Carrier dynamics in TiO2 and Pt/TiO2 powders observed by femtosecond time-resolved near-infrared spectroscopy at a spectral region of 0.9-1.5 μm with the direct absorption method

Koichi Iwata, Tomohisa Takaya, Hiro O. Hamaguchi, Akira Yamakata, Taka Aki Ishibashi, Hiroshi Onishi, Haruo Kuroda

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92 Citations (Scopus)

Abstract

Femtosecond time-resolved near-infrared spectra of TiO2 and Pt/TiO2 powders are measured at the wavelength region of 0.9-1.5 μm with the direct absorption method. Broad absorption bands of charge carriers, mainly free and trapped electrons, are observed for TiO2 and Pt/TiO2. The absorption band shape changes with a time constant of 160 fs after the photoirradiation, which most probably reflects the trapping of the generated free electrons. Population decay curves of the carriers after 1 ps, obtained for three different pump light powers, are well-explained by the second-order decay kinetics with a common second-order rate constant, indicating nongeminate recombination of the electron-hole pairs. When Pt is loaded to TiO2, an additional decaying process of 2.3 ps is observed. This decay component represents the transfer of generated electrons from TiO 2 to Pt, which is consistent with the known increase of overall catalytic activities by the Pt cocatalyst.

Original languageEnglish
Pages (from-to)20233-20239
Number of pages7
JournalJournal of Physical Chemistry B
Volume108
Issue number52
DOIs
Publication statusPublished - Dec 30 2004
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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