Research On The Preparation And The Photocatalytic Activity Of Doped Tio₂

Conventional TiO₂ as a photocatalytic material, with attractive characteristics of long-term stability and nontoxicity, has been widely studied in the past years. However, TiO₂ with its absorption edge below 380nm has photoactivity only under ultraviolet (UV) light. Thus, only a small portion of the solar energy can be utilized, which increases its placation cost seriously. This is the main reason why TiO₂ has not been widely used in practice. How to effectively utilize sunlight as the light Source is one of the important subjects for the wide application of TiO₂. In recent years, theoretical and experimental studies have indicated that some doped TiO₂ can greatly enhance the photoactivity compared with pure TiO₂ in the visible spectral range. Hence, great effort has been made for the doped TiO₂. Now, many researchers are searching for ideal photoactivity materials about doped TiO₂.This article tells the preparation of doped nano-TiO₂ using sol-gel method, the property especially photoactivity of the samples. We selected the element N and V to prepare doped TiO₂, including powder and film. The samples are pure TiO₂, N-doped TiO₂, V-doped TiO₂, and N-F-co-doped TiO₂. Most instruments for testing are laser particle characterization system, XRD, and UV-Vis.By testing the doped TiO₂ samples, wo found that both N-doped TiO₂ and V-doped TiO₂ can enhance the photoactivity compared with pure TiO₂ in the visible spectral range. The optimum doping concentration of nitrogen and vanadium were 3% and 1%, The optimum calcination temperature was 400℃. However, among all the samples, N-F-co-doped TiO₂ has the most visible-light photoactivity and the most obvious red-shift, which had been calcined for two hours at 400℃. The concentrationg of nitrogen and vanadium were 3% and 1% in this N-F-co-doped TiO₂. Using a sewage degradation system assembling by ourselves, we chose two kinds of samples to comparative study their photocatalytic activities in visible-light. Meanwhile, we use porous nickel foam as catalyst carriers. One of the photocatalyst was N-doped TiO₂ with 3% nitrogen doping, the other was N-F-co-doped TiO₂ with 3% nitrogen doping and 1% vanadium doping. We planted this two photocatalysts on porous nickel foam using sol-soaked method and then calcined for two hours at 400℃. The result of degradation of Methyl Orange solution shows us: the photocatalysts either N-doped TiO₂ or N-F-co-doped TiO₂ can successfully degrade the Methyl orange solution, but the N-F-co-doped TiO₂ photocatalyst were obviously more efficient.