Enhancement of photoelectric and photocatalytic activities: Mo doped TiO2 thin films deposited by sputtering

TiO2 thin films doped with different contents of Mo were deposited by DC reactive magnetron sputtering. Surface morphology, crystal structure, elements' valence states and absorption edge of each sample were characterized by atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet–visible spectrometer. Cyclic voltammetry was utilized to study the photoelectric properties while the photocatalytic activity was evaluated by the degradation rate of methylene blue. The result indicates that an appropriate concentration of Mo could extend the absorption edge of TiO2 film to visible range remarkably. When the content reached 0.9 at.%, with a xenon lamp we observed the strongest photocurrent as well as the best photocatalytic property while under the illumination of strong visible light, a photocurrent 10 times the undoped sample appeared. The electrochemical impedance spectroscopy observed the fastest speed of carrier transfer as doping content increased to 0.9 at.%, while higher doping amount would precipitate carrier recombination due to a large number of lattice defects.

► Mo-doped TiO2 thin films were deposited by DC reactive magnetron sputtering.
► Doped films present high specific area and well-grown crystals.
► Proper content of Mo accelerates charge separation and inhibits the recombination.
► Enhanced photocatalytic activity under ultraviolet light is attained by doping.
► Under visible light, the strongest photocurrent after doping increases tenfold!