Characterization of direct methanol fuel cell components by electron microscopy and X-ray microchemical analysis

Aricò, A.S.; Cretı̀, P.; Poltarzewski, Z.; Mantegna, R.; Kim, H.; Giordano, N.

doi:10.1016/s0254-0584(97)80061-2

Cited by 32 publications

(38 citation statements)

References 10 publications

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“…The lattice parameter estimated from XRD data for the Pt-Ru/C catalysts is smaller than for Pt, in agreement with the expected contraction of the lattice due to the partial substitution of Pt by Ru in the fcc structure. 28 The fraction of alloyed Ru in the Pt-Ru/C electrocatalysts was estimated assuming that the variation of lattice parameter on Ru content follows Vegard's law…”

Section: Resultsmentioning

confidence: 99%

Influence of Particle Size on the Properties of Pt–Ru∕C Catalysts Prepared by a Microemulsion Method

Godoi

Perez

Villullas

2007

J. Electrochem. Soc.

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Pt-Ru/C nanocatalysts were prepared by a microemulsion method using different values of water/surfactant molar ratio in order to get different particle sizes. Crystallite sizes and structural properties were determined by X-ray diffraction. Particle size and distribution were characterized by transmission electron microscopy and average composition was determined by energydispersive X-ray analysis. Thermogravimetric analysis was used to estimate the amount of supported metals. Differential scanning calorimetry measurements indicated the presence of hydrous ruthenium oxides in the as-prepared catalysts. Results for the oxidation of adsorbed CO as well as for methanol oxidation revealed significant differences in the behavior of the prepared catalysts. All together, the results demonstrate that the variation of particle size produces changes in other properties of the Pt-Ru/C catalysts and that to establish direct correlations between electrocatalytic activity and particle size is not possible because the effects of the different parameters cannot be separated.

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Section: Resultsmentioning

confidence: 99%

Influence of Particle Size on the Properties of Pt–Ru∕C Catalysts Prepared by a Microemulsion Method

Godoi

Perez

Villullas

2007

J. Electrochem. Soc.

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“…40,41,[46][47][48] Arc melted Pt-Ru alloys show a = 0.3904 nm for Pt-Ru 80:20 and 0.3864 nm for Pt-Ru 50:50, while this last composition has a value of 0.38965 nm when prepared by chemical reduction with sodium borohydride on a carbon support. 47 Radmilovic et al 40 found 0.3898 nm for the 75:25 and 0.3884 nm for the 50:50 PtRu/C alloys.…”

Section: Cell Parameter "A"mentioning

confidence: 95%

“…The values of a for materials prepared with the FAM are larger when compared with those of the catalysts obtained by other methods. 40,41,[46][47][48] Arc melted Pt-Ru alloys show a = 0.3904 nm for Pt-Ru 80:20 and 0.3864 nm for Pt-Ru 50:50, while this last composition has a value of 0.38965 nm when prepared by chemical reduction with sodium borohydride on a carbon support.47 Radmilovic et al 40 found 0.3898 nm for the 75:25 and 0.3884 nm for the 50:50 PtRu/C alloys. Thus, this method seems to favor the formation of solid solutions more than the FAM.…”

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confidence: 99%

Carbon monoxide oxidation on Pt-Ru electrocatalysts supported on high surface area carbon

