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.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films