Characterization of TiO2 thin film photocatalyst prepared by rf-magnetron sputtering

摘要

TiO2 thin films as a photocatalyst have gained great attention due to their superior properties such as highchemical stability, non-toxicity as well as their applications in the development of environmentallyharmonious, sustainable, and energy-efficient technologies. Radio frequency (rf) magnetronsputtering have been one of the preferred methods for synthesizing TiO_2 thin films as it can produce ahighly uniform thin film, where the relation between sputtering conditions and structural, optical andmorphological properties of thin films were mostly focused. In the present study, using rf magnetronsputtering, we prepared TiO_2 thin films with different thickness on a quartz substrate by changing thedeposition time, and their optical, structural, and electronic properties were investigated by severalcharacterization techniques. Figure 1 shows the X-ray diffraction (XRD) and tauc’s plot of prepared thinfilms of different thickness by changing the deposition time from 1, 2 and 4 hours, respectively. Theanatase phase of TiO_2 in all the films was confirmed by XRD measurements. The crystalline size wascalculated to be about 50 nm in all films, which are enough large so that quantum size effect is negligible.With thicker films, optical bandgaps were found to increase from 3.22 to 3.36 eV. Photoluminescencestudies suggest that oxygen vacancy appears to be much more dominant in thick TiO_2 films. These oxygenvacancies are expected to be responsible for an optical band gap enlargement. Further, other properties suchas surface crystal structures and band structures will be discussed in the presentation. This work wassupported by JSPS KAKENHI Grant Numbers 17K05103, 18K14147.