Optical and Photochemical Properties of Sodium Dodecylbenzenesulfonate (DBS)-Capped TiO2 Nanoparticles Dispersed in Nonaqueous Solvents

TiO 2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) have been synthesized so that they can be dispersed in many organic and nonaqueous solvents. It has been found that DBS-capped TiO 2 nanoparticles have a significant red shift of the optical absorption band edge and clear photoluminescence at room temperature in contrast to that of bare TiO 2 nanoparticles. The results obtained indicate that the surface structure, that is, the capping group and the defect states, plays an important role in the electronic states of TiO 2 nanoparticles. The recombination dynamics of the photoexcited charge carriers (electron and hole pairs) of DBS-capped TiO 2 as studied by picosecond transient absorption spectroscopy is found to be much slower as compared to that of bare TiO 2 nanoparticles as reported earlier.