Electrocatalytic Activity of Ordered Intermetallic Phases for Fuel Cell Applications

Casado-Rivera, Emerilis; Volpe, David J.; Alden, Laif R.; Lind, Cora; Downie, Craig; Vázquez-Alvarez, Terannie; Angelo, Antonio; DiSalvo, Francis J.; Abruña, Héctor D.

doi:10.1021/ja038497a

Cited by 504 publications

(419 citation statements)

References 25 publications

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“…An electrode coated with a film of the Re MBH possessing a binuclear Ni-Fe active site represents a previously undescribed H 2 oxidation electrocatalyst that is completely tolerant to CO; thus, even Synthesis Gas (an industrial H 2 ͞CO mixture) would provide a viable H 2 fuel source. Intriguingly, modifications to platinum surfaces that confer increased resistance to CO poisoning often depend on introduction of a second metal, as in the intermetallic materials PtBi, PtIn, or PtPb (24) or the binary alloys PtRu or PtMo (25).…”

Section: Resultsmentioning

confidence: 99%

Electrocatalytic hydrogen oxidation by an enzyme at high carbon monoxide or oxygen levels

Vincent

Cracknell

Lenz

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

249

282

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Use of hydrogen in fuel cells requires catalysts that are tolerant to oxygen and are able to function in the presence of poisons such as carbon monoxide. Hydrogen-cycling catalysts are widespread in the bacterial world in the form of hydrogenases, enzymes with unusual active sites composed of iron, or nickel and iron, that are buried within the protein. We have established that the membrane-bound hydrogenase from the ␤-proteobacterium Ralstonia eutropha H16, when adsorbed at a graphite electrode, exhibits rapid electrocatalytic oxidation of hydrogen that is completely unaffected by carbon monoxide [at 0.9 bar (1 bar ‫؍‬ 100 kPa), a 9-fold excess] and is inhibited only partially by oxygen. The practical significance of this discovery is illustrated with a simple fuel cell device, thus demonstrating the feasibility of future hydrogen-cycle technologies based on biological or biologically inspired electrocatalysts having high selectivity for hydrogen.biohydrogen ͉ electron transfer ͉ energy ͉ fuel cell ͉ hydrogenase H ydrogenases prevail throughout the microbial world and are essential to hydrogen metabolism (1). X-ray crystallography in conjunction with Fourier transform infrared spectroscopy has revealed that the active site structure of the [NiFe] hydrogenases from Desulfovibrio gigas (Dg) (2) and D. vulgaris Miyazaki F (3, 4) is a bimetallic site having Ni and Fe centers linked by bridging cysteinyl S, with the Fe additionally coordinated by one CO and two CN Ϫ ligands. Crystallographic experiments on the enzyme from D. fructosovorans involving infusion of Xe have revealed the likely positions of ''gas channels'' for transport of small molecules such as H 2 , O 2 , and CO to and from the active site (5).The vast majority of hydrogenase-containing microorganisms, including the Desulfovibrio species, live under anaerobic or semianaerobic conditions, and like their hosts, the hydrogenases are usually highly sensitive to O 2 (1). However, some bacteria are able to gain energy from H 2 oxidation under aerobic conditions. A well studied example is Ralstonia eutropha (Re, formerly Alcaligenes eutrophus) strain H16 a ␤-proteobacterium that hosts three physiologically distinct [NiFe] hydrogenases (6-8). One of these enzymes, the membrane-bound hydrogenase (MBH), is coupled via a b-type cytochrome to the respiratory chain. Sequence similarity shows that this enzyme belongs to the family of [NiFe] hydrogenases having a large subunit containing the NiOFe catalytic center and a small electron-transferring subunit accommodating three iron-sulfur clusters (9). The MBH enables Re to grow on H 2 as the sole energy source even under ambient levels of O 2 . The exceptional tolerance of Re MBH to O 2 (10) inspired us to assess its electrocatalytic activity under extremely demanding conditions, including the presence of CO, which is the classic inhibitor of hydrogen-cycling catalysts (11). This inhibition is rationalized on the basis that activation of H 2 by transition metals requires it to form a bond that involves back donation ...

