Ion-assisted electron-beam evaporation of carbon-doped titanium oxide films as visible-light photocatalyst

Carbon-doped titanium oxide films (TiOxCy) were deposited by an ion-assisted electron-beam evaporation system, using rutile TiO2 powder as the source material and carbon monoxide flowing through an ion gun as the dopant source. A series of films was prepared under the bombardment of ion beam with a fixed voltage of 1000 V and various beam currents of 10, 20 and 35 mA. As-deposited films have the primary structure of anatase TiO2, characterized by X-ray diffraction and Raman spectroscopy. With the increasing ion-beam current, the film crystallinity deteriorated, the concentration of carbon with Ti–C bonding in the films varied from 0.8 to 1.3 mol%, and their optical absorption edges gradually red-shifted from 370 to 410 nm. The TiOxCy film deposited with 10 mA beam current has well-crystallized anatase phase, exhibiting the highest water-contact angle reduction and the best visible-light photocatalytic activity.