Nanoparticle ruthenium

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Nashner MS, Frenkel Al, Adler DL, Shapley JR, Nuzzo RG. 1997. Structural characterization of carbon supported platinum-ruthenium nanoparticles from the molecular cluster precursor PtRu5(CO)i6. J Am Chem Soc 119 7760. 

He Y, Vinodgopal K, Ashokkumar M, Grieser F (2006) Sonochemical synthesis of ruthenium nanoparticles. Res Chem Intermed 32 709-715... 

Bimetallic platinum-ruthenium nanoparticles were synthesized from the reaction of Pt(dba)2 (dba = dibenzyhdeneacetone) with Ru(COD)(COT) (COD = 1,5-cyclooctadiene COT = 1,3,5-cyclooctatriene) in various propor-... 

Gold-ruthenium nanoparticles, as heterogeneous catalyst precursors, 12, 768 Gold salts... 

Figure 12 (a) and (b) Diffraction patterns of the ruthenium nanoparticles obtained after... 

The author would like to thank his students and co-workers. A special acknowledgement is due to Dr. K. Ellmer (Hahn-Meitner-Institut-Berlin) for his help in RBS measurements. Dr. E. Savinova, and Prof. D. Kochubey (Boreskov Institut of Catalysis, Novosibirsk) for the collaboration in the EXAFS measurements via an INTAS program Dr. W. Vogel (Fritz-Haber-Institute) for the DRX measurements on ruthenium nanoparticles, and Prof. J.-M. Coustard (Poitiers University) for NMR measurements. Special thanks are also due to the staff of the Hasylab-Hamburg Synchrotron for the beam allocated to perform in-situ measurements. 

E25.17 Electrocatalysts are compounds that are capable of reducing the kinetic barrier for electrochemical reactions (barrier known as overpotential). While platinum is the most efficient electrocatalyst for accelerating oxygen reduction at the fuel cell cathode, it is expensive (recall Section 25.18 Electrocatalysis). Current research is focused on the efficiency of a platinum monolayer by placing it on a stable metal or alloy clusters your book mentions the use of the alloy PtsN. An example would be a platinum monolayer fuel-cell anode electrocatalyst, which consists of ruthenium nanoparticles with a sub-monolayer of platinum. Other areas of research include using tethered metalloporphyrin complexes for oxygen activation and subsequent reduction. 

In the case of the particles accommodating amine ligands, a new phenomenon has been evidenced, namely, a dynamic exchange at the NMR timescale between free and coordinated amines. It has been correlated to the TEM and HREM results, which show that, at the early stage of the reaction, the particles display a spherical aspect and a small size (ca. 2-3 nm), and that after a few hours, the particles coalesce into elongated wormlike particles, still constituted of pure, unoxidized hep ruthenium. This NMR observation is particularly interesting since it evidences for these particles a fluxionality similar to that of molecular clusters, which is well documented. The ruthenium nanoparticles contain coordinated mobile surface hydrides, as recently demonstrated by a combination of NMR techniques in solution, gas phase, and in the solid state. ... 

Decomposition of the organometallic precursor [Ru(cod)(cot)] (6.95) (cod =1,5-cyclopentadiene, cot= 1,3,5-cyclooctatriene) by H2 in the presence of (/ )-2-aminobu-tanol or optically-active oxazolines leads to ruthenium nanoparticles. Their properties as a catalyst for the hydrogenation of unsaturated systems have been studied, and show a weak asymmetric induction. 

To conclude, few hydrogenation studies of compounds with C=0 bonds, in particular with an asymmetric approach, have been carried out with rhodium and ruthenium nanoparticles. The development of convenient Ru and Rh colloidal suspensions for this important reaction remains a promising research area. Moreover, the investigation of modified colloids with chiral compounds is stiU a challenge for asymmetric hydrogenation of various prochiral ketones and the use of two-phase liquid-liquid systems for the recycling of chiral colloids. 

In this section, original reactions catalyzed by rhodium or ruthenium nanoparticles in various media are reported. Traditionally, these reactions were carried out in homogeneous or heterogeneous approaches. 

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