• Journal of Energy Engineering
• /
• v.7 no.1
• /
• pp.35-43
• /
• 1998

Electrodes using for the anode electrode of direct methanol fuel cell with Pt/C and Pt/Ru/C catalyst were prepared and characterized by SEM, TEM, thermal analysis and electrochemical analysis. The half cell tests were carried out with 1 M $H_2SO_4$ electrolyte and 1 M $CH_3OH$ in order to evaluate the electrode performance. The employed electrochemical methods were cyclic vol-tammetry and potentiodynamic polarization experiments. It was found that 20 w% polytetrafluoroethylene (PTFE) content in catalyst showed the best performance due to the best platinum utilization on PTFE-containing catalyst layer. It was found that Pt/Ru/C binary catalyst inhibited the poisoning of anode electrode showing improved performance compared to the Pt/C catalyst by the adsorption of oxygen containing species on the electrode surface at same time. The apparent activation energy for methanol oxidation on the Pt/Ru/C and Pt/C catalyst layer was 11.60 kJ/mol and 26.85 kJ/mol, respectively.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.1
• /
• pp.151-156
• /
• 2010

In this paper, we characterized bimetallic Pt-Ru/C alloy catalysts having four different compositions and compared the catalytic activities of the prepared alloys for CO oxidation. ICP-AES, EDS, XRD, TEM, and XAS were used to investigate the composition, degree of alloying, particle size, and electronic structure of the prepared Pt-Ru/C catalysts. Those results indicated the synthesis of the alloy catalysts with intended composition and uniform size. The electrochemical study of the characterized alloys showed higher catalytic activity for CO oxidation than that of the commercial Pt/C (E-TEK, Inc., 20 wt %) catalyst. Especially, it was shown that the alloy catalyst with Ru composition of 50 atomic % gave the highest catalytic activity for CO oxidation.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.86.2-86.2
• /
• 2011

저온형 연료전지인 직접 메탄올 연료전지(Direct Methanol Fuel Cells, DMFC)는 친환경적인 발전 시스템, 높은 에너지 효율의 장점 때문에 주목을 받고 있으나 연료극의 촉매로 사용되는 금속은 고가의 귀금속인 Pt와 Ru가 요구되어 제조비용이 비싸기 때문에 촉매의 양을 줄이고, 반응 도중 생성되는 CO에 의한 촉매의 피독 문제 등 해결하여야 할 점이 산적해 있어 연료전지 중 촉매의 활성을 높이는 연구들이 활발히 이루어지고 있다. 종래의 MEA의 촉매층 제조공정은 우선 환원석출법에 의해 Pt-Ru/C를 합성하고 Nafion 용액에 혼합하여 Pt-Ru/C 슬러리를 제조한다. 이 방법에서는 carbon sheet에 spray 방법으로 Pt-Ru/C 촉매층이 만들어지기 때문에, Pt-Ru 촉매가 Nafion에 의해 부분적으로 매몰되어 촉매의 전기화학적 활성이 떨어지는 문제점이 있다. 이를 해결하는 방안으로 펄스전류를 이용하여 Pt-Ru 합금입자를 carbon sheet에 전기화학적으로 담지 시켜 Nafion에 매몰되는 것을 방지하는 펄스전해법 연구가 진행되고 있다. 그러나 촉매의 입자크기가 일반적으로 50~70 nm 이상으 크기 때문에 촉매의 낮은 활성이 문제점으로 야기되고 있다. 본 연구에서는 Pt-Ru/C 촉매층 제조 문제점을 해결하고, 촉매의 전기화학적 활성을 증가시키기 위해서 2~4 nm Pt-Ru 콜로이드를 전해액으로 사용하고, 전기영동법을 이용하여 Pt-Ru 나노 입자를 carbon sheet($1{\times}1cm^2$) 에 담지 시켰다. 전기영동법에서 균일한 Pt-Ru 촉매층의 제조를 위해 전류인가 방법으로는 펄스전류를 사용하였고, 실험변수로는 전해액 pH, duty cycle, 담지시간을 선정하였다. 합성된 Pt-Ru 콜로이드를 TEM분석으로 나노입자의 크기와 분산성 분석하였고, 콜로이드 나노입자의 표면전하 상태를 분석하기 위해 zeta-potential을 분석하였다. Pt-Ru/C의 촉매의 전기화학적 활성을 분석하기 위하여 0.5 M H_2SO_4$ 와 1 M $CH_3OH$ 혼합용액에 CV(Cyclic Voltammetry)실시하였고, carbon sheet 전극 상 Pt-Ru의 분산성 확인을 위하여 FE-SEM분석을 수행하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.188-190
• /
• 2007

