Study of the Exchange Current Density for the Hydrogen Oxidation and Evolution Reactions

Neyerlin, Kenneth C.; Gu, Wenbin; Jorné, Jacob; Gasteiger, Hubert A.

doi:10.1149/1.2733987

Cited by 398 publications

(439 citation statements)

References 27 publications

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“…13b. Every catalyst was reported previously, 28,41 except for Pt 5 La, which is from the current study. There are several challenges facing the implementation of Pt alloys with early transition metals (or lanthanides) as oxygen reduction catalysts in fuel cells.…”

Section: Alloys Of Pt and Early Transition Metalsmentioning

confidence: 93%

“…Consequently, to understand the high activity of this catalyst, we employed DFT calculations. Unlike Pt, Pt 3 Ni or Pt 3 Y, Pt 5 La does not form a closely packed structure in the bulk. 199 The bulk structure is comprised of alternating layers of pure Pt and Pt and La, parallel to the (001) plane, as shown schematically in Fig.…”

Section: Alloys Of Pt and Early Transition Metalsmentioning

confidence: 97%

“…In-depth surface composition information of Pt 5 La was extracted from angle resolved XPS spectra recorded using a Theta Probe instrument from Thermo Scientific. The chamber has a base pressure of 5 Â 10 À10 mbar.…”

Section: Ultra High Vacuum Measurementsmentioning

confidence: 99%

“…† The anode loading could be dropped to 0.05 mg cm À2 without measurable kinetic losses. 5 However, 0.4 mg cm À2 is currently needed at the cathode, 6,7 where the oxygen reduction reaction (ORR) takes place:…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Understanding the electrocatalysis of oxygen reduction on platinum and its alloys

Stephens

Bondarenko

Grønbjerg

et al. 2012

Energy Environ. Sci.

1,054

1,024

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The high cost of low temperature fuel cells is to a large part dictated by the high loading of Pt required to catalyse the oxygen reduction reaction (ORR). Arguably the most viable route to decrease the Pt loading, and to hence commercialise these devices, is to improve the ORR activity of Pt by alloying it with other metals. In this perspective paper we provide an overview of the fundamentals underlying the reduction of oxygen on platinum and its alloys. We also report the ORR activity of Pt 5 La for the first time, which shows a 3.5-to 4.5-fold improvement in activity over Pt in the range 0.9 to 0.87 V, respectively. We employ angle resolved X-ray photoelectron spectroscopy and density functional theory calculations to understand the activity of Pt 5 La.

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Section: Alloys Of Pt and Early Transition Metalsmentioning

confidence: 93%

Section: Alloys Of Pt and Early Transition Metalsmentioning

confidence: 97%

Section: Ultra High Vacuum Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the electrocatalysis of oxygen reduction on platinum and its alloys

Stephens

Bondarenko

Grønbjerg

et al. 2012

Energy Environ. Sci.

1,054

1,024

View full text Add to dashboard Cite

show abstract

“…For the hydrogen oxidation reaction (HOR) at the anode, a negligible overpotential loss was achieved with pure hydrogen using 50 mg cm À 2 Pt NPs 12,13 . However, the challenge remains in employing inexpensive reformate hydrogen, wherein the p.p.m.-level of carbon monoxide (CO) impurities can severely deactivate the Pt catalysts [14][15][16] .…”

mentioning

confidence: 99%

Ordered bilayer ruthenium–platinum core-shell nanoparticles as carbon monoxide-tolerant fuel cell catalysts

et al. 2013

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Fabricating subnanometre-thick core-shell nanocatalysts is effective for obtaining high surface area of an active metal with tunable properties. The key to fully realize the potential of this approach is a reliable synthesis method to produce atomically ordered core-shell nanoparticles. Here we report new insights on eliminating lattice defects in core-shell syntheses and opportunities opened for achieving superior catalytic performance. Ordered structural transition from ruthenium hcp to platinum fcc stacking sequence at the core-shell interface is achieved via a green synthesis method, and is verified by X-ray diffraction and electron microscopic techniques coupled with density functional theory calculations. The single crystalline Ru cores with well-defined Pt bilayer shells resolve the dilemma in using a dissolution-prone metal, such as ruthenium, for alleviating the deactivating effect of carbon monoxide, opening the door for commercialization of low-temperature fuel cells that can use inexpensive reformates (H 2 with CO impurity) as the fuel. O ne major goal in electrocatalysis studies is to produce highly active, durable catalysts, while minimizing the use of precious noble metals, especially platinum (Pt). This is the key requirement for the large-scale commercialization of proton exchange membrane (PEM) fuel cells 1,2 . An effective approach is to fabricate core-shell nanoparticles (NPs) that have active, corrosion-resistant Pt atoms on the surface, with tunable reactivity through their interactions with other metal cores to assure optimal catalytic performances. At the cathode, Pt monolayer (ML) catalysts with Pd or Pd 9 Au alloy cores exhibited enhanced activity and durability for the oxygen reduction reaction compared with Pt NPs 3 . Furthermore, both experimental and theoretical studies verified that lattice contraction 4-7 , high-coordination (111) facets 8-10 and smooth surface morphology 11 are beneficial structural factors in enhancing oxygen reduction reaction activity and the catalysts' durability.For the hydrogen oxidation reaction (HOR) at the anode, a negligible overpotential loss was achieved with pure hydrogen using 50 mg cm À 2 Pt NPs 12,13 . However, the challenge remains in employing inexpensive reformate hydrogen, wherein the p.p.m.-level of carbon monoxide (CO) impurities can severely deactivate the Pt catalysts [14][15][16] . In addition, although the anode operates at relatively low potentials, its nanocatalysts must be dissolution resistant because of the high potentials experienced during startups and shutdowns 17,18 . For developing CO-tolerant HOR catalysts, ruthenium (Ru) was used to support spontaneously deposited sub-ML Pt 19,20 . With about a one-to two-ML-thick Ru(core)-Pt(shell) (denoted as Ru@Pt) NPs, theoretical calculations and temperatureprogrammed measurements showed preferential CO oxidation in hydrogen feeds on Ru@Pt NPs compared with that of Ru-Pt nano-alloys 21 and of Pt shells with other metal core 22 . Besides being a promoter of CO tolerance of Pt surface, Ru ...

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Effects of contaminants on catalyst activity

Garzón

Uribe

2010

Handbook of Fuel Cells

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Hydrogen fuel and ambient air contaminants that exhibit strong electrode catalyst chemisorption may severely degrade the performance of polymer membrane fuel cells. Common fuel‐reforming impurities include carbon monoxide and hydrogen sulfide and air impurities include sulfur oxides and nitrogen oxides. CO contamination at parts per million (ppm) levels severely affects fuel cell performance; however, a number of methods including depolarization, air bleeding, and CO tolerant catalyst alloys will mitigate the performance losses. In contrast, the deposition of S on Pt surface from adsorption of sub‐ppm levels of H 2 S in the H 2 ‐fuel stream results in severe fuel cell performance degradation. The oxidative removal of adsorbed S is a kinetically hindered process and is not achievable at reasonable rates in normal fuel cell operation.

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Study of the Exchange Current Density for the Hydrogen Oxidation and Evolution Reactions

Cited by 398 publications

References 27 publications

Understanding the electrocatalysis of oxygen reduction on platinum and its alloys

Understanding the electrocatalysis of oxygen reduction on platinum and its alloys

Ordered bilayer ruthenium–platinum core-shell nanoparticles as carbon monoxide-tolerant fuel cell catalysts

Effects of contaminants on catalyst activity

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