Effects of Cluster Size on Platinum–Oxygen Bonds Formation in Small Platinum Clusters

Oemry, Ferensa; Padama, Allan Abraham B.; Kishi, Hirofumi; Kunikata, Shinichi; Nakanishi, Hiroshi; Kasai, Hideaki; Maekawa, Hiroyoshi; Osumi, Kazuo; Sato, Kaoru

doi:10.7567/jjap.51.035002

Cited by 9 publications

(11 citation statements)

References 40 publications

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“…546 In the other DFT study, the tetragonal shape remains largely intact. 547 Although thermodynamically favorable, O 2 dissociation might be kinetically limited on the smallest clusters. For the flat Pt 5 cluster, the calculated barrier is 0.66 eV, higher than for the extended Pt (111) surface.…”

Section: O On Ptmentioning

confidence: 98%

“…Two different adsorption geometries of both O 2 and O on the Pt 4 and Pt 10 clusters were proposed based on DFT calculations. 546,547 In one study, the tetragonal-shaped cluster strongly deforms upon adsorption, even becoming flat for the Pt 4 cluster. 546 In the other DFT study, the tetragonal shape remains largely intact.…”

Section: O On Ptmentioning

confidence: 99%

“…Small (2n with n = 1−6) clusters of Pt and Pd are energetically inclined to dissociate O 2 based on DFT studies. 546,547 Compared to the extended Pt (111) surface, the binding of O is increased by 0.5 eV per O atom. 546 The adsorption geometry is different from that on the extended surface, as the clusters prefer to bridge O between two Pt atoms.…”

Section: O On Ptmentioning

confidence: 99%

“…548 For tetragonally shaped clusters, a lower barrier of 0.17 eV was calculated for Pt 4 , while O 2 dissociation on Pt 10 was barrierless. 547 The reactivity of the latter was related to the flexibility of the cluster to adapt its geometry to the dissociating O 2 molecule.…”

Section: O On Ptmentioning

confidence: 99%

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O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

et al. 2017

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The activation of O on metal surfaces is a critical process for heterogeneous catalysis and materials oxidation. Fundamental studies of well-defined metal surfaces using a variety of techniques have given crucial insight into the mechanisms, energetics, and dynamics of O adsorption and dissociation. Here, trends in the activation of O on transition metal surfaces are discussed, and various O adsorption states are described in terms of both electronic structure and geometry. The mechanism and dynamics of O dissociation are also reviewed, including the importance of the spin transition. The reactivity of O and O toward reactant molecules is also briefly discussed in the context of catalysis. The reactivity of a surface toward O generally correlates with the adsorption strength of O, the tendency to oxidize, and the heat of formation of the oxide. Periodic trends can be rationalized in terms of attractive and repulsive interactions with the d-band, such that inert metals tend to feature a full d band that is low energy and has a large spatial overlap with adsorbate states. More open surfaces or undercoordinated defect sites can be much more reactive than close-packed surfaces. Reactions between O and other species tend to be more prevalent than reactions between O and other species, particularly on more reactive surfaces.

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Section: O On Ptmentioning

confidence: 98%

Section: O On Ptmentioning

confidence: 99%

Section: O On Ptmentioning

confidence: 99%

Section: O On Ptmentioning

confidence: 99%

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O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

et al. 2017

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“…Owing to the fact that atomic oxygen can easily diffuse into the inner shell of nano‐Pt, resulting in the growth of surface oxides via interface oxidization, such oxidizability of superficial atoms would be dramatically increased with increasing active sizes. In other words, when the size of individual nano‐Pt particles is shrunk to ≈1 nm, at least 76% of the Pt atoms on the surface are exposed, meaning that the coverage of surface oxides on such particles would be higher than those of large size nano‐Pt . With such oxidization and subsequent dissolution in the acidic organelles (i.e., endosomes/lysosomes) of cells, a typical corrosion process similar to that of silver nanoparticles would be triggered .…”

Section: Introductionmentioning

confidence: 99%

Corrosion‐Activated Chemotherapeutic Function of Nanoparticulate Platinum as a Cisplatin Resistance‐Overcoming Prodrug with Limited Autophagy Induction