The MEA with the catalyst layer containing PtRu black and 60 wt. %Pt/C as their anode and cathode catalysts. For find to effect of carbon support, the MEA with platinum black for cathode catalyst was fabricated. The performance of the MEA with the catalyst layer containing (PtRu black:60 wt.% Pt/C) as their anode and cathode catalyst has shown competitively higher value than the performance of the MEA with the catalyst layer containing (PtRu black:Pt black) as their anode and cathode catalyst.

• Clean Technology
• /
• v.18 no.4
• /
• pp.432-439
• /
• 2012

The electrocatalytic oxidation of CO was studied using carbon-supported 20 wt% PtRu (PtRu/C) catalysts, which were prepared with different Pt : Ru atomic ratios from 7 : 3 to 3 : 7 using a colloidal method combined with a freeze-drying procedure. The bimetallic PtRu/C catalysts were characterized by various physicochemical analyses, including X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). CO stripping voltammetry measurements indicated that the addition of Ru with a Pt catalyst significantly improved the electrocatalytic activity for CO electrooxidation. Among the tested catalysts, the $Pt_5Ru_5/C$ catalyst had the lowest onset potential (vs.Ag/AgCl) and the largest CO EAS. Structural modification via lattice parameter change and electronic modification in the unfilled d band states for Pt atoms may facilitate the electrooxidation of CO.

• Carbon letters
• /
• v.11 no.4
• /
• pp.336-342
• /
• 2010

Different oxidation treatments on CNTs using diluted 4.0 M $H_2SO_4$ solution at room temperature and or at $90^{\circ}C$ reflux conditions were investigated to elucidate the physical and chemical changes occurring on the treated CNTs, which might have significant effects on their performance as catalyst supports in PEM fuel cells. Raman spectroscopy, X-ray diffraction and transmission electron microscope analyses were made for the acid treated CNTs to determine the particle size and distribution of the CNT-supported Pt-Ru nanoparticles. These CNT-supported Pt-based nanoparticles were then employed as anode catalysts in PEMFC to investigate their catalytic activity and single-cell performance towards $H_2$ oxidation. Based on PEMFC performance results, refluxed Pt-Ru/CNT catalysts prepared using CNTs treated at $90^{\circ}C$ for 0.5 h as anode have shown better catalytic activity and PEMFC polarization performance than those of the commercially available Pt-Ru/C catalyst from ETEK and other Pt-Ru/CNT catalysts developed using raw CNT, thus demonstrating the importance of acid treatment in improving and optimizing the surface properties of catalyst support.

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

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.286-290
• /
• 2008

Small amounts of CO in reformate fuel gas effectively block platinum catalysts by strong adsorption on the platinum surface at the operation temperature of $60{\sim}80^{\circ}C$ in PEMFC. To oxidate CO, Ru/C layer (CO filter) was placed between Pt/C layer and GDL (gas diffusion layer) in this study. Ru/C filter provided good CO-tolerant PEMFC anode, but decreased the performance of unit cell about 10% at 0.6 V due to mass transfer resistance from Ru/C filter thickness and increase of charge transfer resistance. Membrane degradation is one of the most important factors limiting the life-time of PEMFCs. Membrane durability would be dependent on the electrode catalyst type. It seemed that Ru catalyst layer would shorten the life time of PEMFC as enhanced the fluoride emission rate of membrane in acceleration test.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.97.2-97.2
• /
• 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 $500^{\circ}C$.

• Applied Chemistry for Engineering
• /
• v.23 no.6
• /
• pp.561-566
• /
• 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 $0.01%{\cdot}s^{-1}$.