• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.159-159
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• 2009

In this work, nitrogen and oxygen functionalities was introduced to the graphite nanofibers (GNFs) and their effect on electrocatalytic performance of the GNF supports for direct methanol fuel cells (DMFCs) was invesigated. The nitrogen and oxygen groups were introduced through the urea treatments and acid treatment, respectively. And, PtRu catalysts deposited on modified GNFs were prepared by a chemical reduction method. The catalysts were characterized by means of elemental analysis, nitrogen adsorption, and X-ray photoelectron spetroscopy (XPS). The structure and morphological characteristics of the catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). As a result, the Pt-Ru nanoparticles were impregnated on GNFs with good formation in 3-5 nm. And, the cyclic voltammograms for methanol oxidation revealed that the methanol oxidation peak varied depending on changes of surface functional groups. It was thus considered that the PtRu deposition was related to the reduction of PtRu and surface characteristics of the carbon supports. The changes of surface functional groups were related to PtRu reduction, significantly affect the methanol oxidation activity of anode electrocatalysts in DMFCs.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.97.2-97.2
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• 2011

Pt-Ru and Pt-Ni bimetallic catalysts were prepared and tested for heavy hydrocarbon reforming. Metals were supported on CGO($Ce_{0.8}Gd_{0.2}O_{2.0-x}$) by incipient wetness method. The prepared catalysts were characterized by Temperature programmed reduction(TPR). Oxidative steam reforming of n-dodecane was conducted to compare the activity of the catalysts. The reforming temperature was varied from $500^{\circ}C$ to $800^{\circ}C$ at fixed $O_2$/C of 0.3, $H_2O$/C of 3.0 and GHSV of 5,000/h.Reduction peaks of metal oxide, surface CGO and bulk CGO were detected. Reduction temperature of metal oxide decreased over the bi-metallic catalysts. It is considered that interaction between metals leads to decrease interaction between metal and oxygen. On the other hands, reduction temperatures of surface CGO were dectected in the order of Pt-Ru > Pt-Ni > Pt. low reduction temperatures of surface CGO indicates the low activation energy for oxygen ion conduction to metal. Oxygen ion conduction is known as de-coking mechanism of ionic conducting supports such as CGO. In activity test, fuel conversion was in the same order of Pt-Ru > Pt-Ni > Pt. Especially, 100% of fuel conversion was obtained over Pt-Ru catalysts at $500^{\circ}C$.

• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.211-218
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• 2002

In this study, Pt/Pd (1.1), PtPd (2:1) and PtPd (3:1) binary catalysts and Pt/Ru/Pd (5:4:1) ternary catalyst were designed. The catalysts were synthesized by impregnation method using $NaBH_4$ as a reducing agent. A good catalyst for methanol oxidation requires low on-set potential, stable durability and low activation energy. In order to investigate the catalytic activity for the methanol oxidation, electrochemical measurements such as cyclic voltammetry and chronoamperometry were peformed in sulfuric acid with/without methanol solution. In order to calculate the activation energy of the reaction, electrochemical measurements were also tested at different temperatures. For investigation of the structural analysis such as particle size and alloying, X-ray diffraction and transmission electron microscopy analysis were used. In order to identify the role of the Pd and to determine the composition of the surface of the Pt/Pd nanoparticles, X-ray photoelectron spectroscopy (XPS) analysis was investigated. The XPS spectra of Pd showed that Pd appears only as a metallic state in the binary catalysts. The chemical states of Pt in PtPd catalysts are both metallic and oxidative. Polarization curves and power density data were obtained by testing the DMFC unit cell performance of PtPd and PtRuPd catalysts. These data showed that Pt/Pd (2:1) and Pt/Ru/Pd (5:4:1) have better performance than Pt and Pt/Ru, respectively.

• Particle and aerosol research
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• v.8 no.2
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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.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.561-566
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• 2012

PtRuW/C catalysts were prepared with the different molar ratios of Pt : Ru : W and their compositions were analyzed by energy dispersive X-ray (EDX). The uniform distribution of particles was observed using transmission electron microscopy (TEM). An average crystalline size of 3.5~5.5 nm was calculated based on x-ray diffraction (XRD) data. The electrochemical properties such as electrochemically active surface areas, current densities, specific activities and poisoning rates, were analyzed via CO stripping, linear sweep voltammetry and chronoamperometry. From the analysis, we observed that ternary alloy catalysts, except $PtRu_2W_2/C$, have higher current densities, specific activities and stabilities than those of commercial binary catalysts. Among all in-house catalysts, Pt5Ru4W/C showed the highest specific activity of $121.05mA{\cdot}m^{-2}$ and the lowest poisoning rate of $0.01%{\cdot}s^{-1}$.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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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 $10\%$.

