Size-specific catalytic activity of platinum clusters enhances oxygen reduction reactions

Yamamoto, Kimihisa; Imaoka, Takane; Chun, Wang‐Jae; Enoki, Osamu; Katoh, Hideaki; Takenaga, Masahiro; Sonoi, Atsunori

doi:10.1038/nchem.288

Cited by 532 publications

(439 citation statements)

References 41 publications

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“…In 2009, by using a phenylazomethine dendrimer, Yamamoto et al successfully prepared a series of platinum clusters with a defined number of atoms [46]. The ORR activity of the Pt 12 @3, Pt 28 @3 and Pt 60 @3 (3 = phenylazomethine) clusters is shown in Table 2.…”

Section: Pt Clusters For Orrmentioning

confidence: 99%

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Tang

Wang

2018

Catalysts

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Highly-efficient catalysts for the oxygen reduction reaction (ORR) have been extensively investigated for the development of proton exchange membrane fuel cells (PEMFCs). The state-ofthe-art Pt/C catalysts suffer from high price, limited accessibility of Pt, sluggish reaction kinetics, as well as undesirable long-term durability. Engineering ultra-small noble metal clusters with high surface-to-volume ratios and robust stabilities for ORR represents a new avenue. After a simple introduction regarding the significance of ORR and the recent development of noble metal clusters, the general ORR mechanism in both acidic and basic media is firstly discussed. Subsequently, we will summarize the recent efforts employing Pt, Au, Ag, Pd and Ru clusters, as well as the alloyed bi-metallic clusters for acquiring highly efficient catalysts to enhance both the activity and stability of ORR. Molecular noble metal clusters with definitive composition to reveal the relevant ORR mechanism will be particularly highlighted. Finally, the current challenges, the future outlook, as well as the perspectives in this booming field will be proposed, featuring the great opportunities and potentials to engineering noble metal clusters as highly-efficient and durable cathodic catalysts for fuel cell applications.

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Section: Pt Clusters For Orrmentioning

confidence: 99%

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Tang

Wang

2018

Catalysts

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“…The purpose of the current study is to investigate ORR mechanisms on defective graphene−supported Pt nanoparticles using density functional theory (DFT) calculations coupled with a computational hydrogen model (CHE) 2 to provide information regarding the stability of possible intermediates within the electrochemical reaction pathways. Although metal nanoparticles used for the ORR applications are deposited on various substrates (e.g., usually carbon supports), 25,26 we compare our O 2 adsorption and reactivity results to free Pt 13 nanoparticles to demonstrate the effect of a defective graphene support on the catalytic activity of Pt 13 nanoparticles. In addition, details of the structural and electronic properties of these systems are discussed.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

2012

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The mechanisms of the oxygen reduction reaction (ORR) on defective graphene-supported Pt 13 nanoparticles have been investigated to understand the effect of defective graphene support on the ORR and predict details of ORR pathways. We employed density functional theory (DFT) predictions using the projector-augmented wave (PAW) method within the generalized gradient approximation (GGA). Free energy diagrams for the ORR over supported and unsupported Pt 13 nanoparticles were constructed to provide the stability of possible intermediates in the electrochemical reaction pathways. We demonstrate that the defective graphene support may provide a balance in the binding of ORR intermediates on Pt 13 nanoparticles by tuning the relatively high reactivity of free Pt 13 nanoparticles that bind the ORR intermediates too strongly subsequently leading to slow kinetics. The defective graphene support lowers not only the activation energy for O 2 dissociation from 0.37 to 0.16 eV, but also the energy barrier of the rate-limiting step by reducing the stability of HO* species. We predict the ORR mechanisms via direct four-electron and series two-electron pathways. It has been determined that an activation free energy (0.16 eV) for O 2 dissociation from adsorbed O 2 * at a bridge site on the supported Pt 13 nanoparticle into O* + O* species (i.e., the direct pathway) is lower than the free energy barrier (0.29 eV) for the formation of HOO* species from adsorbed O 2 * at the corresponding atop site, indicating that the direct pathway may be preferred as the initial step of the ORR mechanism. Also, it has been observed that charge is transferred from the Pt 13 nanoparticle to both defective graphene and the ORR intermediate species.

