Nonalloyed Carbon-Supported PtRu Catalysts for PEMFC Applications

Papageorgopoulos, Dimitrios; Heer, MP de; Keijzer, M.A. de; Pieterse, J.A.Z.; Bruijn, FA Dick de

doi:10.1149/1.1690286

Cited by 29 publications

(8 citation statements)

References 35 publications

(50 reference statements)

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“…In X-ray diffraction (XRD) measurements these authors only found reflection spots for the pure Pt and Ru phases, supporting the idea that the Pt and Ru particles were not alloyed [11]. Using the same procedure for catalyst synthesis as described in [11], Papageorgopoulos et al obtained similar results [12]. They ascribed the high CO tolerance of these catalysts to a combination of the high dispersion of these catalysts, with particle sizes between 1 and 1.5 nm, and to the presence of separate Pt and Ru phases.…”

Section: Introductionmentioning

confidence: 63%

On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts

et al. 2006

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The role of atomic scale intermixing for the electrocatalytic activity of bimetallic PtRu anode catalysts in reformate operated polymer electrolyte fuel cells (PEFC) was investigated, exploiting the specific properties of colloid based catalyst synthesis for the selective preparation of alloyed and nonalloyed bimetallic catalysts. Three different carbon supported PtRu catalysts with different degrees of Pt and Ru intermixing, consisting of (i) carbon supported PtRu alloy particles (PtRu/C), (ii) Pt and Ru particles co-deposited on the same carbon support (Pt+Ru/C), and (iii) a mixture of carbon supported Pt and carbon supported Ru (Pt/C+Ru/C) as well as the respective monometallic Pt/C and Ru/C catalysts were prepared and characterized by electron microscopy (TEM), X-ray absorption spectroscopy, and CO stripping. Their performance as PEFC anode catalysts was evaluated by oxidation of a H 2 /2%CO gas mixture (simulated reformate) under fuel cell relevant conditions (elevated temperature, continuous reaction and controlled reactant transport) in a rotating disk electrode (RDE) set-up. The CO tolerance and H 2 oxidation activity of the three catalysts is comparable and distinctly different from that of the monometallic catalysts. The results indicate significant transport of the reactants, CO ad and/or OH ad , between Pt and Ru surface areas and particles for all three catalysts, with only subtle differences from the alloy catalyst to the physical mixture. The high activity and CO tolerance of the bimetallic catalysts, through the formation of bimetallic surfaces, is explained, e.g., by contact formation in nanoparticle agglomerates or by material transport and subsequent surface decoration/surface alloy formation during catalyst preparation, conditioning, and operation. The instability and mobility of the catalysts under these conditions closely resembles concepts in gas phase catalysis.

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Section: Introductionmentioning

confidence: 63%

On the Role of Reactant Transport and (Surface) Alloy Formation for the CO Tolerance of Carbon Supported PtRu Polymer Electrolyte Fuel Cell Catalysts

et al. 2006

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“…Important results in this respect were obtained at Pt single crystal model systems [12][13][14], nanoparticulate model systems [15], Pt nanoparticles, which were decorated with Ru [16,17], and non-alloy systems [18]. All these experiments with non-alloyed phaseseparate systems lead to a similar conclusion: a significant promotion effect of ruthenium was observed.…”

Section: Introductionmentioning

confidence: 73%

Binary Mixtures of Carbon Supported Pt and Ru Catalysts for PEM Fuel Cells

et al. 2006

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Commercially available carbon‐supported pure Pt and pure Ru catalysts were heat treated in order to modify their individual particle sizes, mixed in a mortar and tested for their suitability as anode catalysts in polymer electrolyte fuel cells (PEMFCs). The procedure chosen for mixing monometallic catalysts should bring more flexibility to the preparation of catalysts, which could thus be easily adjusted to the working conditions. The catalyst mixtures were structurally characterized using a combination of X‐ray diffraction (XRD) and transmission electron microscopy (TEM), and indicated an increase in particle size with heat treatment temperature, while the size distribution remained sufficiently narrow. The particle size effect on the resulting activity of the catalyst mixtures was investigated by current‐voltage measurements (U/i curves) in single cell fuel cells. A mixture of the as‐received platinum and ruthenium gave the best results, which was almost comparable to a commercial Pt‐Ru alloy catalyst purchased from E‐TEK inc. Only a minor decrease in cell performance was seen during long term operation. Following operation, the X‐ray diffraction patterns show reflections of the Pt fcc phase, but not the hcp Ru phase. This may be explained by leaching of the pure ruthenium catalysts and re‐decoration on Pt nanoparticles, or by formation of an amorphous Ru oxide or, less likely, Pt‐Ru alloy during operation. However, these structural changes do not seem to significantly affect the cell performance.

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“…One of the key components that determine the performance and cost of PEMFCs is the electrode catalyst. Pt-based catalyst is widely used as the electrocatalytic material in PEMFCs for its high activity for both electro-oxidation of hydrogen at the anode and reduction of oxygen at the cathode. , Unfortunately, Pt catalyst is susceptible to CO poisoning when using fuel gases containing even a very low amount of CO and will lose its catalytic activity with respect to time, leading to the Pt catalyst poisoning . Klaiber et al reported that the presence of CO at a volume ratio as low as 1 × 10 –6 in these fossil fuels would make the Pt catalyst poisoned and lose its catalytic activity .…”

Section: Synergetic Catalytic Effectsmentioning

confidence: 99%