rutheniumoxide

Ruthenium oxide refers to inorganic compounds containing ruthenium and oxygen. The most common oxide is ruthenium(IV) oxide, RuO2, a black solid that adopts a rutile-type structure. Other oxides include ruthenium trioxide RuO3 and ruthenium(VII) oxide RuO4, the latter being a volatile, highly oxidizing species; RuO3 is less well characterized and can form polymeric phases under some conditions. The various oxides represent ruthenium in different oxidation states, typically from +4 to +7.

RuO2 is notable for its high electrical conductivity and chemical stability. These properties make it useful as a catalytic support and as an electrode material. In catalysis, ruthenium oxides facilitate oxidation reactions, including the oxygen evolution reaction in water splitting and various organic oxidations. Thin films of RuO2 are employed in electrochemical devices such as supercapacitors and sensors, and its conductivity favors use as a resistive layer in certain microelectronic applications.

Preparation of RuO2 commonly involves direct high-temperature oxidation of ruthenium metal or its alloys in air or oxygen, yielding surface or bulk oxide. Ruthenium oxides can also be prepared by chemical routes and deposited as films by methods such as sputtering, chemical vapor deposition, or electrodeposition.

Applications and significance span catalysis, electrochemistry, and materials science. Safety considerations include the volatility and toxicity of RuO4, which requires careful handling; other ruthenium oxides are generally less hazardous but still require appropriate precautions. In nature, ruthenium oxides occur only in trace amounts and are predominantly produced synthetically.