Photocatalytic Characteristics of TiO2 Thin Films Prepared by Dc Reactive Magnetron Sputtering with added H2O

Abstract

A high-performance photocatalytic TiO2 thin film was successfully obtained by dc reactive magnetron sputtering with added H2O. The film was deposited onto SiO2-coated glass at a substrate temperature of 300°C using a titanium metal target in a combined Ar, O2 and H2O atmosphere. Photocatalytic performance was evaluated by measuring the change in concentration of methylene blue (MB) under UV irradiation. The photocatalytic performance of the film increased as the quantity of added H2O increased: when 70 sccm of H2O was added, the decomposition capability was about 1.6 times greater than a reference sample (sol–gel-derived TiO2 thin film). The film was characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), UV-VIS-NIR spectrophotometry, attenuated total reflection Fourier transform infrared spectrometry (ATR-FTIR), and photoluminescence spectrometry. Included in the film were a large number of OH groups. The surface morphology of the film had a domain structure, with each domain consisting of many sputter grains with the same orientation. The number of oxygen vacancies level in the forbidden band decreased as the quantity of H2O added during deposition increased. In addition, the Ti–OH dependent peak intensity increased when H2O was added. It was observed that this process would enable us to hydrogenate TiO2 more easily and thereby improve photocatalytic performance.