Ruthenium-based chalcogenides

Physico-Chemical Properties of Novel Nanocrystalline Ruthenium Based Chalcogenide Materials... 

Alonso-Vante N (2003) Physico-chemical properties of novel nanocrystalline ruthenium based chalcogenide materials. In Kokorin AI, Bahnemann DW (eds) Chemical physics of nanostructured semiconductors. VSP Brill Academic, Zeist, pp 135-152... 

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. 

Ozenler SS, Kadirgan F (2006) The effect of the matrix on the electro-catalytic properties of methanol tolerant oxygen reduction catalysts based on ruthenium-chalcogenides. J Power Sources 154 364-369... 

As an example, Fig. 5.6 depicts a typical diffraction spectrum. It is evident that long range order does not exist in our chalcogenide samples. However, the broad difffactrogram peak centered at 20 = 42.5° has the characteristic of a nanodivided ruthenium metal [22]. This points out that the active center in this chalcogenide materials is essentially of metallic nature. The material, either in powder or colloidal form, was analyzed by the EXAFS technique [11]. The local range order of this technique allowed for some structural determination of our samples. Thus, for example, the co-ordination distances for ruthenium-selenium and ruthenium-ruthenium are R(RU-se) = 2.43 A y R(ru.rU) = 2.64 A, respectively. The metal-metal co-ordination distance is of the same order of magnitude as that of well known cluster based materials such as the Chevrel phase [35, 37], cf. Fig. 5.2b. This testifies that the used chemical route leads to the formation of cluster-like materials. 

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