Trends in der Bindungsstärke von Oberflächenspezies auf Nanopartikeln: Wie verändert sich die Adsorptionsenergie mit der Partikelgröße?

Peter, Matthias; Camacho, Jose Manuel Flores; Adamovski, Serguey; Ono, Luis K.; Dostert, Karl‐Heinz; O’Brien, Casey P.; Cuenya, Beatriz Roldán; Schauermann, Swetlana; Freund, Hans‐Joachim

doi:10.1002/ange.201209476

Cited by 12 publications

(2 citation statements)

References 31 publications

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“…Nanoparticles exhibit properties distinct from their bulk counterparts. ,, This, together with their technological relevance, − has led to a great deal of research concerning the behavior of supported Pd nanoparticles. − Recently, we have investigated the adsorption of CO on TiO 2 (110)-supported Pd nanoparticles. The Pd nanoparticles have atomically flat (111) top facets that make them amenable to study by STM.…”

Section: Introductionmentioning

confidence: 99%

Direct Visualization of Soliton CO Overlayers on Supported Pd Nanoparticles

2015

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The interaction of carbon monoxide (CO) molecules with the facets of noble metal nanoparticles forms the basis of many important catalytic reactions. Using scanning tunneling microscopy (STM), we have studied the adsorption of CO molecules on the (111) facets of Pd nanocrystals supported on a rutile TiO 2 (110) substrate. We observed four compact CO overlayers with coverages ranging between 0.5 and 0.6 monolayer. Examination of the positions of the CO molecules in each of the unit cells reveals that one of the overlayers has a rhombic R19.1˚-4CO structure. The other three form rectangular structures, namely rect-8CO, c 5 × 3 () rect-3CO and c 9 × 3 () rect-5CO. These are closely related via a soliton model previously proposed on the basis of infrared absorption spectroscopy and low energy electron diffraction. By imaging the CO molecules, we provide direct evidence for the soliton model. 7 × 7

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Section: Introductionmentioning

confidence: 99%

Direct Visualization of Soliton CO Overlayers on Supported Pd Nanoparticles

2015

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“…All these sites have been shown to play a crucial role in some reactions (10,11). Reducing the particle size can also lead to a decrease in the interatomic bond length in small metal clusters (12,13), which in the case of Pd nanoparticles results in lower adsorption energies for both CO (14,15) and O 2 (16), although such weakening of CO binding on the nanoparticle can also arise from other factors such as encapsulation of the nanoparticles by the support (17).…”

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confidence: 99%

Influence of support morphology on the bonding of molecules to nanoparticles

Yim

Pang

Hermoso

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Supported metal nanoparticles form the basis of heterogeneous catalysts. Above a certain nanoparticle size, it is generally assumed that adsorbates bond in an identical fashion as on a semiinfinite crystal. This assumption has allowed the database on metal single crystals accumulated over the past 40 years to be used to model heterogeneous catalysts. Using a surface science approach to CO adsorption on supported Pd nanoparticles, we show that this assumption may be flawed. Near-edge X-ray absorption fine structure measurements, isolated to one nanoparticle, show that CO bonds upright on the nanoparticle top facets as expected from single-crystal data. However, the CO lateral registry differs from the single crystal. Our calculations indicate that this is caused by the strain on the nanoparticle, induced by carpet growth across the substrate step edges. This strain also weakens the COmetal bond, which will reduce the energy barrier for catalytic reactions, including CO oxidation.nanoparticle | carpet growth | surface strain | adsorption | scanning tunneling microscopy N anoparticles exhibit properties distinct from their bulk counterparts (1-3). For instance, semiconductor particles smaller than ∼10 nm act as quantum dots (1-4) and oxide-supported gold nanoparticles are active for a variety of reactions including CO oxidation (5), water-gas-shift reaction (6), and epoxidation (7), whereas gold itself is not. Nanoclusters composed of ∼10 atoms have been shown to be exceptionally catalytically active for some reactions on some metals (8, 9). When the particle size is reduced, the relative number of undercoordinated atoms at the edges and corners increases. The proportion of perimeter sites at the interface between the metal and the support also increases. All these sites have been shown to play a crucial role in some reactions (10, 11). Reducing the particle size can also lead to a decrease in the interatomic bond length in small metal clusters (12, 13), which in the case of Pd nanoparticles results in lower adsorption energies for both CO (14,15) and O 2 (16), although such weakening of CO binding on the nanoparticle can also arise from other factors such as encapsulation of the nanoparticles by the support (17).The role of the support in modifying nanoparticle properties has also been recognized. For instance, the strong metal support interaction has been known for some time (2) and charge transfer either to or from the nanoparticles can lead to enhanced reactivity (18). More recently, it has come to light that the particle size itself may be governed by the interaction with the support (19). However, one effect that has not been discussed and yet should be present in any nanoparticle-support system is the influence of the support morphology such as steps.Here, we investigate the role of the support morphology on the reactivity of metal nanoparticles using scanning tunneling microscopy (STM). As our test system we choose Pd nanoparticles (20, 21) supported on TiO 2 (110) (22) simply because much is known about bo...

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Keimvermitteltes Wachstum kolloidaler Metallnanokristalle

et al. 2016

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Beim keimvermittelten Wachstum handelt es sich um eine leistungsfähige und vielseitige Vorgehensweise zur Synthese kolloidaler Metallnanokristalle. Der große Reiz dieser Methode resultiert aus dem erstaunlichen Ausmaß an Kontrolle, das über die Größe, Form, Zusammensetzung und Struktur von Nanokristallen erzielt werden kann. Diese Parameter kontrollieren nicht nur die Eigenschaften von Nanokristallen, sondern entscheiden auch über deren Relevanz und Leistungsfähigkeit in diversen Anwendungen. Das keimvermittelte Wachstum bietet hervorragende Aussichten für die Erweiterung zahlreicher Anwendungen und öffnet zugleich Türen für neue Entwicklungen. Dieser Aufsatz veranschaulicht die schier endlos erweiterbare Diversität von Metallnanokristallen auf Basis von Keimen mit genau definierten und kontrollierbaren internen Strukturen in Verbindung mit einer geeigneten Kombination aus Bedeckungsmittel und Reduktionskinetik. Darüber hinaus werden neue Einsatzmöglichkeiten und zukünftige Richtungen aufgezeigt.

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Trends in der Bindungsstärke von Oberflächenspezies auf Nanopartikeln: Wie verändert sich die Adsorptionsenergie mit der Partikelgröße?

Cited by 12 publications

References 31 publications

Direct Visualization of Soliton CO Overlayers on Supported Pd Nanoparticles

Direct Visualization of Soliton CO Overlayers on Supported Pd Nanoparticles

Influence of support morphology on the bonding of molecules to nanoparticles

Keimvermitteltes Wachstum kolloidaler Metallnanokristalle

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