Efficient luminescence and photocatalytic behaviour in ultrafine TiO2 particles synthesized by arrested precipitation

We have demonstrated optical and photophysical properties of newly synthesized ultrasmall TiO2 nanoparticles. The particles are synthesized by arrested precipitation method in trioctylphosphine oxide (TOPO) and benzophenone as the capping agent and also as solvent at high temperature in Ar atmosphere. High-resolution TEM and XRD measurements revealed that the particles are in the size range of 3.3-3.5 nm. Optical absorption spectra of these particles show large blue shift indicating a quantum confinement effect. The particles are highly luminescent, which is very unusual for an indirect band gap material. The emission quantum yield has been measured to be >2%. Again the photocatalytic activity of newly synthesized TiO2 particles was found to be much higher as compared to TiO2 nanoparticles, indicating a better photocatalytic material arising due to size quantization.