Study On Preparation And Photocatalytic Activity Of Iron-doped Nano-TiO2 Thin Films Based On Self-assemble Mololayers (SAMs)

Appeared in the late 80's in 20th century,nano-TiO2 has been paid more and more attention in the fields of water treatment,sterilization and environmental protection because of its unique optical and electronic properties.Otherwise, as photocatalytic materials, TiO2 has its own defects,such as its low utilization of solar.So that the photocatalytic properties is affected. To enhance the photocatalytic activity of TiO2 and make effective use of sun light,the sorts of modified methods have been studied.Two-dimensional iron-doped nano-TiO2 thin films were synthesized from aqueous system at low-temperature by this paper with TiCl4 as Ti resource, SAMs(self-assembled monolayers) as template and Fe(NO3)3-9H2O as adulterant.The photocatalytic activity was evaluated by the degradation of methyl orange solution under UV and visible light radiation, also by the degradation of benzene in gas phase systerm under UV radiation. And discussed the influence of iron on the photocatalytic activity of TiO2.The main conclusions of this study are shown as follows:1) With Fe(NO3)3·9H2O as adulterant, a series of Fe3+-TiO2 nano-films maily containing rutile were synthesized from TiCl4 solutions on quartz glass (100*20*3mm) at water bath temperature 80℃for 4h, adopting the self-assembled monolayers (SAMs) contained outside functional group-SH as template. To change reaction conditions(stirring), the content of rutile and anatase in sample could be controlled.2) Using Fe3+-doped TiO2 as photocatalysts to treat methyl orange (MO) solutions under visible light and UV radiation, we can see:Fe3+-doped TiO2 had optimum activity when Fe3+ adsorption amount was 0.5mmol/L, under UV for 4h and visible light radiation for 6h, the degradation datas of MO were respectively 98.62% and 87.21% and enhanced respectively by 63% and 31% than that of pure TiO2.3) The degradation performances of samples with different content of rutile and anatase on the methyl orange were comparied.For different photocatalysts of series,the degradation datas of MO under visible light were respectively 87.21% and 90.24%.4) To ensure photocatalytic performance, the treated MO mystic was analysised by FTIR.The results of FTIR showed that almost azo linkage and benzene ring of MO were opened.5)TiO2 and 0.5mmol/L doped Fe3+-doped TiO2 films were used as photocatalysts to degradate beneze into CO2. Fe3+-doped TiO2 films showed higher photocatalytic activity of benzene degradation than that of pure TiO2. After 80min, the increment of CO2 and the relative concentration of beneze were respectively 229.368 and 0.6749, which respectively increased by 34% and decreased by 8.4% than that of pure TiO2 film. The doped iron obviously improved photocatalytic activity of TiO2.6) Dynamic analysis and the degradation progress of MO and beneze were studied, and the results indicated that the process of photodegradation followed the first order reaction kinetics model.