Improving optical and charge separation properties of nanocrystalline TiO2 by surface modification with vitamin C

T. Rajh, J. M. Nedeljkovic, L. X. Chen, O. Poluektov, M. C. Thurnauer

Research output: Contribution to journalReview articlepeer-review

325 Scopus citations


The structural and electrochemical properties of nanoparticles were found to be different from those of the corresponding bulk semiconductors. Due to the specific binding of modifiers to "corner defects", the optical properties of small titania particles were red shifted 1.6 eV compared to unmodified nanocrystallites. It was found using electron paramagnetic resonance (EPR) that, as with organic charge transfer superconductors, these novel nanocrystallites operate with a charge-transfer mechanism, and exhibit semiconducting properties through both constituents (large band gap semiconductor and organic modifier). The EPR spectra were consistent with hole trapping on the surface modifier and electron trapping on shallow interstitial and partially delocalized Ti sites. These systems have an important feature in that charge pairs are instantaneously separated into two phases-the holes on the donating organic modifier and the electrons in the conduction band of TiO2.

Original languageEnglish (US)
Pages (from-to)3515-3519
Number of pages5
JournalJournal of Physical Chemistry B
Issue number18
StatePublished - May 6 1999
Externally publishedYes

ASJC Scopus subject areas

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


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