Ruthenium dioxide conductivity

Recently it has been shown that the oxides of the platinum metals can have a higher corrosion resistance than the metals themselves , and have sufficient conductivity to be used as coatings for anodes, e.g. with titanium cores. Anodes with a coating of ruthenium dioxide are being developed for use in mercury cells for the electrolysis of brine to produce chlorine , since they are resistant to attack if in contact with the sodium-mercury amalgam. 

Titanium dioxide is a catalytically inactive but rather corrosion-resistant material. Ruthenium dioxide is one of the few oxides having metal-like conductivity. It is catalytically quite active toward oygen and chlorine evolution. However, its chemical stability is limited, and it dissolves anodically at potentials of 1.50 to 1.55 V (RHE) with appreciable rates. A layer of mixed titanium and ruthenium dioxides containing 1-2 mg/cm of the precious metal has entirely unique properties in terms of its activity and selectivity toward chlorine evolution and in terms of its stability. With a working current density in chlorine evolution of 20 to 50mA/cm, the service life of such anodes is several years (up to eight years). 

Ruthenium dioxide has been of recent interest for use as a conductive material in microelectronics devices. A range of precursors has been used for the growth of ruthenium-containing thin-film materials, including Ru(tmhd)3, ... 

The functional phase in thick-film resistors is a mixture of electrically conducting (or semiconducting) ceramic powders such as ruthenium dioxide (RUO2), bismuth ruthenate (Bi2Ru207), lead ruthenate (Pb2Ru206), and Ag-Pd-PdO mixtures for use in air-fired pastes and tantalum nitride (TaN) for nitrogen-fired pastes. The resistance of thick-film resistors is specified in terms of sheet resistance, which has units of ohms/square (Q/D). 

As the electrol d e solution, concentrated acidic, or alkaline media, for example, H2SO4, KOH solution, are often utilized for the carbon and ruthenium dioxide supercapacitor because ofthe superior ionic conductivity. Manganese dioxides are, however, soluble in the acidic... 

Liao YH, Chou JC (2008) Comparison of polypyrrole-conducting polymer and Ag/AgCl reference electrodes Used for ruthenium dioxide pH electrode. J Electrochem Soc 155 ... 

The decomposition of sugars in a photolytic process in the presence of ruthenium(IV) and titanium(IV) oxides and of platinum has been described. This process, conducted in an aqueous solution, eventually in the presence of alkali, yields hydrogen and carbon dioxide. ... 

Ruthenium-catalyzed asymmetric addition of alkane- or arenesulfonyl chlorides to styrenes leads to optically active suifones22,23. When this conversion is conducted under mild conditions no C —C bond is formed, however, at higher temperatures (100 =C), enantioselective asymmetric carbohalogenation of styrene with trichloromethanesulfonyl chloride (accompanied by sulfur dioxide extrusion) can be achieved with tetrachlorotris[( + )- or (—)-Diop]diruthenium. Excellent yields (up to 100%), but only low asymmetric inductions (up to 13 %), arc observed12. Similar results are obtained with carbon tetrachloride. A mechanism with radical formation w ithin the metal coordination sphere ( radicaloid ) has been proposed. 

In principle, the theory of reversible electrodes can serve as the basis for developing the thermodynamic approach to the surface electrochemistry of oxide materials with metalhc conductivity (iridium, ruthenium, tin dioxides, and so on) [100]. In addition, the properties of these interfaces can be considered within the framework of three models the classical model of bound sites [101], which can be modified by considering several types of surface groups... 

The reaction is insensitive to whether the atmosphere used is dinitrogen or carbon monoxide. The iron complex Fe3(PPh3)2 proved to be much less. active than its ruthenium analogue in this reaction. Analyses o-f the gas evolved during the catalytic reactions conducted under dinitrogen have shown the -formation o-f carbon dioxide, but its quantity was less than calculated on the basis o-f the PhNO converted. On the other hand, in protic media the reaction could proceed via the proton trans-fer -from the solvent to n i trosobenzene, with the intermediate formation o-f hydroxyl ami ne s... 

Platinum anodes have a limited operational range of oxidation potentials and thus attention has focused on Sn02-coated titanium materials. The tin oxide material, when doped with Sb (approximately 5%) to impart the appropriate electrical conductivity, has oxygen overpotentials some 600 mV greater than those of platinum. Tin oxide gives higher oxidation efficiencies to those of platinum, lead dioxide, ruthenium and iridium oxide (DSA) electrodes and is reported to be stable to corrosion during anodic oxidation. 

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