A metallic room-temperature oxide ion conductor

Nanoparticles of Bi3 Ir, obtained from a microwave-assisted polyol process, activate molecular oxygen from air at room temperature and reversibly intercalate it as oxide ions. The closely related structures of Bi3 Ir and Bi3 IrOx (x≤2) were investigated by X-ray diffraction, electron microscopy, and quantum-chemical modeling. In the topochemically formed metallic suboxide, the intermetallic building units are fully preserved. Time- and temperature-dependent monitoring of the oxygen uptake in an oxygen-filled chamber shows that the activation energy for oxide diffusion (84 meV) is one order of magnitude smaller than that in any known material. Bi3 IrOx is the first metallic oxide ion conductor and also the first that operates at room temperature.