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“…Platinum is perhaps one of the most important metals in catalysis applications. Recently, it has been reported that sub-nanometer Pt [8][9][10] NCs stabilized on high-surface-area solid supports are 40-100 times more active for the oxidative dehydrogenation of propane than the previously studied platinum catalysts, 8 which is responsible for their surprisingly high surface reactivity of Pt NCs. However, very few attempts have been made at the difficult synthetic route of platinum nanoclusters (Pt NCs) in solution.…”

mentioning

confidence: 99%

Surfactant-free solution synthesis of fluorescent platinum subnanoclusters

Kawasaki¹,

Yamamoto²,

Fujimori³

et al. 2010

Chem. Commun.

122

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We have demonstrated the first surfactant-free synthesis of fluorescent Pt nanoclusters in N,N-dimethylformamide (DMF) solution. The Pt nanoclusters consist of 4 to 6 Pt atoms. They form highly stable dispersions in water, under both acidic (pH 2) and basic conditions (pH 12), and at ionic strengths of 1 M NaCl.Nobel metal clusters have recently attracted considerable attention in many areas of research, including physics, chemistry, materials science, and biosciences.1 Size-dependent effects of metal clusters are observed only when the free electrons are confined relative to the Fermi wavelength (B1 nm) in the cluster conduction band.2-7 As a result, sub-nanometer-sized metal clusters (nanoclusters) consisting of several tens of atoms are likely to exhibit molecule-like behaviors, including discrete electronic states and size-dependent fluorescence.Metal nanoclusters (NCs) are also known to possess reactivity not observed in their bulk analogs, which can make them attractive for catalysis. Platinum is perhaps one of the most important metals in catalysis applications. Recently, it has been reported that sub-nanometer Pt 8-10 NCs stabilized on high-surface-area solid supports are 40-100 times more active for the oxidative dehydrogenation of propane than the previously studied platinum catalysts, 8 which is responsible for their surprisingly high surface reactivity of Pt NCs. However, very few attempts have been made at the difficult synthetic route of platinum nanoclusters (Pt NCs) in solution.9,10 Here, we report a simple, one-pot synthesis of Pt NCs in N,N-dimethylformamide (DMF) solution in the absence of any capping agents such as surfactant, polymer, or thiolate-organic compounds. To our knowledge, this is the first successful surfactant-free chemical synthesis of fluorescent Pt NCs in solution.The preparation method described was quite simple according to a DMF reduction method for gold clusters 11 and highly reproducible. A solution of 150 mL of 0.1 M aqueous H 2 PtCl 6 was added to 15 mL of DMF that had been preheated to 140 1C, and the DMF solution was refluxed in a 140 1C oil bath with vigorous stirring for 8 h in air. As the reaction proceeded, the solution changed slowly in color from light yellow to colorless over 0 to 1 h, and finally to yellow by 2 to 6 h (Fig. 1a). The reaction was nearly complete in about 8 h, as confirmed by X-ray photoelectron spectroscopy (XPS) and by the absence of PtCl 6 À ion peaks in the UV-visible absorption spectrum. The yellow solution showed a broad UV-visible absorption below 600 nm. We found the resulting DMF solution of Pt NCs to be stable for at least six months when stored in the dark, neither precipitating nor changing in spectral properties. The Pt NCs were photoluminescent in the yellow solution after heating for more than 2 h because of their size relative to the Fermi wavelength of B1 nm, and their emission maximum depended upon the excitation wavelength (Fig. 1b). With UV excitation at 350 nm, the maximum emission wavelength was 484 nm, and with visible exc...

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Size-specific catalytic activity of platinum clusters enhances oxygen reduction reactions

Cited by 532 publications

References 41 publications

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

Mechanisms of the Oxygen Reduction Reaction on Defective Graphene-Supported Pt Nanoparticles from First-Principles

Surfactant-free solution synthesis of fluorescent platinum subnanoclusters

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