Effect of size and shape of nanocrystalline TiO 2 on photogenerated charges. An EPR study

Nada M. Dimitrijevic, Zoran V. Saponjic, Bryan M. Rabatic, Oleg G. Poluektov, Tijana Rajh

Research output: Contribution to journalArticlepeer-review

100 Scopus citations

Abstract

The continuous wave and pulsed electron paramagnetic resonance study of the photogenerated charges in differently shaped anatase nano-objects dispersed in aqueous solution is presented. Excitation of TiO 2 nanoobjects (spherical, faceted, rods, and bricks) at temperatures <80 K results in the formation of paramagnetic species that correspond to electrons trapped at lattice titanium within the bulk, (Ti 3+) latt, and holes trapped at oxygen atoms at the surface of nano-objects, as confirmed by the electron spin echo envelope modulation technique. The distortion of the Ti-O bond, which is a result of reconstruction of the surface of nano-objects, causes variations in g-tensor values and spin relaxation processes of lattice-trapped electrons. On the other hand, size and shape do not affect spin-spin relaxation times of surface-trapped holes as it was found that relaxation is determined by dipolar coupling with 1H nuclei from surrounding water.

Original languageEnglish (US)
Pages (from-to)14597-14601
Number of pages5
JournalJournal of Physical Chemistry C
Volume111
Issue number40
DOIs
StatePublished - Oct 11 2007
Externally publishedYes

ASJC Scopus subject areas

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

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