Colmati¹,

Lizcano-Valbuena²,

Câmara³

et al. 2002

J. Braz. Chem. Soc.

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Este trabalho descreve a preparação e caracterização de ligas dispersas de Pt-Ru sobre carbono de alta área superficial, as quais foram avaliadas para a oxidação de CO em eletrodos de disco rotatório/camada fina porosa e para a oxidação de hidrogênio em células a combustível de eletrólito polimérico alimentadas com hidrogênio contendo 100 ppm de CO. Tratamentos térmicos (H 2 , 300 °C) aplicados aos catalisadores melhoram a tolerância a pequenas quantidades de CO e, em alguns casos, reduzem o potencial necessário para promover a oxidação de CO durante a varredura do potencial. Sob condições operacionais em uma célula a combustível na presença de CO, foi observado que os melhores resultados foram obtidos quando a liga Pt-Ru/C foi preparada por redução simultânea dos íons Pt (IV) e Ru (III), diferentemente da redução seqüencial.This work describes the preparation and characterization of Pt-Ru alloys dispersed on high surface area carbon, which were evaluated for CO oxidation on thin porous coating rotating disk electrodes and for hydrogen oxidation on polymer electrolyte fuel cells fed with hydrogen containing 100 ppm CO. A thermal treatment (H 2 , 300 o C) applied to the catalysts improves the tolerance to small quantities of CO and, in some cases, reduces the potential necessary to promote the CO oxidation during a linear potential scan. Under operational conditions in a fuel cell in the presence of CO it was observed that the best results were obtained when the Pt-Ru/C alloy was prepared by simultaneous reduction of the ions Pt (IV) and Ru (III), as opposed to a sequential reduction.Keywords: carbon monoxide, Pt-Ru alloys, supported catalysts, thermal treatment IntroductionIn recent years there has been a steadily growing concern with the degradation of the environment and the effect of pollutants on human health.1 High levels of pollutants are produced by internal combustion engines, particularly those running on diesel, in large urban centers. Today, the use of clean energy sources is considered an urgent necessity and, among the alternatives, fuel cells are attracting much interest.2 In particular, polymer electrolyte membrane fuel cells (PEMFC), are considered good candidates for transportation and portable applications because they are capable of delivering high power densities and can start operating at room temperature.In spite of the efforts to develop the direct methanol fuel cell (DMFC), which has the advantage of using a liquid fuel, the most efficient low temperature fuel cells still use hydrogen as fuel. The cheapest way of producing hydrogen is by reforming fossil fuels or low molecular weight alcohols.3 This process produces 6-7% CO, which can be reduced to 1-2% by a shift reaction and to levels smaller than 100 ppm by partial oxidation. 4 This CO adsorbs strongly on the Pt catalyst of the fuel cell electrode inhibiting the anodic reaction. The DMFC is not free of this problem, because the oxidation of methanol on Pt produces CO as an intermediate. 5 The possibility of using PEMFC in transportatio...

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“…The observation has been attributed to the increase of the coverage of Pt-Ru surfaces by oxy-species due to Ru. 3,[33][34][35] However, no crystalline Pt-oxide phase in our catalyst is detected from XRD, possibly indicating that Pt oxides are present mostly at the surface in an amorphous phase. Figure 7 shows the Ru 3p 3/2 peak for the Pt1R1 sample.…”

Section: Resultsmentioning

confidence: 84%

Mixed Phase Pt-Ru Catalyst for Direct Methanol Fuel Cell Anode by Flame Aerosol Synthesis

Chakraborty

Bischoff

Chorkendorff

et al. 2005

J. Electrochem. Soc.

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A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst was found to be a mixture of nanocrystalline, mostly unalloyed Pt and an amorphous phase mostly of Ru and to a lesser extent of Pt oxides on top of the crystalline phase. The flame-produced Pt1Ru1 demonstrated similar onset potential but ∼60% higher activity compared to commercially available Pt1Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy.

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Characterization of direct methanol fuel cell components by electron microscopy and X-ray microchemical analysis

Cited by 32 publications

References 10 publications

Influence of Particle Size on the Properties of Pt–Ru∕C Catalysts Prepared by a Microemulsion Method

Influence of Particle Size on the Properties of Pt–Ru∕C Catalysts Prepared by a Microemulsion Method

Carbon monoxide oxidation on Pt-Ru electrocatalysts supported on high surface area carbon

Mixed Phase Pt-Ru Catalyst for Direct Methanol Fuel Cell Anode by Flame Aerosol Synthesis

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