Bimetallic nano-particles: featuring structure and reactivity

Guczi, L.

doi:10.1016/j.cattod.2005.01.002

Cited by 172 publications

(113 citation statements)

References 46 publications

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“…For both the 1 ML-EQ and 2ML-EQ samples, significant deviation in first-neighbor location peaks compared to metal foil are seen. This is consistent with previous reports of bulk materials [21,22]. By examining Figs.…”

Section: Evidence For Cationic Content Of Filmsupporting

confidence: 92%

Near Surface Phase Transition of Solute Derived Pt Monolayers

et al. 2013

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As the loadings of precious metals in surfacechemical systems continue to decrease for photo-and electro-catalysts for energy and environmental applications, the study of near-surface electronic and atomic structure in functional materials becomes critically important. Extremely small quantities of active elements, whether grown as clusters or ultrathin films, exhibit changes in catalytic activity that arise from both size effects and electron-transfer effects. These size and transfer effects can be related to increased propensity for oxidation of the metallic deposit, as well as to various changes in electrochemical performance such as durability or required overpotential for a given reaction. This work establishes a minimum threshold for Pt loading beyond which bulk-type electronic behavior may be expected. By iteratively growing atomic monolayers and multilayers using selflimited electrodeposition and studying these films using core-electron spectroscopy (X-ray absorption and X-ray photoelectron spectroscopy), electrochemical methods and DFT-based computations the fundamental interactions that govern oxidation state and electron transfer near the surface of a Pt-Au bimetallic system have been explored. It has been shown that the Pt-Au system exhibits increased tendency for the Pt layer to remain cationic below a minimum threshold film thickness of two monolayers. At monodispersed levels of submonolayer coverage Pt exhibits deviated electronic structure, reactivity, and metal stability compared to films in excess of this minimum threshold thickness. At three monolayers Pt is thick enough to avoid the preference for cationicity and the resulting higher rates of metal dissolution, but thin enough to benefit from electron transfers from Au that assist in lowering the overpotentials for CO oxidation. This study shows the efficacy of a concerted method for the investigation of near-surface phenomena in multicomponent systems. By combining electrochemical and vacuum studies of solutederived samples with advanced computational techniques, a multifaceted understanding of these architectures has been achieved.

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Section: Evidence For Cationic Content Of Filmsupporting

confidence: 92%

Near Surface Phase Transition of Solute Derived Pt Monolayers

et al. 2013

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“…The chemical bonds between cobalt and promoting atoms were also found using EXAFS by the groups of Holmen [52] and Davis [38] in the catalysts promoted with Re. Guczi et al [27,53] reported the presence of cobaltnoble metal bonds in CoNaY zeolite promoted with platinum. EXAFS and magnetic measurements also uncovered [54] the presence of Co-Pd bimetallic particles in the catalysts supported by niobium oxide.…”

Section: Formation Of Bimetallic Particlesmentioning

confidence: 99%

Promotion of Cobalt Fischer-Tropsch Catalysts with Noble Metals: a Review

Diehl¹,

Khodakov²

2008

Oil & Gas Science and Technology - Rev. IFP

167

109

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Résumé-Promotion par les métaux nobles de catalyseurs Fischer-Tropsch à base de cobalt : une revue -La synthèse Fischer-Tropsch est une part essentielle du procédé XTL (X-To-Liquids, avec X = Gaz, Biomasse ou Charbon) qui convertit du gaz de synthèse en hydrocarbures pour carburants propres. Les catalyseurs à base de cobalt supportés sur des oxydes inorganiques constituent le meilleur compromis pour la production de paraffines à longues chaînes carbonées et de cires. L'efficacité du procédé FischerTropsch dépend très fortement de la performance du catalyseur à base de cobalt. La promotion de ce catalyseur par des métaux précieux peut très fortement améliorer ses performances. Cet article fait la revue des différents effets des métaux nobles sur la structure et la performance de catalyseurs à base de cobalt. Les impacts sur le coût et l'activité des catalyseurs apparaissent comme des éléments incontournables dans le design de catalyseurs performants pour la synthèse Fischer-Tropsch. (X-To-Liquids, with X = Gas, Biomass or Coal) Abstract -Promotion of Cobalt Fischer-Tropsch Catalysts with Noble Metals: a Review -FischerTropsch synthesis is a major part of XTL

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“…an electronic factor due to the change in electron density) and ensemble effects (i.e. surface structure factor due to the positioning of different atom types) can contribute to synergetic effects often observed for bimetallic surface particles [6][7][8]. Enhanced dispersion and stability of gold nanoparticles on stoichiometric and reduced TiO 2 (1 1 0) were observed in the presence of molybdenum [9].…”

Section: Introductionmentioning

confidence: 99%

Structure and reactivity of Au–Rh bimetallic clusters on titanate nanowires, nanotubes and TiO2(110)

et al. 2012

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a b s t r a c tAu and Rh clusters, as well as Au-Rh bimetallic nanoparticles were prepared on titanate nanowires, nanotubes and on TiO 2 (1 1 0). They were characterized by X-ray photoelectron spectroscopy (XPS), low energy ion scattering spectroscopy (LEIS) and Fourier transform infrared spectroscopy (FTIR). By performing careful LEIS experiments, it was found that for appropriate Au and Rh coverage, a thin Au layer almost completely covers the Rh nanoparticles, a Rh core-Au shell structure was detected. The formation of this structure was not affected by alkali (K) adatoms. LEIS and FTIR measurements disclosed that adsorbed CO at 300 K causes the segregation of Rh atoms to the surface of metal clusters in order to bind to CO. Upon CO adsorption on Rh/titanate nanostructures the IR stretching frequencies characteristic of the twin form were dominant, whereas bimetallic nanosystems featured a pronounced linear stretching vibration as well. In spite of this structure adsorbed CO is detectable during the ethanol adsorption on gold-rhodium bimetallic cluster and the ethanol decomposition rate is twice higher than on Au/TiO 2 .

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Bimetallic nano-particles: featuring structure and reactivity

Cited by 172 publications

References 46 publications

Near Surface Phase Transition of Solute Derived Pt Monolayers

Near Surface Phase Transition of Solute Derived Pt Monolayers

Promotion of Cobalt Fischer-Tropsch Catalysts with Noble Metals: a Review

Structure and reactivity of Au–Rh bimetallic clusters on titanate nanowires, nanotubes and TiO2(110)

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