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
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
收藏
页码:14597 / 14601
页数:5
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