Recombination pathways in the degussa P25 formulation of TiO 2: Surface versus lattice mechanisms

Deanna C. Hurum, Kimberly A Gray*, Tyana Rajh, Marion C. Thurnauer

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

371 Scopus citations


Charge migration between electron trapping sites within the mixed-phase titania photocatalyst Degussa P25 has been studied. In addition to previously described lattice electron trapping sites on both anatase and rutile phases, surface electron trapping sites and an anatase-rutile interface trapping site specific to Degussa P25 are identified. The relationship between these sites and recombination with surface hole trapping sites is also determined. It is experimentally shown that upon band-gap illumination holes appear at the surface and preferentially recombine with electrons in surface trapping sites. These findings indicate that in mixed-phase TiO 2, such as Degussa P25, photogenerated holes are trapped exclusively on the particle surface, while photogenerated electrons are trapped within the nanoparticle lattice. Recombination reactions are dominated by surface reactions that follow charge migration. These findings indicate that, in mixed-phase TiO 2, such as Degussa P25, a random flight mechanism of recombination predominates. Such knowledge simplifies the mechanistic mathematical models used for process design and points the way for improving future oxidative titania catalysts.

Original languageEnglish (US)
Pages (from-to)977-980
Number of pages4
JournalJournal of Physical Chemistry B
Issue number2
StatePublished - Jan 20 2005

ASJC Scopus subject areas

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


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