Ruthenium selenides

N. Alonso-Vante, S. Cattarin, M. Musiani, Electrocatalysis of O2 reduction at polyaniline + molybdenum-doped ruthenium selenide composite electrodes. J. Electro-anal. Chem. 2000, 481, 200-207. 

Raez A, Bele P, Cremers C, Stimming U (2007) Ruthenium selenide catalysts for cathodic oxygen reduction in direct methanol fuel cells. J Appl Electrochem 37 1455-1462... 

In order to understand the growth of metal clusters in solution, one should start from a metal complex precursor, such as [My(CO)x], according to Eq. (1). The precursor can be generated in situ. The protocol synthesis of such a chemical precursor is represented by the flow-chart see Fig. 4 for the case of ruthenium-selenide. This flow chart summarizes the synthesis initially reported in 1991, " and it will be taken as the template for similar compounds. A careful follow-up of the reaction was made by means of the Indeed, following the synthesis without carbon, i.e., after step 3, a heteronuclear chemical precursor was identified Ru4Se2(CO)3(CO)g. The ongoing reaction under the boiling point of the solvent for 20 hours led to a complete pyrolysis of the heteronuclear molecular cluster compound to nanopowders of... 

Figure 4. Flow-chart indicating the various steps of the ruthenium-selenide RuxSey clus-ter-like material synthesis either nonsupported or carbon supported. Bottom TEM pictures of the corresponding end-products.

Figure 9. The use of the template in Fig. 4 led to another chemical route of ruthenium-selenide synthesis using water as a solvent. Bottom TEM picture of the corresponding product.

The coordination distances for ruthenium-selenium and ruthenium-rathenium are, respectively R(Ru-se) = 2.43 A y R(ru-ru) = 2.64 A. In in situ EXAFS measurements, ruthenium-selenide presented some distortion induced by the oxygen adsorption. This was discussed as being the precondition to break the 0-0 bond favoring thus the... 

Fig. 14.10 Calculated mol % of H2O2 as a flmclion of the specific mass loading at the same ratio of catalyst to carbon at a defined electrode potential. For the ruthenium-selenide system, the data (Jilled circles) were extracted from ref. [70], for o-CoSeJC (filled squares) fi om ref [45], for c-CoSe2/C (half-filled squares) fi om ref [56], and data shown in the inset for Fe-C-N (Jilled triangles) from ref [71]...

Alonso-Vante, N., Cattarin, S. and Musiani, M. (2000). Electrocatalysis of O2 Reduction at Polyaniline + Molybdenum-doped Ruthenium Selenide Composite Electrodes, J. Electroanal. Chem., 481, pp. 200-207. 

Binary systems of ruthenium sulfide or selenide nanoparticles (RujcSy, RujcSey) are considered as the state-of-the-art ORR electrocatalysts in the class of non-Chevrel amorphous transition metal chalcogenides. Notably, in contrast to pyrite-type MS2 varieties (typically RUS2) utilized in industrial catalysis as effective cathodes for the molecular oxygen reduction in acid medium, these Ru-based cluster materials exhibit a fairly robust activity even in high methanol content environments of fuel cells. 

Phenyl selenides.2 In the presence of a ruthenium catalyst, prepared by reaction of RuCly with 3 equivalents of potassium, lithium benzencselenolate reacts with a wide variety of tertiary amines to form phenyl selenides in excellent yield. Anhydrous diglyme is used as solvent. 

The oxidation of selenoxides to selenones is slow requiring drastic conditions to be used. Diaryl, aryl methyl and dimethyl selenones are prepared by the oxidation of the ctxresponding selenoxides with prolonged exposure to KMn04 or ozone. The direct oxidation of selenides to selenones by FWO with ruthenium(II) complex catalyst, and C u(Mn04)2 has also been described. Aiyl trifluo-... 

Sodium periodate (sodium metaperiodate), NaI04 (mp 300 °C dec), which is commercially available, is applied mainly in aqueous or aqueous-alcoholic solutions. Like the free periodic acid, sodium periodate cleaves vicinal diols to carbonyl compounds [762], This reaction is especially useful in connection with potassium permanganate [763, 764] or osmium tetroxide [765], Such mixed oxidants oxidize alkenes to carbonyl compounds or carboxylic acids, evidently by way of vicinal diols as intermediates. Sulfides are transformed by sodium periodate into sulfoxides [322, 323, 766, 767, 768, 769, 770, 771, 772], and selenides are converted into selenoxides [773]. Sodium periodate is also a reoxidant of lower valency ruthenium in oxidations with ruthenium tetroxide [567, 774],... 

Interestingly, alkyl groups on amines can be employed for the synthesis of unsymmetrical selenides in the presence of ruthenium catalysts prepared by the reduction of RuCls with potassium (Scheme 15.78) [159]. 

M. F. Ilker, H. Skalf, T. Emrick and E.B. Coughlin, Metathesis and Polyolefin Growth on Cadmium Selenide Surfaces Using Ruthenium-Based Catalysts , p. 263... 

The development of a new generation of catalysts and semiconductors will be needed if a photochemical process (using solar radiation) is to be viable, but research and development in this area is growing rapidly. The sources of hydrogen include hydrocarbons, alcohols, and organic acids. Ruthenium, rhodium, and iridium catalysts, and various arsenide, selenide, and telluride semiconductors (see Chapter 15), may lead the way to an efficient system. 

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