Alkylamine Stabilized Ruthenium Nanocrystals: Faceting and Branching

Brink, Miranda Vanden; Peck, Matthea A.; More, Karren L.; Hoefelmeyer, James D.

doi:10.1021/jp801546c

Cited by 29 publications

(19 citation statements)

References 29 publications

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“…This order appears to have a correlation with the electron-donating ability of the R group (except that there was leveling off of the mass activities in the cases of hydroxy and carboxylic groups, which is presumably due to attainment of mass limitation over these high-surface-area SWNT materials). Although it would be expected that amine groups would give the highest electrondonating ability to the Pd metal nanoparticles than any of the other functional groups when they are in neutral form, [16] it is evident from this study that the carboxylic acid and phenolic acid moieties gave a higher mass activity than the amine. It should be borne in mind that under the high-pH synthesis, these species will be totally ionized (as phenolate or carboxylate with potassium ions in solid forms, even when placed in acidic solution), and therefore be more strongly electron-donating.…”

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confidence: 62%

Electron Promotion by Surface Functional Groups of Single Wall Carbon Nanotubes to Overlying Metal Particles in a Fuel‐Cell Catalyst

et al. 2012

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A remarkable promotion: Functional groups added onto single-wall carbon nanotubes (SWNTs) can significantly influence the activity of a noble metal for formic acid oxidation. Phenolate groups on SWNTs under alkaline conditions can double the activity of 20 % w/w Pd compared to unmodified SWNTs. This catalyst has 14 times higher activity than the commercial benchmark catalyst (10 % w/w Pd on Vulcan).

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confidence: 62%

Electron Promotion by Surface Functional Groups of Single Wall Carbon Nanotubes to Overlying Metal Particles in a Fuel‐Cell Catalyst

et al. 2012

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“…40 The hydrogen evolution rate for RuO 2 /TiO 2 was found to be 30 times higher than that for TiO 2 alone and sensitive to increasing amounts of RuO 2 reaching a maximum at 0.4 × 10 −3 molar ratio of RuO 2 /TiO 2 . Ruthenia nanoparticles here act as electron pools (reducing sites) 41 while titania is an oxidizing electrode, i.e. hydrogen and oxygen evolution takes place on ruthenia nanoparticles and titania, respectively.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Charge Transfer from Titania to Surface Doping Site

2013

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We evaluate a theoretical model in which Ru is substituting for Ti at the (100) surface of anatase TiO2. Charge transfer from the photo-excited TiO2 substrate to the catalytic site triggers the photo-catalytic event (such as water oxidation or reduction half-reaction). We perform ab-initio computational modeling of the charge transfer dynamics on the interface of TiO2 nanorod and catalytic site. A slab of TiO2 represents a fragment of TiO2 nanorod in the anatase phase. Titanium to ruthenium replacement is performed in a way to match the symmetry of TiO2 substrate. One molecular layer of adsorbed water is taken into consideration to mimic the experimental conditions. It is found that these adsorbed water molecules saturate dangling surface bonds and drastically affect the electronic properties of systems investigated. The modeling is performed by reduced density matrix method in the basis of Kohn-Sham orbitals. A nano-catalyst modeled through replacement defect contributes energy levels near the bottom of the conduction band of TiO2 nano-structure. An exciton in the nano-rod is dissipating due to interaction with lattice vibrations, treated through non-adiabatic coupling. The electron relaxes to conduction band edge and then to the Ru cite with faster rate than hole relaxes to the Ru cite. These results are of the importance for an optimal design of nano-materials for photo-catalytic water splitting and solar energy harvesting.

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“…This is due to the fact that the ES is determined by the anisotropy in surface free energies (SFE) of different faces, which can be modified by adsorbates. 9 Therefore, the performance of NPs can depend strongly on their chemical environment due to adsorbate-induced shape changes.…”

Section: Introductionmentioning

confidence: 99%

Structure-activity relation of Re nanoparticles

Kaghazchi¹,

Jacob²

2012

Phys. Rev. B

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By combining density functional theory and thermodynamic considerations we determined the equilibrium shape of Re particles in contact with O 2 and N 2 environments. At low and intermediate coverages oxygen adsorption has a minor influence on the particle shape, while nitrogen adsorption leads to the stabilization of spherically shaped polyhedra with a large contribution from atomically rough faces. At very high coverages of O and N particles are perfect prisms consisting of low-index faces. By comparing these results with the experimental data for the activity of different Re surfaces we propose that the experimentally measured high initial activity of polycrystalline Re for ammonia synthesis might be due to the N-induced formation of high-index faces with a high density of low-coordinated atoms (roughening). Moreover, the measured decrease in the activity of polycrystalline Re at saturation coverage might be because of the N-induced formation of close-packed faces (smoothing). Our calculations suggest that adsorbate-induced roughening or smoothing of catalytic particles on the atomic scale is capable of controlling the activity of the catalysts.

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Alkylamine Stabilized Ruthenium Nanocrystals: Faceting and Branching

Cited by 29 publications

References 29 publications

Electron Promotion by Surface Functional Groups of Single Wall Carbon Nanotubes to Overlying Metal Particles in a Fuel‐Cell Catalyst

Electron Promotion by Surface Functional Groups of Single Wall Carbon Nanotubes to Overlying Metal Particles in a Fuel‐Cell Catalyst

Photoinduced Charge Transfer from Titania to Surface Doping Site

Structure-activity relation of Re nanoparticles

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