Degradation of environmental hormone by visible light active double layer photocatalyst

点击翻译按钮获取中文摘要

We have prepared photocatalytic TiO_2 films by reactive DC sputtering from Ti pure metal and mixture gas of Ar+O_2. The degradation of water solution containing 17β-estradiol well known as female sex environmental hormone was performed under irradiation of UV light to the surface of TiO_2 film set up in the water solution. The concentrations of 17β-estradiol in the water solution were estimated from the measurement of HPLC in intervals during UV light was turned on. At initial stage, the degradation rate was faster with increasing UV light intensity After irradiation period was six hours, the degradation rate was saturated and independent of UV light intensity The degradation rate was different in the films deposited at different sputtering pressure. This may be due to the difference of surface area and porosity in the films.To enhance the photocatalytic activity to visible light in solar light, we have prepared the double-layered photocatalyst composed of TiO_2 and WO_3 films. First, the WO_3 films were deposited on glass substrates by reactive sputtering. We annealed the as-deposited WO_3 films to improve the crystallinity, optical properties and surface microstructure. Then, TiO_2 films were deposited on the annealed WO_3 films by reactive sputtering. The 17β-estradiol was decomposed by the double-layered photocatalyst under irradiation of artificial solar light to the surface of TiO_2 film. The concentrations of 17β-estradiol were also estimated from HPLC, during the artificial solar light was turned on. When six hours passed after the light was turned on, the degradation rates of 17β-estradiol water solution were obtained as a values of 45% for single-layered TiO_2 films, and 57% for the double-layered photocatalyst, respectively.These results suggest that WO_3 under layer in double-layered photocatalyst could be effectively activated for visible light and assist with the enhancement of photocatalytic activity of TiO_2 upper layer.