The Study On Photocatalytic Properties Of Amorphous TiO₂-Ag (Mo) Thin Films Deposited By Magnetron Sputtering

Titanium dioxide has received wide attention due to its high stability, great catalytic activity and potential application in solving environmental problems. Pure TiO₂, however, demonstrates a low photocatalytic activity because of its wide band-gap (Eg=3.2eV), low utilization of solar energy and high compounding between electrons and holes of photochemical reactions. Therefore, many researchers pay attention to doping other chemical elements or making compound of titanium oxide semi-conductor thin film as the valid way that improves its photocatalytic properties.The previous modification studies were based on the crystalline TiO₂ films, but little attention has been paid to the amorphous TiO₂ films due to lack of photocatalytic activity [1]. In this paper, the amorphous TiO₂-Ag films and TiO₂-Mo films were prepared by reactive magnetron sputtering at room temperature, so as to explore the photocatalytic activity of amorphous TiO₂ films deposited by different elements.In this paper, the argentum-doped titanium oxide thin films were deposited on slides by magnetron sputtering. Ag-doping sputtering mode, Ag-doping sputtering power and the influence of O2 flow on the photocatalytic activity of TiO₂-Ag films is investigated. The experiment results showed that when Ag-doping sputtering mode is"Front 10min", the rate of photodegrading methylene blue is 72%; when Ag-doping sputtering power is 30W, the rate of photodegrading methylene blue is 95%; when O2 flow is 40SCCM, the rate of photodegrading methylene blue is 94%. The crystalline structure, electronic structure and thickness of the films were analyzed and tested by XRD, STS and Ellipsometric instrument. The result of XRD showed that TiO₂-Ag films are amorphous. The STS spectra showed that the prepared film possesses a band gap of 1.8eV, the narrow band-gap is the primary reason why amorphous TiO₂-Ag film has photocatalytic activity. The result of photodegrading methylene blue whose concentration is 10mg/L showed that as the thickness of the film increases, the rate of photodegradation rises. When the thickness of the film is 360nm, the rate of photodegradation is 90% in 2 hours, and when the thickness is over 360nm, the rate of photodegradation doesn't increase. The result of photodegrading rhodamine B whose concentration is 2mg/L showed that as the thickness of the film increases, the rate of photodegradation rises a little, and it is 88.7% in 3 hours. TiO₂-Mo films are also prepared and its process parameters are discussed. Moreover, the result of XRD showed that TiO₂-Mo films are amorphous. The result of photodegrading analysis showed the amorphous TiO₂-Mo films have certain photocatalytic effect on methylene blue, but the primary reason of photodegrading methylene blue is adsorption of TiO₂-Mo films and is explained by measurement of contact angle.