Effect of temperature on the physical, optical and photocatalytic properties of TiO2 nanoparticles

In this paper we describe the effect of calcination temperature on the structural, morphological, optical and photocatalytic properties of TiO2 nanoparticles. The titanium dioxide powders were produced by the sol-gel method starting from titanium tetraisopropoxide (TTIP) in neutral aqueous medium (pH 5.5). After that, the TiO2 nanoparticles were treated at three different calcination temperatures for 4 h: 100, 450 and 800 degrees C. Then, the powders were characterized by XRD, Raman and photoluminescence techniques. We observed the anatase phase for the powders treated at 100 and 450 degrees C and rutile for that treated at 800 degrees C. The photocatalytic activity of the TiO2 powders was investigated using Methylene Blue test and showed a strong correlation with the temperature (i.e. TiO2 phase). The better photocatalysis exhibited by the nanoparticles treated at 100 and 450 degrees C compared to the powder at 800 degrees C was due to the higher recombination of photo-generated electrons and holes of rutile with respect to anatase.