CO tolerance of ordered intermetallic phases

de‐los‐Santos‐Álvarez, Noemí; Alden, Laif R.; Rus, Eric D.; Wang, H.; DiSalvo, Francis J.; Abruña, Héctor D.

doi:10.1016/j.jelechem.2008.10.028

Cited by 57 publications

(43 citation statements)

References 40 publications

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“…[5]. Furthermore, they have shown that the current densities of PtPb and PtBi electrodes are superior to those of a pure platinum catalyst [6][7][8] and that those intermetallics are almost immune against CO and S poisoning [9,10]. Thus, PtPb and PtBi intermetallic phases are promising materials to replace monometallic platinum nanoparticles in fuel cells.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

et al. 2014

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Water-in-oil (w/o) microemulsions were used as a template for the synthesis of mono-and bi-metallic nanoparticles. For that purpose, w/o-microemulsions containing H 2 PtCl 6 , H 2 PtCl 6 + Pb(NO 3 ) 2 and H 2 PtCl 6 + Bi(NO) 3 , respectively, were mixed with a w/o-microemulsion containing the reducing agent, NaBH 4 . The results revealed that it is possible to synthesize Pt, PtPb and PtBi nanoparticles of ~3-8 nm in diameter at temperatures of about 30°C. The catalytic properties of the bimetallic PtBi and PtPb nanoparticles were studied and compared with monometallic platinum nanoparticles. Firstly, the electrochemical oxidation of formic acid to carbon monoxide was investigated, and it was found that the resistance of the PtBi and PtPb nanoparticles against the catalyst-poisoning carbon monoxide was significantly higher compared to the Pt nanoparticles. Secondly, investigating the reduction of 4-nitrophenol to 4-aminophenol,we found that the bimetallic NPs are most active at 23 °C, while the order of the activity changes at higher temperatures, i.e., that the Pt nanoparticles are the most active ones at 36 and 49 °C. Furthermore, we observed a strong influence of the support, which was either a polymer or Al 2 O 3 . Thirdly, for the hydrogenation of allylbenzene to propylbenzene, the monometallic Pt NPs turned out to be the most active catalysts, followed by the PtPb and PtBi NPs. Comparing the two bimetallic nanoparticles, one sees that the PtPb NPs are significantly more active than the respective PtBi NPs. OPEN ACCESSCatalysts 2014, 4 257

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Section: Introductionmentioning

confidence: 99%

Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

et al. 2014

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“…17,18 Enhanced activity of Pt in combination with Bi for this reaction was referred to electronic effect, 19,20 improved tolerance to CO poisoning, 21 bi-functional effect 9 or to ensemble effect. 22 However, neither of the Pt-Bi catalysts is stable at moderate or higher potentials (beyond 0.4 V/AgAgCl) due to Bi dissolution.…”

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confidence: 99%

Formic Acid Oxidation at Platinum-Bismuth Clusters

Lović¹,

Stevanović²,

Tripković³

et al. 2014

J. Electrochem. Soc.

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Formic acid oxidation was studied on platinum-bismuth deposits on glassy carbon (GC) substrate. The catalysts of equimolar ratio were prepared by potentiostatic deposition using chronocoulometry. Bimetallic structures obtained by two-step process, comprising deposition of Bi followed by deposition of Pt, were characterized by AFM spectroscopy which indicated that Pt crystallizes preferentially onto previously formed Bi particles. The issue of Bi leaching (dissolution) from PtBi catalysts, and their catalytic effect alongside the HCOOH oxidation is rather unresolved. In order to control Bi dissolution, deposits were subjected to electrochemical oxidation, in the relevant potential range and supporting electrolyte, prior to use as catalysts for HCOOH oxidation. Anodic striping charges indicated that along oxidation procedure most of deposited Bi was oxidized. ICP mass spectroscopy analysis of the electrolyte after this electrochemical treatment revealed that Bi was only partly dissolved indicating the possibility for formation of some Bi oxide species. Moreover, EDX analysis of the as prepared (Pt@Bi/GC) catalysts and those oxidized confirmed appreciably higher content of oxygen in the latter. Catalysts prepared in this way exhibit about 10 times higher activity for formic acid oxidation in comparison to pure Pt, as revealed both by potentiodynamic and quasy-potentiostatic measurements. This high activity is the result of well-balanced ensemble effect induced by Bi-oxide species interrupting Pt domains. Prolonged cycling and chronoamperometry tests disclosed exceptional stability of the catalyst during formic acid oxidation. The activity is compatible with the activity of previously studied Pt 2 Bi alloy but the stability is significantly better.

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“…Among the several intermetallic phases (PtPb, PtBi, Pt 3 Ti, Pt 3 Zr, Pt 3 Ta and Pt 2 Ta) PtPb and Pt 2 Ta exhibited CO stripping potentials less positive than bulk Pt whereas PtBi exhibited virtual immunity to CO poisoning, i.e., CO probably does not adsorb [84]. Globally, the other intermetallic phases exhibited little or no improvement over Pt.…”

Section: Co Oxidation On Pt-pbmentioning

confidence: 99%

Catalysts for Methanol Oxidation

González

Mota-Lima

2013

Direct Alcohol Fuel Cells

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Methanol electroxidation proceeds via a multistep reaction. Herein, mechanisms of reaction and reaction rates of sub-set of the mechanism on different surfaces are discussed. Platinum is a reasonable catalyst for the first methanol electroxidation steps (dehydrogenation), but not for the last (CO electroxidation). Hence, alloying Platinum with a second metal was used as a strategy to enhance the rate of the last step. Accordingly, enhanced rates of CO electroxidation are attained by modifying the bonding energy of the adsorbate to the catalyst or by promoting the formation of oxygenated species at lower overvoltage. Finally, new perspectives on the field of methanol catalysts are commented including the search for catalysts that promote early onset of oscillations, i.e. under lower overvoltage. IntroductionMethanol is the typical fuel with one carbon (C1) atom for fuel cells. Methanol was one of the first small molecules chosen to study the oxidation on platinum group metals in the very early beginning of electrocatalysis. In that time, the oxidation of other C1 molecules such as formic acid and formaldehyde (interest in CO oxidation came latter with the oxidation of reformatted gases) were investigated as a model oxidation because their elementary steps were supposedly present in the mechanism of methanol oxidation. From the point of view of CO 2 emission, methanol has, among the other small molecules, the highest energy production per unit of produced

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CO tolerance of ordered intermetallic phases

Cited by 57 publications

References 40 publications

Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

Catalytic Activity of Mono- and Bi-Metallic Nanoparticles Synthesized via Microemulsions

Formic Acid Oxidation at Platinum-Bismuth Clusters

Catalysts for Methanol Oxidation

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