Nanostructured Iridium Oxide: State of the Art

Abstract

Iridium Oxide (IrO2) is a metal oxide with a rutile crystalline structure, analogous to the TiO2 rutile polymorph. Unlike other oxides of transition metals, IrO2 shows a metallic type conductivity and displays a low surface work function. IrO2 is also characterized by a high chemical stability. These highly desirable properties make IrO2 a rightful candidate for specific applications. Furthermore, IrO2 can be synthesized in the form of a wide variety of nanostructures ranging from nanopowder, nanosheets, nanotubes, nanorods, nanowires, and nanoporous thin films. IrO2 nanostructuration, which allows its attractive intrinsic properties to be enhanced, can therefore be exploited according to the pursued application. Indeed, IrO2 nanostructures have shown utility in fields that span from electrocatalysis, electrochromic devices, sensors, fuel cell and supercapacitors. After a brief description of the IrO2 structure and properties, the present review will describe the main employed synthetic methodologies that are followed to prepare selectively the various types of nanostructures, highlighting in each case the advantages brought by the nanostructuration illustrating their performances and applications.