Effect of Calcination Temperature and Environment on Photocatalytic and Mechanical Properties of Ultrathin Sol-Gel Titanium Dioxide Films

Effects of calcination environment (air and nitrogen) and temperature (400 degrees-1000 degrees C) on the structure, optical, photocatalytic, and mechanical properties of ultrathin sol-gel titanium dioxide (TiO2) films were studied. X-ray diffraction and Raman analysis of the films have shown preferred rutile formation at high calcination temperatures and low oxygen pressures. Films calcined under nitrogen flow were optically absorbing and contained significant amounts of carbon due to the carbonization of the organic precursor, which also resulted in a porous structure. Although photocatalytic activity of the films calcined in different atmospheres showed similar temperature dependencies, nitrogen-calcined films performed better at high calcination temperatures and showed improved visible light activity. On the other hand, the mechanical properties of films calcined in air were superior to those calcined under nitrogen.