Oxygen Reduction on Well-Defined Core−Shell Nanocatalysts: Particle Size, Facet, and Pt Shell Thickness Effects

Wang, Jia X.; Inada, Hiromi; Wu, Lijun; Zhu, Yimei; Choi, YongMan; Liu, Ping; Zhou, Weiping; Adžić, Radoslav R.

doi:10.1021/ja9067645

Cited by 716 publications

(694 citation statements)

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“…We ascribe the latter effect to Ru-induced lattice contraction and the smooth morphology obtained both by the annealed Ru cores and by coating Pt under near-equilibrium conditions to enhance the formation of energetically favourable structure. Previous studies have shown that the less reactive a surface is, the more corrosion resistant it is 7,8,11 ; low coordination sites (clusters, defects, vertices and edges) are prone to dissolution, and thus need to be minimized 8,11 .…”

Section: Resultsmentioning

confidence: 99%

“…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][5][6][7] , high-coordination (111) facets [8][9][10] and smooth surface morphology 11 are beneficial structural factors in enhancing oxygen reduction reaction activity and the catalysts' durability.…”

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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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Section: Resultsmentioning

confidence: 99%

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

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“…Peng et al [208] also found improved stability for ORR with a Pt-on-Pd core-shell nanostructure. It was calculated that the optimal coverage of Pt on Pd (111) surface was on the order of two monolayers [271]. Yang et al [209] prepared a core-shell structure with a PdFe core and a PdPt shell, which showed four times ORR activity compared with a commercial Pt/C catalyst.…”

Section: Core-shell Structuresmentioning

confidence: 99%

Recent Development of Pd-Based Electrocatalysts for Proton Exchange Membrane Fuel Cells

2015

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This review selectively summarizes the latest developments in the Pd-based cataysts for low temperature proton exchange membrane fuel cells, especially in the application of formic acid oxidation, alcohol oxidation and oxygen reduction reaction. The advantages and shortcomings of the Pd-based catalysts for electrocatalysis are analyzed. The influence of the structure and morphology of the Pd materials on the performance of the Pd-based catalysts were described. Finally, the perspectives of future trends on Pd-based catalysts for different applications were considered.

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“…The lattice contraction will weaken the surface oxygen binding energy and reduce the coverage of intermediate oxygen species, giving rise to the enhanced ORR activity relative to the Pt nanoparticles of Pt/C and the Pt shell on the surface of Pd@Pt NDs [42,43]. Another reason can be ascribed to the relatively smooth surface feature of the NCs compared to that of the Pt/C and Pd@Pt NDs [9,44].…”

Section: Electrocatalytic Performancesmentioning

confidence: 99%

Electrochemical preparation and characterization of PdPt nanocages with improved electrocatalytic activity toward oxygen reduction reaction

Zhang

Shao

et al. 2013

Electrochimica Acta

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Oxygen Reduction on Well-Defined Core−Shell Nanocatalysts: Particle Size, Facet, and Pt Shell Thickness Effects

Cited by 716 publications

References 31 publications

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

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

Recent Development of Pd-Based Electrocatalysts for Proton Exchange Membrane Fuel Cells

Electrochemical preparation and characterization of PdPt nanocages with improved electrocatalytic activity toward oxygen reduction reaction

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