Formation of Ir–MgO Solid Solutions Analyzed with X-ray Absorption Spectroscopy

Abstract

Thermal treatment of MgO-loaded Ir nanoparticles or Ir(OAc)3 formed Ir–MgO solid solutions. The valence of Ir in the Ir–MgO solid solution was 3 +, as evidenced by Ir L3-edge XANES combined with XPS analysis. A slight contraction of the Ir–O bond distance was observed compared to that of the nearest neighboring Mg–O bond in MgO. Ir–MgO dispersion exhibited a two-spike pattern depending on the treatment temperature owing to the formation and successive segregation of the solid solutions.