Cheng

Chien

et al. 2016

Small

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Despite nanoparticulate platinum (nano-Pt) has been validated to be acting as a platinum-based prodrug for anticancer therapy, the key factor in controlling its cytotoxicity remains to be clarified. In this study, it is found that the corrosion susceptibility of nano-Pt can be triggered by inducing the oxidization of superficial Pt atoms, which can kill both cisplatin-sensitive/resistance cancer cells. Direct evidence in the oxidization of superficial Pt atoms is validated to observe the formation of platinum oxides by X-ray absorption spectroscopy. The cytotoxicity is originated from the dissolution of nano-Pt followed by the release of highly toxic Pt ions during the corrosion process. Additionally, the limiting autophagy induction by nano-Pt might prevent cancer cells from acquiring autophagy-related drug resistance. With such advantages, the possibility of further autophagy-related drug resistance could be substantially reduced or even eliminated in cancer cells treated with nano-Pt. Moreover, nano-Pt is demonstrated to kill cisplatin-resistant cancer cells not only by inducing apoptosis but also by inducing necrosis for pro-inflammatory/inflammatory responses. Thus, nano-Pt treatment might bring additional therapeutic benefits by regulating immunological responses in tumor microenvironment. These findings support the idea that utilizing nano-Pt for its cytotoxic effects might potentially benefit patients with cisplatin resistance in clinical chemotherapy.

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Stability of Ni Clusters and the Adsorption of CH₄: First-Principles Calculations

Rodríguez‐Kessler

Rodríguez-Domínguez

2015

J. Phys. Chem. C

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Structural, magnetic and adsorption properties of Ni n (n = 2−16, 21, 55) clusters have been investigated based on density funciontal theory (DFT) with the spin polarized generalized gradient approximation, using the Perdew−Burke−Ernzerhof functional. The most stable isomers have been selected to study the adsorption of methane CH 4 and methyl CH 3 . It is found that the CH 4 molecule adsorbs on the top site for all clusters considered. The most selective Ni n clusters are the tetrahedron (n = 4) and icosahedral clusters due to highcoordinated edge atoms (n = 13, 21, and 55). For CH 3 , stronger adsorption tendencies were found with similar patterns. Our results show that clusters with n = 6, 10, and 13 with complete atomic shells are relatively more stable. Besides, they perform the lowest adsorption for CH 3 , indicating that they possess such a desirable property of a higher carbon poisoning resistance, than for the rest of the clusters. This result can be understood in terms of the electronic stability and localization of the frontier molecular orbitals. ■ INTRODUCTIONSmall clusters and nanoparticles have been widely studied in the past few years due to their high surface to volume ratio and enhanced reactivity properties compared with their bulk counterparts. 1 For example, gold nanoparticles are active catalyts although gold in the bulk is practically inert. 2,3 In catalytic reactions, they usually increase the selectivity and bond dissociation steps since they have more edge sites and lowcoordinated atoms. 4 Although in some reactions the presence of edge sites on the surface of nanoparticles can reduce the specific catalytic activity, 5 they are useful for different reactions, such as decomposition of hydrocarbons and alcohols, which can serve as important hydrogen sources. 6,7 Recently, much attention has been paid to the hydrogen production relating to the fuel cell technology. 8 In practice, hydrogen is produced from natural gas via steam reforming of methane, a process highly endothermic and very expensive, due to the high heat demand. 9 Among a wide range of heterogeneous catalyst, noble metal catalysts show higher activity and stability for this reaction, but the prohibitive cost and scarce resources makes their use very limited. On the other hand, Ni-based are promising catalysts in terms of cost and outstanding activity compared with noble-metals. However, the major problem of Ni-based systems is the strongly bonded carbon deposition on the catalyst surface which can deactivate the catalyst reducing its stability. 10 In a previous work, 11 we have shown that small Rh clusters possess an excellent selectivity to catalytically adsorb and dissociate the acid rain precursor N 2 O molecule. Furthermore, in the limit of going to arbitrary large clusters, it was interesting to compare this effect with that of a flat (111) slab of same metal, which happened to be provided with a much more smaller selectivity as the corresponding to small clusters. The problem, however, appears when we begin to consider cl...

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Effects of Cluster Size on Platinum–Oxygen Bonds Formation in Small Platinum Clusters

Cited by 9 publications

References 40 publications

O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

Corrosion‐Activated Chemotherapeutic Function of Nanoparticulate Platinum as a Cisplatin Resistance‐Overcoming Prodrug with Limited Autophagy Induction

Stability of Ni Clusters and the Adsorption of CH₄: First-Principles Calculations

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Effects of Cluster Size on Platinum–Oxygen Bonds Formation in Small Platinum Clusters

Cited by 9 publications

References 40 publications

O2 Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

O2 Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

Corrosion‐Activated Chemotherapeutic Function of Nanoparticulate Platinum as a Cisplatin Resistance‐Overcoming Prodrug with Limited Autophagy Induction

Stability of Ni Clusters and the Adsorption of CH4: First-Principles Calculations

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Product

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O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

O₂ Activation by Metal Surfaces: Implications for Bonding and Reactivity on Heterogeneous Catalysts

Stability of Ni Clusters and the Adsorption of CH₄: First-Principles Calculations