• 제21권5호
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• pp.412-417
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• 2022

Proton exchange membrane fuel cells (PEMFCs) provide zero emission power sources for electric vehicles and portable electronic devices. Although significant progresses for the widespread application of electrochemical energy technology have been achieved, some drawbacks such as catalytic activity, durability, and high cost of catalysts still remain. Pt-based catalysts are regarded as the most efficient catalysts for sluggish kinetics of oxygen reduction reaction (ORR). However, their prohibitive cost limits the commercialization of PEMFCs. Therefore, we proposed a NiCo@Au core shell structure as Pt-free ORR electrocatalyst in PEMFCs. NiCo alloy was synthesized as core to introduce ionization tendency and autoxidation reaction. Au as a shell was synthesized to prevent oxidation of core NiCo and increase catalytic activity for ORR. Herein, we report the synthesis, characterization, electrochemical properties, and PEMFCs performance of the novel NiCo@Au core-shell as a catalyst for ORR in PEMFCs application. Based on results of this study, possible mechanism for catalytic of autoxidation core@anti-oxidation shell in PEMFCs is suggested.

• Journal of Electrochemical Science and Technology
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• 제15권3호
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• pp.345-352
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• 2024

The synthesis of Pt nanoparticles and catalytically active materials using the electrochemical top-down approach involves dispersing Pt electrodes in an electrolyte solution containing alkali metal cations and support material powder using an alternating pulsed current. Platinum is dispersed to form particles with a predominant crystallographic orientation of Pt(100) and a particle size of approximately 7.6±1.0 nm. The dispersed platinum particles have an insignificant content of PtO_x phase (0.25±0.03 wt.%). The average formation rate was 9.7±0.5 mg cm^-2 h^-1. The nature of the support (carbon material, metal oxide, carbon-metal oxide hybrid) had almost no effect on the formation rate of the Pt nanoparticles as well as their crystallographic properties. Depending on the nature of the support material, Pt-containing catalytic materials obtained by the electrochemical top-down approach showed good functional performance in fuel cell technologies (Pt/C), catalytic oxidation of CO (Pt/Al₂O₃) and electrochemical oxidation of methanol (Pt/TiO₂-C) and ethanol (Pt/SnO₂-C).

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권4호
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• pp.201-208
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• 2000

The reduction of NO by hydrocarbons was investigated over Cu/Al$_2$O$_3$catalysts using a stainless steel flow reactor under highly oxidising diesel exhaust conditions(up to 15%). Three different Cu loadings(1,5 and 10wt.%) on an $Al_2$O$_3$support were prepared and characterized using spectroscopic techniques. The catalytic activity tests show that different Cu loadings as well as temperature, oxygen, and hydrocarbon concentration levels significantly influence the NO reduction. Increasing Cu loadings up to 5 and 10wt.% decreases the catalytic activities for NO reduction due to the formation of a bulk crystalline CuO phase, as observed from XRD and SEM images. In particular, the visualization of the copper dispersion on the surface using the SEM-BEI technique provides information on the extent of copper saturation, particle size, and the effects on NO reduction. However, the lower Cu loading(1 wt.%) increases the catalytic activity with a temperature window of 720-810K, thereby favoring the formation of well dispersed isolated Cu species, e.g. Cu(sup)2+ ions, which is related to selective NO reduction. The effects of other reaction parameters, such as oxygen, the hydrocarbon level and type, and byproduct emissions are further discussed.

• 한국분말재료학회지
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• 제8권3호
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• pp.197-200
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• 2001

Modified inert gas condensation method was used to produce the nanocluster composites of $CuO/CeO_2$. High-resolution TEM, SEM and catalytic measurements have been used to characterize the samples and study the synergistic effect between the CuO phase and $CeO_2$(ceria) support. By varying the He pressure, the heating temperature and configuration of the heating boats inside the modified gas condensation chamber, nanoclusters of varying sizes, shapes and composition can be produced. The composition and nanostructured morphology were shown to influence the catalytic properties of the system. A copper content around 10 at% with a morphology that favors high-energy surfaces of ceria is shown to be beneficial for a high catalytic activity.

