Iridium(IV) oxide, IrO
2, is the only well-characterised oxide of iridium. It is a blue-black solid. The compound adopts the TiO
2 rutile structure
Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.
Rutile has one of the highest refractive indices at visible wa ...
, featuring six coordinate iridium and three coordinate oxygen.
It is used with other rare oxides in the coating of anode-electrodes for industrial electrolysis and in
microelectrodes for
electrophysiology research.
As described by its discoverers, it can be formed by treating the green form of
iridium trichloride
Iridium(III) chloride is the inorganic compound with the formula IrCl3. The anhydrous compound is relatively rare, but the related hydrate is useful for preparing other iridium compounds. The anhydrous salt is a dark green crystalline solid. ...
with oxygen at high temperatures:
:2 IrCl
3 + 2 O
2 → 2 IrO
2 + 3 Cl
2
A hydrated form is also known.
Application
Iridium dioxide can be used as an anode electrode for industrial electrolysis and as a microelectrode for electrophysiological studies.
Iridium dioxide can be used to make coated electrodes.
References
Iridium compounds
Transition metal oxides
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