Influence of laser modification of TiO2 films for its photocatalytic properties

The photocatalytic activity of TiO 2 layer modified by laser radiation is discussed in the paper. Commercially available nanopowder P25(Degussa) was used, which consists of a mixture of anatase and rutile - two crystallographic forms of TiO 2 . The spin-coating technique was applied to produce thin layers on glass. After drying and calcination the layer was thermally modified using a pulsed (6 ns) Nd:YAG laser (FHG 266 nm). This caused a clearly visible surface darkening effect. The XRD spectra show that phase change transition (from anatase to rutile) took place partially. This was also confirmed by Raman spectra. The main peak of Raman-spectra shifts from 142,84 to 145,22 cm -1 , probably due to decreasing size of TiO 2 nanoparticles or more probably due to a defects generation in nanocrystallite structure. Defects have been reported in the literature as surface oxygen depletion and generation valance states Ti 3+ and Ti 4+ . Eventually, kinetics of methylene-blue decay and CO 2 to methane conversion were examined. In both cases an increase of catalytic activity was observed.