Thermal and photochemical reactivity of oxygen atoms on gold nanocluster surfaces

Taketoshi Matsumoto, Patricia Nickut, Hironori Tsunoyama, Kazuya Watanabe, Tatsuya Tsukuda, Katharina Al-Shamery, Yoshiyasu Matsumoto

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Reduction of oxidized gold nanoclusters by exposures to foreign gases and irradiation of UV photons has been investigated using X-ray photoelectron spectroscopy. Gold nanoclusters with narrow size distributions protected by alkanethiolate ligands were deposited on a TiO2(1 1 0) surface with dip coating. Oxygen plasma etching was used for removal of alkanethiolate ligands and oxidization of gold clusters. The oxidized gold clusters were exposed to CO, C2H2, C2H4, H2, and hydrogen atoms. Although, C2H4 and H2 did not show any indications of reduction of oxidized gold clusters, CO, C2H2, and hydrogen atoms reduced the oxides on gold cluster surfaces. Among them, hydrogen atoms were most effective for reduction. Irradiation of UV photons around 400 nm could also reduce the oxidized gold clusters. The photochemical reduction mechanism was proposed as follows. The photo-reduction was initiated by electronic excitation of gold clusters and oxygen atoms activated reacted with carbon atoms at the surfaces of gold clusters. Carbon species were likely absorbed in gold clusters or remained at the boundaries between gold clusters when gold clusters agglomerated during oxygen plasma exposures. As the photochemical reduction progressed, carbon atoms segregated to the surfaces of gold clusters.

Original languageEnglish
Pages (from-to)5226-5231
Number of pages6
JournalSurface Science
Volume601
Issue number22
DOIs
Publication statusPublished - 2007 Nov 15

Keywords

  • Acetylene
  • Carbon monoxide
  • Gold
  • Hydrogen
  • Oxides
  • Photochemistry
  • Titanium oxide
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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