Stable low-valence ReO x cluster attached on Rh metal particles formed by hydrogen reduction and its formation mechanism

Shuichi Koso, Hideo Watanabe, Kazu Okumura, Yoshinao Nakagawa, Keiichi Tomishige

Research output: Contribution to journalReview articlepeer-review

65 Citations (Scopus)


The structural change of ReO x/SiO 2, Rh/SiO 2, and Rh-ReO x/SiO 2 during the temperature programmed reduction with H 2 was investigated using in situ Re L 3-edge and Rh K-edge quick-scanning X-ray absorption fine structure. Monometallic ReO x/SiO 2 was reduced at about 600 K to form Re metal particles covered with partially oxidized Re species. In contrast, in the case of Rh-ReO x/SiO 2 (Re/Rh = 0.5), the reduction of Rh proceeded to give highly dispersed Rh metal particles at first (∼325 K), and then Re was reduced mildly (∼365 K). The reduced Re species interacted with the Rh metal surface and were highly dispersed. At higher reduction temperature (∼595 K), these Re-modified Rh metal particles aggregated and further reduction of Re to low-valence state proceeded on the Rh metal surface. The low-valence Re interacting with Rh metal surface comprises two-dimensional Re oxide clusters. No detection of Re metal or Rh-Re alloy formation even after reduction at high temperature (595 K) suggests that the two-dimensional ReO x clusters on the Rh metal surface are highly stable.

Original languageEnglish
Pages (from-to)3079-3090
Number of pages12
JournalJournal of Physical Chemistry C
Issue number4
Publication statusPublished - 2012 Feb 2

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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