Formation of a Pt-MgO Solid Solution: Analysis by X-ray Absorption Fine Structure Spectroscopy

Thermal treatment of Pt nanoparticles or Pt(acac)(2) supported on MgO resulted in the formation of a solid solution of Pt-MgO, as evidenced by Pt L3-edge X-ray absorption fine structure spectroscopy. The valence of Pt in the Pt- MgO solid solution was determined to be 4+. A characteristic shrinkage of the Pt- O bond distance was observed in comparison with that of the nearest-neighboring Mg-O bond in MgO, which agreed with the density functional theory (DFT) calculations. The segregation of Pt and MgO proceeded with a further increase in the thermal treatment temperature up to 1273 K. The dispersion of Pt on MgO measured through CO adsorption was much higher than that on Al2O3 or SiO2 owing to the formation of the Pt-MgO solid solution.