Enhanced Photocatalytic Activity of TiO2 Thin Film Deposited by Reactive RF Sputtering under Oxygen-Rich Conditions.

TiO₂ thin films are promising as photocatalysts to decompose organic compounds. In this study, TiO₂ thin films were deposited by reactive radio-frequency (RF) magnetron sputtering under various flow rates of oxygen and argon gas. The results show that the photocatalytic activity decreases as the oxygen-gas ratio is increased to 30% or less, while the activity increases under oxygen-rich conditions. It was observed that the crystal structure changed from anatase to a composite of anatase and rutile, where the oxygen-gas ratio during RF sputtering is more than 40%. Interestingly, the oxygen vacancy concentration increased under oxygen-rich conditions, where the oxygen-gas ratio is more than 40%. The sample prepared under the most enriched oxygen condition, 70%, among our experiments exhibited the highest concentration of oxygen vacancy and the highest photocatalytic activity. Both the oxygen vacancies and the composite of anatase and rutile structure in the TiO₂ films deposited under oxygen-rich conditions are considered responsible for the enhanced photocatalysis. [ABSTRACT FROM AUTHOR]