Iridium dioxide

Description

Iridium, atomic number 77, is a metallic element in the period 6 transition group. It is quite rare and has relatively few compounds, natural or synthetic. Despite its scarcity, it can exist in oxidation states ranging from –3 to +9.
The most common oxide of iridium by far has the +4 oxidation state: iridium(IV) oxide, or IrO2. Ir2O3 [Ir(III)] and IrO4 [Ir(VIII)] are also known. As the image shows, crystalline IrO2 adopts the rutile (TiO2) structure with iridium coordinated to six oxygen atoms.
IrO2 is prepared by heating elemental iridium or IrCl3 in the presence of oxygen. Additional heating causes the oxide to decompose into its elements. Most current IrO2 applications involve its deposition on substrates such as carbon nanotubes.
IrO2 has beneficial properties such as inertness under biological conditions and usefulness in catalysis and electrical devices. Its applications include electrodes for industrial electrolysis and regenerative fuel cells and materials for minimally invasive devices such as stents for treating coronary heart disease.

Chemical properties

BLACK POWDER

The Uses of Iridium dioxide

Iridium(IV) oxide is used in the coating of anode-electrodes for industrial electrolysis in association with other rare oxides. It is also used in microelectrodes for electrophysiology research.