The d-Band Structure of Pt Nanoclusters Correlated with the Catalytic Activity for an Oxygen Reduction Reaction

Toyoda, Eishiro; Jinnouchi, Ryosuke; Hatanaka, Tatsuya; Morimoto, Yu; Mitsuhara, Kei; Visikovskiy, Anton; Kido, Yoshiaki

doi:10.1021/jp206360e

Cited by 137 publications

(138 citation statements)

References 27 publications

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“…The d-band centers of defective graphene-supported Pt 13 nanoparticle and free Pt 13 nanoparticle are −1.98 and −1.89 eV, respectively. This is consistent with a previous DFT calculation 26 showing −2.05 and −1.71 eV, respectively, for Pt 13 -defective graphene and free Pt 13 in a shape of icosahedrons (which is different from our distorted cuboctahedron shape of Pt 13 ). In the case of the supported Pt 13 , the d-band center is downshifted farther from E F because of the defective graphene support.…”

Section: Resultssupporting

confidence: 92%

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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Section: Resultssupporting

confidence: 92%

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

2012

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“…Analogous to the particle-size-dependent electronic effects reported in previous papers [425][426][427], the size of Ru cores can induce electronic modifications of Pt shells, affecting the electrochemical CO desorption of Ru@Pt core-shellstructured electrocatalysts. For example, Goto et al [95] reported that an Ru core 1.9 nm in size affected the lowerlying d states of weaker Pt-CO bonds on Pt shells, leading to CO desorption at less positive potentials compared with a 1.3 nm Ru core.…”

Section: Ru As Coresupporting

confidence: 52%

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Wang

Luo

et al. 2018

Electrochem. Energ. Rev.

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Pt-based catalysts are the most efficient catalysts for low-temperature fuel cells. However, commercialization is impeded by prohibitively high costs and scarcity. One of the most effective strategies to reduce Pt loading is to deposit a monolayer or a few layers of Pt over other metal cores to form core-shell-structured electrocatalysts. In core-shell-structured electrocatalysts, the compositions of the core can be divided into five classes: single-precious metallic cores represented by Pd, Ru, and Au; singlenon-precious metallic cores represented by Cu, Ni, Co, and Fe; alloy cores containing 3d, 4d or 5d metals; and carbide and nitride cores. Of these, researchers have found that carbide and nitride cores can yield tremendous advantages over alloy cores in terms of cost and promotional activities of Pt shells. In addition, desirable shells with reasonable thicknesses and compositions have been recognized to play a dominant role in electrocatalytic performances. And recently, researchers have also found that the catalytic activity of core-shell-structured catalysts is dependent on the binding energy of the adsorbents, which is determined by the d-band center of Pt. The shifting of this d-band center in turn is mainly affected by strain and electronic effects, which can be adjusted by adjusting core compositions and shell thicknesses of catalysts. In the development of these core-shell structures, optimal synthesis methods are of primary concern because they directly determine the practical application potential of the resulting electrocatalysts. And in this article, the principles behind core-shell-structured low-Pt electrocatalysts and the developmental progresses of various synthesis methods along with the traits of each type of core and its effects on Pt shell catalytic activities are discussed. In addition, perspectives on this type of catalyst are discussed and future research directions are proposed.

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“…Toyoda et al found that the catalytic activity is actually correlated with the d-band center of the Pt nanoclusters. With the decreasing of cluster size, the d-band center moves forward to the Fermi level, which enhances the oxygen adsorption energy (stronger oxygen chemisorption) [50]. The first-principle calculations indicate that the enhancement was attributed to the electronic effects and geometric effects.…”

Section: Pt Clusters For Orrmentioning

confidence: 98%

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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The d-Band Structure of Pt Nanoclusters Correlated with the Catalytic Activity for an Oxygen Reduction Reaction

Cited by 137 publications

References 27 publications

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

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

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Oxygen Reduction Reaction Catalyzed by Noble Metal Clusters

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