• Analytical Science and Technology
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• v.19 no.5
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• pp.422-432
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• 2006

The volatile organic compounds(VOCs) have been recognized as a major contributor to air pollution. The catalytic oxidation is one of the most important processes for VOCs destruction due to getting high efficiency at low temperature. In this study, monometallic Pt and bimetallic Pt-Ru, Pt-Ir were supported to ${\gamma}-Al_2O_3$. Xylene, toluene and MEK were used as reactants. The monometallic or bimetallic catalysts were prepared by the excess wetness impregnation method and were characterized by XRD, XPS, TEM and BET analysis. As a result, Pt-Ru, Pt-Ir bimetallic catalysts showed higher conversion than Pt monometallic catalyst. Pt-Ir bimetallic catalyst showed the highest conversion on the ${\gamma}-Al_2O_3$ support. In the VOCs oxidation, Pt-Ru, Pt-Ir bimetallic catalyst had multipoint active sites, so it improved the range of Pt metal state. Therefore, bimetallic catalysts showed higher conversion of VOCs than monometallic ones. In this study, the use of small amount of Ru, Ir to Pt promoted oxidation conversion of VOCs.

• Korean Journal of Materials Research
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• v.21 no.8
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• pp.419-424
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• 2011

Pt nanoparticle catalysts incorporated on $RuO_2$ nanowire support were successfully synthesized and their electrochemical properties, such as methanol electro-oxidation and electrochemically active surface (EAS) area, were demonstrated for direct methanol fuel cells (DMFCs). After fabricating $RuO_2$ nanowire support via an electrospinning method, two different types of incorporated Pt nanoparticle electrocatalysts were prepared using a precipitation method via the reaction with $NaBH_4$ as a reducing agent. One electrocatalyst was 20 wt% Pt/$RuO_2$, and the other was 40 wt% Pt/$RuO_2$. The structural and electrochemical properties of the Pt nanoparticle electrocatalysts incorporated on electrospun $RuO_2$ nanowire support were investigated using a bright field transmission electron microscopy (bright field TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. The bright field TEM, XRD, and XPS results indicate that Pt nanoparticle electrocatalysts with sizes of approximately 2-4 nm were well incorporated on the electrospun $RuO_2$ nanowire support with a diameter of approximately 50 nm. The cyclic voltammetry results showed that the Pt nanoparticle catalysts incorporated on the electrospun $RuO_2$ nanowire support give superior catalytic activity in the methanol electro-oxidation and a higher electrochemically active surface (EAS) area when compared with the electrospun Pt nanowire electrocatalysts without the $RuO_2$ nanowire support. Therefore, the Pt nanoparticle catalysts incorporated on the electrospun $RuO_2$ nanowire support could be a promising electrode for direct methanol fuel cells (DMFCs).

• Journal of the Korean Electrochemical Society
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• v.6 no.1
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• pp.13-17
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• 2003

Cryogel and aerogel Pt-Ru/C were synthesized by the sol-gel process for the electrooxidation of methanol. From XRD analysis, it was found that the catalysts had highly dispersed Pt-Ru alloys on carbon support although high temperature treatments have been conducted. Electrocatalytic activities of 3 type aerogel catalysts were investigated in half cell experiments by cyclic voltammetry. Among them, Phloroglucinol-Formaldehyde(PF) type catalyst shows the highest activity. From the results of deactivation test for each catalysts, the aerogel catalysts are found to have excellent durability compared with those prepared by colloidal method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.94.1-94.1
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• 2011

In this work, ordered mesoporous carbons (OMCs) were prepared by the conventional templating method using mesoporous silica (SBA-15) for Pt-Ru catalyst supports in fuel cells. The influence of surface modification on carbon supports on the electrochemical activities of Pt-Ru/OMCs was investigated with different pH. The neutral-treated OMCs (N-OMCs), base-treated OMCs (B-OMCs), and acid-treated OMCs (A-OMCs) were prepared by treating OMCs with 2 M $C_6H_6$, 2 M KOH, and 2 M $H_3PO_4$, respectively. The surface characteristic of the carbon supports were determined X-ray photoelectron spectroscopy (XPS). The electrochemical activities of the Pt-Ru catalysts had been enhanced when the OMCs supports were treated by basic or neutral agents, while the electrochemical activities had been decayed for the A-OMCs supported Pt-Ru.