Preparation And Photocatalytic Activity Of TiO₂-FeOOH Nanocomposite By Molecular Self-assembly Method

Photocatalytic oxidation process is a kind of advanced oxidation technology and it has a great application potential in environmental pollution control with the characteristics of high efficiency, low energy consumption, and the oxidizability of most organic compounds, especially non-biodegradable organic contaminants. TiO2(titania) is one of the most efficient semiconductors currently available for the photocatalytic degradation of organic contaminants. However, it should be noted that the disadvantages including narrow spectral response, low quantum efficiency, coagulation of nano-powders, and difficulty in recycle have restricted its application. In order to solve the above problem, this study has proposed to prepare nano-FeOOH films using self-assembled method based on environmental mineralogy, and then composite with nano-TiO2, in order to change the level structure of TiO2 and FeOOH to improve the photocatalytic performance. The main research work are as follows:? Studied the factors such as anionic species, cation concentration, pH value, water bath temperature,water bath time, and semiconductor layer sequence affecting the nano composites, and determined the optimize preparation conditions of nano TiO2-FeOOH composites by using orthogonal test.? FT-IR, XRD, SEM, TEM were used to characterize the micro-structure of composites. XRD and TEM show that the samples are assembled by anatase and goethite, the size of anatase was 5-10 nm, and goethite was a little bigger than anatase. The change of anionic species in the preparation of FeOOH has no effect of construction of composites. SEM images show that the samples are constitute by a lot of nano flower structure which is 200~300nm, the size of petal was range from a few nanometers to 20 nm, and that this structure is benefitial to the enhancement of adsorptive property and thus to the improvement of the performance of photocatalysis. The growth pattern of TiO2/FeOOH nanocomposite was "skeleton" structural pattern which had a greater stability, and the growth pattern of FeOOH/TiO2 was "inlay insert" mode.? Studied the influence of the form, construction and photocatalysis performance of Ti O2-FeOOH composites in different semiconductor complex sequence. Results indicate that the change of semiconductor complex sequence has no effect on the form and construction of nano-composites. The composite of TiO2 and FeOOH was beneficial to the decrease of band gap, but the enhance of photocatalytic activity was also relative to the sequence of semiconductor, but the composite whose outer layer was TiO2 had better carrier separation effect than the composite whose outer layer was FeOOH, so that TiO2/FeOOH had a better photocatalytic activity than FeOOH/TiO2 under natural light.? Selected the quartz glass and activated carbon as substrate materials of the composites,studied the influence of the form,construction and photocatalysis performance of TiO2-FeOOH composites in different substrate materials. Results indicate that the difference of substrate materials has no effect on the form and construction of nano-composites, but it has influence on the micro structure or pole structure and adsorptive property of nano-composites, so that it has influence of photocatalysis property. Because of the synergy effect between surface adsorption and photocatalysis, photocatalyst which has stronger adsorbability has a better photocatytic activity.