title: Size dependence of structural parameters in fcc and hcp Ru nanoparticles, revealed by Rietveld refinement analysis of high-energy X-ray diffraction data.
abstract: To reveal the origin of the CO oxidation activity of Ruthenium nanoparticles (Ru NPs), we structurally characterized Ru NPs through Rietveld refinement analysis of high-energy X-ray diffraction data. For hexagonal close-packed (hcp) Ru NPs, the CO oxidation activity decreased with decreasing domain surface area. However, for face-centered cubic (fcc) Ru NPs, the CO oxidation activity became stronger with decreasing domain surface area. In comparing fcc Ru NPs with hcp Ru NPs, we found that the hcp Ru NPs of approximately 2 nm, which had a smaller domain surface area and smaller atomic displacement, showed a higher catalytic activity than that of fcc Ru NPs of the same size. In contrast, fcc Ru NPs larger than 3.5 nm, which had a larger domain surface area, lattice distortion, and larger atomic displacement, exhibited higher catalytic activity than that of hcp Ru NPs of the same size. In addition, the fcc Ru NPs had larger atomic displacements than hcp Ru NPs for diameters ranging from 2.2 to 5.4 nm. Enhancement of the CO oxidation activity in fcc Ru NPs may be caused by an increase in imperfections due to lattice distortions of close-packed planes and static atomic displacements.
authors: Synchrotron X-ray Station at SPring-8, Research Network and Facility Services Division, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors: Chulho
authors: C
authors: Song
authors: Synchrotron X-ray Station at SPring-8, Research Network and Facility Services Division, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.|Synchrotron X-ray Group, Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.|Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259-J3-16, Nagatsuta, Midori, Yokohama 226-8502, Japan.
authors: Osami
authors: O
authors: Sakata
authors: Synchrotron X-ray Station at SPring-8, Research Network and Facility Services Division, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors: Loku Singgappulige Rosantha
authors: LS
authors: Kumara
authors: Synchrotron X-ray Station at SPring-8, Research Network and Facility Services Division, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.|Synchrotron X-ray Group, Research Center for Advanced Measurement and Characterization, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors: Shinji
authors: S
authors: Kohara
authors: Synchrotron X-ray Station at SPring-8, Research Network and Facility Services Division, National Institute for Materials Science, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
authors: Anli
authors: A
authors: Yang
authors: Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
authors: Kohei
authors: K
authors: Kusada
authors: Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
authors: Hirokazu
authors: H
authors: Kobayashi
authors: Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.|Institute for Integrated Cell-Material Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.|INAMORI Frontier Research Center, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-3095, Japan.
authors: Hiroshi
authors: H
authors: Kitagawa