Low Temperature Synthesis of Mixed Phase Titania Nanoparticles with High Yield, its Mechanism and Enhanced Photoactivity

A novel process was developed for the synthesis of a mixed phase (constituted of 66% anatase phase) of TiO2 nanoparticles at lower calcination temperature (400 degrees C) by the sol gel technique using a cost effective and easily available propanol solvent. Stereochemistry of propanol played a crucial role towards crystallographic phase of resultant TiO2 nanoparticles where n-propanol gave mixed phase while i-propanol gave pure anatase. A plausible mechanism has been proposed. An effect of crystallographic phase on their photocatalytic activity was studied using degradation of bromophenol blue dye. The rate constants of the dye degradation reaction for anatase phase and mixed phase were found to be 6.86 x 10(-3)/s and 1.56 x 10(-2)/s respectively. A mixed phase of TiO2 showed faster (120 min for 84%) photodegradation compared to the anatase phase (270 min. for 84%) due to an effect of crystalline and electronic parameters. The cyclic voltammetry results depicted the reducing nature of i-TiO2 than n-TiO2, which creates unfavorable situation for the electron transfer from TiO2 to dye.