• 한국대기환경학회지
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• 제20권4호
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• pp.451-463
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• 2004

The performance of disk-type catalytic filters impregnated by TiO$_2$ or TiO$_2$-3Al$_2$O$_3$ㆍ 2SiO$_2$ supports and V$_2$O$_{5}$ catalyst was evaluated for selective catalytic reduction (SCR) of NO with ammonia as a reductant. XRD, FT -IR, BET and SEM were used to characterize the catalytic filters prepared in this work. Optimal V$_2$O$_{5}$ loading and reaction temperature for V$_2$O$_{5}$/TiO$_2$ catalytic filters were 3-6 wt.% and 350-40$0^{\circ}C$ at GHSV 14,300 $hr^{-1}$ in the presence of oxygen, respectively. With increasing the V$_2$O$_{5}$ loading from 0.5 to 6 wt%, NO conversion increased from 24 to 96% at 40$0^{\circ}C$ and 14.300$hr^{-1}$, and maintained at 80% over in the V$_2$O$_{5}$ loading range of 3-6 wt.% and then dropped at V$_2$O$_{5}$ loading of 7wt.% over. In comparing V$_2$O$_{5}$/ TiO$_2$ and V$_2$O$_{5}$/ TiO$_2$-3Al$_2$O$_3$ㆍ2SiO$_2$ catalytic fillers, which have same 3wt.% V$_2$O$_{5}$ loading, the V$_2$O$_{5}$/ TiO$_2$-3A1$_2$O$_3$ㆍ2SiO$_2$ catalytic filter showed higher activity than V$_2$O$_{5}$/ TiO$_2$ catalytic filter, but higher differential pressure drops owing to its low air permeability. low air permeability.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1378-1379
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• 2006

Carbon nanotubes (CNTs) with few defects and very small amount of amorphous carbon coating have been synthesized by catalytic decomposition of acetylene in $H_2$ over well-dispersed metal particles supported on MgO. The yield, quality and diameters of CNTs were obtained by control of catalyst metal compositions to be used. The optimization condition of carbon nanotubes with high yield is when Co and Mo are in a 1:1 ratio and Fe metal contents to Co is increased on magnesium oxide support. It is also found that the diameter of the as-prepared CNTs can be controlled mainly by adjusting the molar ratio of Fe-Mo, Co-Fe, and Co-Mo versus the MgO support. Our results indicated that desired diameter distribution of CNTs is obtained by choosing or combining the catalyst to be employed.

• 청정기술
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• 제20권1호
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• pp.28-34
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• 2014

본 연구에서는 나노 크기의 결정 구조를 가진 타이타니아 담체를 용매열합성법(solvothermal method)을 활용하여 합성한 후 팔라듐과 구리를 담지한 촉매를 제조하였다. 제조된 촉매를 수중 질산성 질소 저감 반응에 적용한 결과, 타이타니아 담체의 결정 크기가 반응 활성에 영향을 미치는 것이 확인되었다. 결정 크기가 작은 담체를 활용한 촉매가 더 빠른 속도로 질산성 질소를 저감하였지만, 반응 중 pH가 높게 형성되어 질소 선택도가 매우 낮은 현상을 보였다. 이를 해결하기 위해 pH 완충제인 이산화탄소를 공급하여 질소 선택도를 약 60% 증가시켰다. 상기에 언급한 촉매를 대상으로 질소 흡-탈착, X-ray diffraction (XRD), $H_2$-temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) 등의 다양한 특성화 분석을 수행하여 촉매의 반응활성과 물성간의 상관관계에 대해 조사하였다.

• 대한화학회지
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• 제55권1호
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• pp.81-85
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• 2011

이소부탄의 산화탈수소반응(ODH)에 대한 $V_{0.9}Sb_{0.1}O_x$ 촉매계의 5가지 담지체의 촉진효과를 조사하였다. 사용된 5가지 담지체는 감마-알루미나, 알파-알루미나, 실리카-알루미나, 실리카겔, 마그네슘 산화물이다. 촉매는 사용된 담지체에 따라 그 효과가 다르게 나타났다: ${\gamma}-Al_2O_3$ > $\alpha$-$Al_2O_3$ > Si-Al-O> $SiO_2$ $\approx$MgO$\gg$unsupported. V-Sb-O 비율은 별로 촉매 활성과 선택성에 영향을 미치지 않았다. 촉매 성분들이 담지체에 골고루 잘 분포된 이유로 인해 감마-알루미나에 담지된 $V_{0.9}Sb_{0.1}O_x$ 촉매계가 성능이 제일 뛰어났다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.58-61
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• 2009

추진제로써 아산화질소를 활용하기 위해 아산화질소의 촉매 분해 특성에 대한 연구를 수행하였다. 아산화질소를 분해하기 위해 Ru와 Pt 촉매를 $Al_2O_3$ 지지체에 함침법을 이용하여 담지하였고, 관형 반응기를 사용하여 GHSV와 반응온도에 따른 아산화질소의 전환율을 측정하였다. GHSV는 낮을수록, 반응온도는 높을수록 전환율이 높았고, Ru/$Al_2O_3$ 촉매가 Pt/$Al_2O_3$ 촉매보다 우수한 성능을 보였다.