Formation and Segregation of the Ru- and Rh-MgO Solid Solutions.

Structural changes in Ru- and Rh-loaded magnesium oxide (MgO) subjected to thermal treatment were investigated by using X-ray absorption spectroscopy. The thermal treatment of the MgO-loaded Ru and Rh nanoparticles led to the formation of Ru-MgO and Rh-MgO solid solutions, respectively. The valences of Ru and Rh in the solutions were 4+ and 3+, respectively, as determined by the Ru and Rh K-edge X-ray absorption near-edge structure (XANES).

Formation and Segregation of a Pd-MgO Solid Solution Studied by X-ray Absorption Spectroscopy.

Thermal treatment of Pd nanoparticles or Pd(NH)(NO) supported on MgO resulted in the formation of a solid solution of Pd-MgO, as evidenced by Pd K-edge X-ray absorption fine structure (XAFS). The valence of Pd in the Pd-MgO solid solution was determined to be 4+ from the comparison of X-ray absorption near edge structure (XANES) with reference compounds. A characteristic shrinkage of the Pd-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.

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

Thermal treatment of Pt nanoparticles or Pt(acac) supported on MgO resulted in the formation of a solid solution of Pt-MgO, as evidenced by Pt L-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.