Preparation And Characterization Of Fe-doped Titanium Dioxide Thin Films With Micro/Nano Structures

With the advantage of high photocatalytic activity, no toxicity and low cost, TiO2photocatalyst has broad prospects in hydrogen generator, solar energy conversion and storage, degradation of harmful organic pollutants and air purification, etc. However, TiO2could only be activated by shorter wavelength UV light because of its large band gap, while the UV light energy part in the solar spectrum is only about4%(visible light energy accounts for about43%), which limits the photocatalytic property and application of TiO2to a large extent. Therefore, narrowing the band gap of TiO2, expanding the scope of its response to the visible zone, and improving the utilization of solar energy is the research hot points in recent years.Doped properly with other elements is an effective means to make TiO2with visible light photocatalytic activity. In this paper low-temperature oxidation of titanium foils in hydrogen peroxide solutions and anodic oxidation were used to prepare Fe-doped TiO2thin films, respectively. The components, structures and photo-absorption properties of Fe-doped TiO2thin films were charactered by SEM, EDS, XRD, XPS and UV-Vis absorption spectroscopy. The exact work is as following:(1) The mixed powders with different proportions of Ti powder and Fe powder were put into the30%hydrogen peroxide solutions, and then Ti foils were soaked into the solutions with the temperature kept at80℃for72h. The Fe-doped TiO2thin films were deposited on Ti foils. It turned out that loose Fe-doped anatase TiO2thin films were formed on Ti foils. Fe-doped TiO2thin films with different Fe contents all indicated red-shifted absorption features and the band gaps all reduced compared with the undoped TiO2thin films. The band gap of the3%Fe-doped TiO2thin films decreased to3.04eV.(2) Anatase Fe-doped TiO2film with nanorod structure was fabricaed by anodization of Ti foil in the1%HF/0.5M Fe(NO3)3electrolyte at voltage30V for30min. The band gap of the Fe-doped TiO2film is3.02eV and obvious shift of absorption edge to long wavelength was observed.(3) Anatase Fe-doped TiO2film with nanotube arrays was fabricaed by anodization of Ti foil in the0.5%HF/0.5M Fe(NO3)3electrolyte at voltage20V for20min. The band gap of the Fe-doped TiO2nanotubes is3.18eV and the red-shift of absorption edge was also observed.(4) Fe-doped TiO2film with nanotube arrays was formed by anodization of Ti-Fe alloy in the0.5%HF electrolyte at voltage20V for20min. XRD results show that the nanotubes consist of rutile/anatase TiO2mixed crystals.