Preferential Oxidation of Carbon Monoxide Catalyzed by Platinum Nanoparticles in Mesoporous Silica

Fukuoka, Atsushi; Kimura, Junichi; Oshio, Tadashi; Sakamoto, Yuzuru; Ichikawa, Masaru

doi:10.1021/ja0703123

Cited by 178 publications

(137 citation statements)

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“…Although the hydrogen produced via steam reforming and the water gas shift reaction contains about 1% of CO, advances were made in lowering the CO content to about 10 p.p.m. via the preferential oxidation reaction (CO þ 1/2O 2 -CO 2 in excess H 2 ) 35,36 , thus triggering a renewed interest in developing CO-tolerant fuel cell catalysts. The target for using a 10-p.p.m.…”

Section: Resultsmentioning

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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Section: Resultsmentioning

confidence: 99%

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

et al. 2013

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“…[65][66][67] However, it is difficult to control the state and interaction of the components, while the improvement in catalytic performance is also limited. 25 Very recently, a Ru-Pt core-shell (Ru@Pt) structure has been designed. 64,68 Compared with the traditional Pt-Ru alloy and mixture of monometallic particles, the core-shell structure is characteristic of confined Ru core covered with an approximately thin monolayer-thick shell of Pt atoms.…”

Section: 61mentioning

confidence: 99%

“…In term of its high energyefficiency and ultra-low emission of pollutants, the PEFC is 20 regarded as one of the most promising candidates to replace the internal combustion engine in vehicles, and power supply in stationary and portable power applications. 1 The hydrogen fuel can be produced from fossil fuels (such as natural gas and coal) and other renewable resource such as biomass, solar and 25 wind. However, in the medium term, pure hydrogen generated from renewable or sustainable energy sources will not be extensively available.…”

Section: Introductionmentioning

confidence: 99%

“…75 The surface area and dispersion of Pt nanoparticles over mesoporous silica are higher than those of conventional SiO 2 -and Al 2 O 3 -90 supported catalysts (Table 1). conversion less than 30% under the same reaction conditions, and require 423 K or even higher temperature to remove majority of CO. 25 In particular, Pt(p)/FSM-16 gives ca. 100% conversion of CO from 313 K to 423 K, 25 thus showing that this is one of the most active catalysts for PROX.…”

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confidence: 99%

“…conversion less than 30% under the same reaction conditions, and require 423 K or even higher temperature to remove majority of CO. 25 In particular, Pt(p)/FSM-16 gives ca. 100% conversion of CO from 313 K to 423 K, 25 thus showing that this is one of the most active catalysts for PROX. The (Fig.…”

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Green catalysis for selective CO oxidation in hydrogen for fuel cell

Huang

Hara

Fukuoka

2009

Energy Environ. Sci.

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5Preferential oxidation of carbon monoxide in excess hydrogen (PROX) is one of the key processes for the production of clean hydrogen fuel for the polymer electrolyte membrane fuel cell (PEFC). Development of highly active and selective catalysts is among the most challenging works for decades. Platinum-based catalysts are regarded as the most promising candidates for this process. However, the activities of Pt catalysts seriously suffer from the strong poisonous adsorption by CO 10 substrate at low reaction temperature. This article addresses the present approaches to improve the catalytic performance under the low temperature. The focus in this article is the finding over the Pt/mesoporous silica catalyst. The high activity and selectivity of this catalyst has been attributed to the surface silanols in mesoporous silica. The perspectives of Pt/mesoporous silica in the PROX reaction are also presented.

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Active Ensemble Structures for Selective Oxidation Catalyses at Surfaces

Tada

Iwasawa

2009

Modern Heterogeneous Oxidation Catalysis

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Preferential Oxidation of Carbon Monoxide Catalyzed by Platinum Nanoparticles in Mesoporous Silica

Cited by 178 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

Green catalysis for selective CO oxidation in hydrogen for fuel cell

Active Ensemble Structures for Selective Oxidation Catalyses at Surfaces

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