Photocatalytic activity of TiO2 films with mixed anatase and rutile structures prepared by pulsed laser deposition

Transparent TiO2 films with typical anatase structure were prepared by pulsed laser ablated titanium (99.99%) target onto quartz glass substrates at 700 °C in oxygen pressure of 10 Pa. The as-deposited films were then annealed at 800 °C in an oxygen atmosphere for different time to produce films with mixed anatase and rutile structures. The titanium dioxide (TiO2) films with mixed anatase and rutile structures show higher photocatalytic efficiency than the film with only anatase structure. The highest visible-light photocatalytic efficiency of 64% was observed from the film with 33% rutile phase. TiO2 films with mixed structures exhibit lower band energy. The high photocatalytic efficiency of the films with mixed structures was explained by the increasing excitation in visible-light region and the restraining of the recombination of electrons and holes, which increase the absorption of the surface organic or inorganic species during the photocatalytic process.