| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF-ThP |
| Session: | Thin Film Poster Session |
| Presenter: | Taishi Segawa, Kogakuin University, Japan |
| Authors: | T. Segawa, Kogakuin University, Japan I. Takano, Kogakuin University, Japan |
| Correspondent: | Click to Email |
In recent years, titanium oxide (TiO2) has been attracting attention by its various properties and has been studied in a wide field such as application to solar cells or medical instruments. One of the reasons why TiO2 is the superior material as a photocatalyst is that the photo-excited state is very stable and does not cause autolysis. Therefore TiO2 irradiated with ultraviolet rays can make the electrolysis of water stably proceed. On the other hand, the inferior point of TiO2 is that the absorption wavelength is limited to the ultraviolet region under 380 nm. Therefore, many researchers have studied to improve the efficiency of the light reaction of TiO2. The distinctive point of our study is the energy supply of electricity with the light irradiation. In this report, the optimum conditions of each film thickness and applied voltage were examined.
In this study, the glass substrates of 15 × 9 mm cleaned by an ultrasonic cleaner with acetone for 5 minutes were used. The TiO2/Ni thin films were prepared by the multi-process coating apparatus with magnetron sputtering sources. The TiO2 thin film preparation was carried out by sputtering a Ti target introducing an Ar and an O2 gas. An Ar gas and an O2 gas flow rate were set to 1.5 sccm and 20 sccm, respectively. The glass substrates were heated to 200 degrees by an infrared heater. The film thicknesses of TiO2 were changed with 0 - 200 nm and Ni were changed with 25 - 100 nm to investigate the suitable condition.
The crystal structure of each thin film was analyzed by X-ray diffraction. Optical properties were measured using a UV-Visible spectrophotometer. The photocatalytic properties were measured by a methylene-blue immersion test under irradiation of the artificial sunlamp (visible light) for 2 hours. The change of the methylene-blue transmittance was measured using a UV-Visible spectrophotometer.
In this study the change of the methylene-blue transmittance was regarded as the effect of photocatalytic characteristics. The transmittance of a voltage application showed 8 times from 4 times as compared with the case of an unapplied voltage. The transmittance of a methylene-blue solution for the TiO2/Ni (200/100) thin film showed the highest value of 48 % by a voltage application. On the other hand, the applied voltage dependence of the TiO2/Ni (200/100) thin film showed the highest value at 2.0 V in an applied voltage. Over 2.0 V of an applied voltage, the transmittance of a methylene-blue solution gradually decreased. It was considered that the recombination of electrons and holes was delayed by applying a voltage of an appropriate value.