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Section: Resultsmentioning

confidence: 99%

Electrocatalytic hydrogen oxidation by an enzyme at high carbon monoxide or oxygen levels

Vincent

Cracknell

Lenz

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

249

282

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“…Casado et al 79 and Roychowdhury et al 80 studied Pt-based ordered intermetallic compounds extensively and pointed out that these systems can provide predictable control over structural, geometric and electronic effects, while disordered structures cannot. While a disordered structure has varying local composition and atomic distribution, which may affect site activity, an ordered structure offers a consistent geometric and chemical environment, and thus the same activity.…”

Section: Effects Of Orderingmentioning

confidence: 99%

Nanostructured Pt-alloy electrocatalysts for PEM fuel cell oxygen reduction reaction

et al. 2010

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In this critical review, we present the current technological advances in proton exchange membrane (PEM) fuel cell catalysis, with a focus on strategies for developing nanostructured Pt-alloys as electrocatalysts for the oxygen reduction reaction (ORR). The achievements are reviewed and the major challenges, including high cost, insufficient activity and low stability, are addressed and discussed. The nanostructured Pt-alloy catalysts can be grouped into different clusters: (i) Pt-alloy nanoparticles, (ii) Pt-alloy nanotextures such as Pt-skins/monolayers on top of base metals, and (iii) branched or anisotropic elongated Pt or Pt-alloy nanostructures. Although some Pt-alloy catalysts with advanced nanostructures have shown remarkable activity levels, the dissolution of metals, including Pt and alloyed base metals, in a fuel cell operating environment could cause catalyst degradation, and still remains an issue. Another concern may be low retention of the nanostructure of the active catalyst during fuel cell operation. To facilitate further efforts in new catalyst development, several research directions are also proposed in this paper (130 references).

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“…Hence, because of their expected specific catalytic activities and selectivities, intermetallic (nano)particles synthesized by different techniques [16][17][18][19] are gaining in importance. For example, Abruna and co-workers [20,21] have prepared Pt/Pb intermetallic phases by heating metals to ca. 1000 C under vacuum in a sealed quartz tube and used them as catalyst for fuel cells.…”

Section: Introductionmentioning

confidence: 99%

Phase diagrams of microemulsions containing reducing agents and metal salts as bases for the synthesis of metallic nanoparticles

Najjar

2009

Journal of Colloid and Interface Science

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We studied the phase diagrams of microemulsions with a view to using these systems for the synthesis of metallic Pt, Pb, and Bi nanoparticles as well as of intermetallic Pt/Pb and Pt/Bi nanoparticles. The microemulsions consisted of H 2 O/salt -n-decane -SDS -1-butanol. The salt was either one metal precursor (H 2 PtCl 6 ·6H 2 O, Pb(NO 3 ) 2 , or Bi(NO 3 ) 3 ·5H 2 O), a mixture of two metal precursors (H 2 PtCl 6 ·6H 2 O + Pb(NO 3 ) 2 or H 2 PtCl 6 ·6H 2 O + Bi(NO 3 ) 3 ·5H 2 O), or the reducing agent (NaBH 4 ). In addition, other salts needed to be added in order to solubilize the metal precursors, to stabilize the reducing agent, and to adjust the ionic strength. Combining the microemulsion (µe1) that contains the metal precursor(s) with the microemulsion (µe2) that contains the reducing agent leads to metallic nanoparticles. To study systematically how the shape and size of the synthesized metallic nanoparticles depend on the size and shape of the respective microemulsion droplets, first of all one has to find those conditions under which µe1 and µe2 have the same structure. For that purpose we determined the water emulsification failure boundary (wefb) of each microemulsion as it is at the wefb where the water droplets are known to be spherical. We found that the ionic strength (I) of the aqueous phase as well as the hard acid and hard base properties of the ions are the key tuning parameters for the location of the wefb.

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Electrocatalytic Activity of Ordered Intermetallic Phases for Fuel Cell Applications

Cited by 504 publications

References 25 publications

Electrocatalytic hydrogen oxidation by an enzyme at high carbon monoxide or oxygen levels

Electrocatalytic hydrogen oxidation by an enzyme at high carbon monoxide or oxygen levels

Nanostructured Pt-alloy electrocatalysts for PEM fuel cell oxygen reduction reaction

Phase diagrams of microemulsions containing reducing agents and metal salts as bases for the synthesis of metallic nanoparticles

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