Visible Light Driven New Photocatalyst Taon Of The Preparation And Performance

It has been the important issues using the semiconductor photochemical catalysis oxidation technology to eliminate pollution of the environment in the field. TiO₂ has been studied widely because of its higher photocatalytic activity, higher stability, nontoxicity and low-cost. However, TiO₂ may show photocatalytic activity only by irradiation of ultra violet(UV)light for its wide band gap(Eg=3.2 eV). Meanwhile, the ultraviolet ray (λ<400 nm) account for less than 5% in the solar spectrum, the majority is the visible light for the wave length is 400～750 nm. So This makes the technology is limited. It is vital for study on photocatalyst with the highest photocatalytic activity by visible-light in order to apply sun-light effectively.TaON as a new photocatalysts with higher absorbency in visible area has been synthesized with Ta2O5 and NH3 as the raw material. Furthermore, M/ TaON was prepared by loading M on the surface of TaON by photoreduction method(M=Pt,Rh,Ru). In addition, XRD, XPS, and UV-VIS analysis are made for prepared photocatalysts. Test results showed that the reaction temperature, time, and the flux of ammonia gas is a catalyst structure and composition of important factors. The result of the analysis shows that the XRD pattern of the prepared sample, which is prepared when the reaction temperature is 850℃, the reaction time is 10 hours and the flux of ammonia gas is 100 mL/min, is the same as that of TaON. Thus the most optimal technical parameter of synthesizing the catalyst has been determined. Non-stoichiometric sample, TaO_1.3N_0.8, is formed under the above reaction condition.In order to investigate the responding area to the light, UV-VIS analysis has been made for the sample which has been synthesized under the most optimal reaction condition. The result indicates that the responding area to the light has been widened to 500 nm, proving that the prepared TaON shows the responding ability to the visible-light.Furthermore, the photocatalytic activities of TaON for degradation of dichloroactic acid (DCAA) under irradiation of visible light are also investigated in the paper. The effects of preparation condition of TaON photocatalyst, category and loading amount of noble metal as well as amount of photocatalyst, reaction time on the rate of DCAA degradation are studied by analyzing the concentration of Cl- with Ion Chromatography. The result shows that TaON can decompose DCAA under irradiation of visible light. The maximal degradation rate is 33.65% during 120 minutes reaction with adding 20mg photocatalyst in 100 mL solution .The noble metal can increase photocatalytic activities. While loading amount of Pt was 1.5wt%. The degradation rate of DCAA was 1.52 times as without noble metal after irradiation for 120min under visible-light.Finally, the reaction mechanism and dynamics of photodegradation with prepared photocatalyst by degradation of DCAA is studied on the base of the experimental results. The investigation on dynamics of photocatalytic degradation for DCAA by TaON shows that it is in agreement with one order dynamics model.