Ruthenium oxides, deposition

Zhitomirsky I, Gal-Or L (1997) Ruthenium oxide deposits prepared by cathodic electrosynthesis. Mater Lett 31 155-159... 

When a ruthenium chloride solution was electrolyzed for 500 s with a 120-mA current, 31.0 mg of ruthenium was deposited. What is the oxidation number of ruthenium in the ruthenium chloride ... 

The layer of titanium and ruthenium oxides usually is applied to a titanium substrate pyrolytically, by thermal decomposition (at a temperature of about 450°C) of an aqueous or alcoholic solution of the chlorides or of complex compounds of titanium and rathenium. The optimum layer composition corresponds to 25 to 30 atom % of ruthenium. The layer contains some quantity of chlorine its composition can be written as Ruq 2sTio 750(2- c)Cl r At this deposition temperature and Ru-Ti ratio, the layer is a poorly ordered solid solution of the dioxides of ruthenium and titanium. Chlorine is completely eliminated from the layer when this is formed at higher temperatures (up to 800°C), and the solid solution decomposes into two independent phases of titanium dioxide and ruthenium dioxide no longer exhibiting the unique catalytic properties. 

Ruthenium was recognized as a new element hy G.W. Osann in 1828. He found it in insoluhle residues from aqua regia extract of native platinum from alluvial deposits in the Ural mountains of Russia. He named it Ruthen after the Latin name Ruthenia for Russia. The discovery of this element, however, is credited to Klaus who in 1844 found that Osann s ruthenium oxide was very impure and isolated pure Ru metal from crude platinum residues insoluhle in aqua regia. 

The orange-colored solution, containing, among other things, potassium ruthenate, was treated with nitric acid, whereupon a black precipitate of osmium dioxide containing from fifteen to twenty per cent of ruthenium oxide was thrown down as a velvety deposit. Klaus distilled this with aqua regia, taking care to condense the osmium tetroxide. The residue... 

Papadatos, E, Consiglio, S., Skordas, S., Eisenbraun, E. T., Kaloyeros, A. E., Peck, J., Thompson, D. and Hoover, C. (2004), Chemical vapor deposition of ruthenium and ruthenium oxide thin films for advanced complementary metal-oxide semiconductor gate electrode applications. J. Mater. Res., 19(10) 2947-2955. 

On a more qualitative basis, from the data in Figure 17(a), it can be observed that the ruthenium-related signal does not increase linearly with the oxide loading. This may be taken as an indication that, with increasing the amount of oxide deposited, the dispersion of the phase decreases, which may be justified by accumulation of excess oxide in the valleys of the diamond surface texture and increase in the particle size. 

The combined information obtained by the different characterization methods applied allows the conclusion that deposits of ruthenium oxide at BDD, ranging from approximately one hundredth of a monolayer, maintain the physicochemical properties of RUO2, which proves the very limited degree of chemical interaction with the support. The deposits are most probably organized in nanoparticles growing around nucleation sites. When particles and clusters of particles reach a size of 50-60 nm, their charge-storage and catalytic behavior closely resembles that of thick oxide films. 

At potentials lower than the Nernst potential, the deposited Ru species consisted mainly of metallic ruthenium.4 In addition, certain amounts of ruthenium oxides, Ru02 and even Ru03, were detected. This indicates that deposition at lower potentials involved the deposition of metallic Ru, most probably according to the reactions ... 

Using the Pt( 111) electrode covered by Ru via two spontaneous depositions, it was found that a major factor determining the size of the ruthenium islands was the ruthenium oxidation state, as the size depended on the electrode potential at which the STM imaging was performed.9 An increase of the electrode potential led to an increase in the island lateral size and height. These new features may be attributed to the transformation of metallic Ru to Ru oxides.28... 

High catalyst activity and utilization of sputtered thin films was demonstrated in operating fuel cells. Optimal sputter-deposition conditions for platinum-ruthenium alloys have been determined. The effect of composition on the performance of Pt-Ru films was studied, and optimal composition has been determined. Novel methods of enhancing surface area and improving porosity have been identified. Co-sputtered ruthenium oxide has been demonstrated not to have any significant beneficial effect on the activity of the catalyst layers. While cost presents a major obstacle to commercialization of DMFCs for mobile applications, this project demonstrates novel means to reduce the catalyst costs in DFMC fuel cells. Efficiency enhancements that are also necessary for DMFCs to be viable will be addressed... 

K.S. Lyons, D.R. Rolison, Selective deposition of hydrous ruthenium oxide thin films (2003)... 

Hu C-C, Huang Y-H (1999) Cyclic voltammetric deposition of hydrous ruthenium oxide for electrochemical capacitors. J Electrochem Soc 146 2465... 

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