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

doi:10.1021/jp0756395

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 journal › Article › peer-review

116 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 language	English (US)
Pages (from-to)	14597-14601
Number of pages	5
Journal	Journal of Physical Chemistry C
Volume	111
Issue number	40
DOIs	https://doi.org/10.1021/jp0756395
State	Published - Oct 11 2007
Externally published	Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Energy
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

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title = "Effect of size and shape of nanocrystalline TiO 2 on photogenerated charges. An EPR study",

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.",

author = "Dimitrijevic, {Nada M.} and Saponjic, {Zoran V.} and Rabatic, {Bryan M.} and Poluektov, {Oleg G.} and Tijana Rajh",

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T1 - Effect of size and shape of nanocrystalline TiO 2 on photogenerated charges. An EPR study

AU - Dimitrijevic, Nada M.

AU - Saponjic, Zoran V.

AU - Rabatic, Bryan M.

AU - Poluektov, Oleg G.

AU - Rajh, Tijana

PY - 2007/10/11

Y1 - 2007/10/11

N2 - 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.

AB - 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.

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

Abstract

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