Surface segregation of a Pt–Au alloy: An atom-probe field ion microscope investigation

Tsong, Tien T.; Ng, Yee S.; McLane, S. B.

doi:10.1063/1.440208

Cited by 78 publications

(32 citation statements)

References 25 publications

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“…For the Ag-Au (62,69) and Pd-Au (68) alloys a number of experimental studies indicate that no surface segregation occurs, in contradiction with other experimental data for Ag-Au alloys (57,75,76,83,84), PdAu alloys (79), and Pt-Au alloys (81,85) as well as most theoretical models. This absence of segregation may be due to a lack of thermodynamic equilibrium (69) or substantial preferential sputtering of Au atoms from the surface (68).…”

Section: Predicting and Observing Segregationmentioning

confidence: 61%

Surface segregation from gold alloys

1987

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Among the properties of alloys affected by surface segregation are corrosion resistance and strength. In this paper, the surface segregation phenomenon is reviewed, with particular attention given to gold-containing alloys. A brief discussion of the various thermodynamic models for surface segregation is provided. The results of experimental investigations of surface segregation for gold-containing alloys are summarized and explained in terms of some of the thermodynamic models.

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Section: Predicting and Observing Segregationmentioning

confidence: 61%

Surface segregation from gold alloys

1987

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“…Among the Pd 3 X alloys with strong segregation energies, only Pd 3 W is known to have a stable phase at this 3:1 composition, 43,44 as also observed for Pt 3 Co and Pt 3 Ni alloys. We expect that such systems with a stable ordered phase at 3:1 ratio are more likely to be ordered.…”

Section: Resultsmentioning

confidence: 86%

Improved Non-Pt Alloys for the Oxygen Reduction Reaction at Fuel Cell Cathodes Predicted from Quantum Mechanics

Sha

Merinov

et al. 2010

J. Phys. Chem. C

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“…22 The present results are in good agreement with the experimental work of Tsong et al, who investigated surface segregation trends in Pt-Au alloys by applying atom-probe field ion microscopy. 23 Hörn-ström et al also reported a strong surface segregation of gold in three different Pt-Au alloys containing between 2 and 90 wt % gold. The alloys were studied using Auger electron spectroscopy.…”

Section: Resultsmentioning

confidence: 94%

Alternative Catalyst Supports Deposited on Nanostructured Thin Films for Proton Exchange Membrane Fuel Cells

Garsuch

Stevens

Sanderson

et al. 2010

J. Electrochem. Soc.

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A series of platinum-coated underlayer materials, alumina, gold, titanium carbide, and titanium disilicide, deposited by a high throughput magnetron sputtering method have been investigated as cathode catalyst supports in fuel cells. Orthogonal thickness gradients of the underlayer materials ͑0-100 nm planar equivalent͒ and the platinum top layer ͑0-75 nm planar equivalent͒ made up the 76 ϫ 76 mm libraries. The resulting catalyst films were characterized by surface profilometry, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical properties of the catalyst composition spreads were investigated simultaneously in 64-electrode proton exchange membrane fuel cells with emphasis placed on the determination of the electrochemical surface area ͑ECSA͒ as a function of underlayer thickness and chemistry. The present study shows that gold and titanium disilicide used as underlayers on 3M's nanostructured thin film supports lead to a loss of ECSA during operation. Migration and surface accumulation were observed when gold was used as underlayer material. For titanium disilicide, alloying and the generation of platinum silicide phases occurred. Alumina and titanium carbide were found to be potentially acceptable underlayer materials as well as alternative support materials on the basis of their influence on the catalyst surface area.Polymer electrolyte membrane fuel cells ͑PEMFCs͒ are promising power sources for automotive applications in the future. 1 The main environmental advantage of using PEMFCs in vehicles is the reduction of carbon dioxide emissions, pollutants, and consumption of fossil fuels. 2 To fully commercialize PEMFCs for automotive vehicles, their high production cost needs to be reduced while improving performance and durability. The core of a PEMFC, the membrane electrode assembly ͑MEA͒, consists of two electrocatalyst electrodes ͑anode and cathode͒ with gas diffusion layers ͑GDLs͒ on either side of the proton-conducting ion-exchange membrane. Each of these MEA components contributes to the overall performance, stability durability, robustness, and cost of a PEMFC, and thus research efforts have been focused on the improvement of the electrocatalyst and membrane properties. 3 Platinum or platinum alloys are commonly used as the catalyst on the anode side for the hydrogen oxidation reaction ͑HOR͒ and on the cathode side for the oxygen reduction reaction ͑ORR͒ in a PEMFC. These catalysts may consist of highly dispersed platinum particles ͑2-3 nm͒ supported on carbon blacks, activated carbon, or carbon nanotubes. A range of factors 4 are known to contribute to the significant performance degradation of PEMFCs that can occur during long-term operation or as a result of adverse operating conditions ͑e.g., fuel starvation on the anode side during start-up and shutdown 5 ͒. These include Pt-catalyzed corrosion of the carbon support, 6 oxidation and decomposition of the GDL, 7 dissolution or poisoning of the Pt catalysts on the cathode and anode side, 8 and degr...

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Surface segregation of a Pt–Au alloy: An atom-probe field ion microscope investigation

Cited by 78 publications

References 25 publications

Surface segregation from gold alloys

Surface segregation from gold alloys

Improved Non-Pt Alloys for the Oxygen Reduction Reaction at Fuel Cell Cathodes Predicted from Quantum Mechanics

Alternative Catalyst Supports Deposited on Nanostructured Thin Films for Proton Exchange Membrane Fuel Cells

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