[14a-2Q-1~13] 9.2 Nanowires and Nanoparticles

[14a-2Q-12] Lattice distortion and temperature factor of Ru nanoparticles revealed by Rietveld analysis using high-energy X-ray diffraction

〇(P)Chulho Song¹, Osami Sakata¹, Rosantha Kumara¹, Shiniji Kohara¹, Kohei Kusada², Hirokazu Kobayashi², Hiroshi Kitagawa² (1.NIMS/SPring-8, 2.Kyoto Univ.)

Keywords:Nanoparicle,Rietveld Analysis,High-energy XRD

Ru belongs to the 4d group of transition metals and has a hexagonal close packed (hcp) structure. It has recently been attracted much attention as a CO oxidation catalyst because of its high catalytic activity. Kusada et al. firstly reported the face-centered cubic (fcc) Ru nanoparticles obtained by a chemical reduction method in 2013, while the bulk Ru has a hcp structure. The structure and particle size can be controlled by adjusting adequate combinations of the Ru precursor and reducing agent and the catalytic activity for CO oxidation of the Ru nanoparticles supported on γ–Al₂O₃ was structure- and size-dependent. Therefore it is very important to secure an information of Ru nanoparticles depended on their structure and size.
We present the particle size dependence of structural information of Ru nanoparticles to unveil the origin of the higher activity of the fcc Ru nanoparticles. It is demonstrated that the lattice distortion is decreased with increasing particle size for hcp Ru nano particles. The lattice distortion is, however, nearly independent of particle size for fcc Ru nanoparticles and stands for the higher catalytic activity of the fcc Ru nanoparticles It is found from Rietveld analysis that the temperature factors of fcc Ru nanoparticles are larger than that of hcp Ru nanoparticles. The result can explain that the catalytic activity of the fcc Ru particles is higher than that of the hcp Ru nanoparticles and can be a key to clean up the origin of the catalytic activity for fcc and hcp Ru nanoparticles.