Effect of size and shape of nanocrystalline TiO2 on photogenerated charges.: An EPR study

被引：106

作者：

Dimitrijevic, Nada M. ^{[1
]}

Saponjic, Zoran V. ^{[1
]}

Rabatic, Bryan M. ^{[1
]}

Poluektov, Oleg G. ^{[1
]}

Rajh, Tijana ^{[1
]}

机构：

[1] Argonne Natl Lab, Ctr Nanoscale Mat, Chem Div, Argonne, IL 60439 USA

来源：

JOURNAL OF PHYSICAL CHEMISTRY C | 2007年 / 111卷 / 40期

关键词：

D O I：

10.1021/jp0756395

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

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 TiO2 nano-objects (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, (Ti3+)(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 H-1 nuclei from surrounding water.

引用

页码：14597 / 14601

页数：5