Structure, wettability and photocatalytic activity of CO2 laser sintered TiO2/multi-walled carbon nanotube coatings

Nanocomposites of titanium dioxide (TiO(2)) and multi-walled carbon nanotubes (MWNTs) were prepared and deposited by sol-gel spin coating on borosilicate substrates and sintered in air at 300 degrees C for 15 min. Further irradiation of the films with different CO(2) laser intensities (4.3-17 W m(-2)) was carried out in order to crystallize TiO(2) in the anatase form while preserving the MWNT's structure. The laser irradiation changed the crystal structure of the coatings and also affected the wettability and photocatalytic activity of the films. The anatase phase was only observed when a minimum laser intensity of 12.5 W m(-2) was used. The contact angle decreased with the enhancement of the laser intensity. The photocatalytic activity of the films was determined from the degradation of a stearic acid layer deposited on the films. It was observed that the addition of carbon nanotubes themselves increases the photocatalytic activity of TiO(2) films. This efficiency is even improved when high CO(2) laser intensities are used during the sintering of the coatings.