¦¡-fe <sub> 2 </ Sub> O <sub> 3 </ Sub> Of Tio <sub> 2 </ Sub>, Zno Composite Nanomaterials And Photocatalysis Research

Recently ,with the excessive exploitation of natural resources and serious pollution of environment, the deterioration of mankind living environment has become more and more serious. Photocatalystic process is a kind of photodecomposition reaction by the reaction between the harmful pollutants and electron-hole pairs generated by the semiconductors from its conduction band and valence band respectly while absorbing phonons. Comparing to the other techniques, photocatalystic process have these excellencies below: no more secondary disposal, decompose the organic pollutants into H₂O, CO₂ and some other small molecular, mineralize the inorganic pollutants, can be reused.An ideal photocatalyst should be stable, inexpensive, non-toxic, and highly photoactive and with a good visible light absorption spectra. The preparation of photocatalysts with high photocatalytic efficiency is most important in photocatalysic technology. However, there are still some problems with the as studied photocatalyst, such as narrow light absoption spectra, high electron-hole compositing rate and low photocatalystic efficiency,etc. So, the main point of the photocatalystic research in the future is to extend the photo responding spectra, increase the efficiency of charge separation and improve the efficiency of the photocatalyst.TiO₂ is one of the most popular photocatalystic materials now, which has been widely studied and used, with high stability, relatively high efficiency and non-toxic properties. However, its band gap is wide (about 3.2ev) with a absorption peak at 387.6nm. It can only absorb UV irradiation which is only a small fraction of the whole solar spectra, and additionally, it also possess a high electron-hole compositing rate, which lead to a low photocatalystic efficiency. ZnO is another popular semiconductor with superior photoelectronic properties. And the main point was focused on the photolumiminescence and dielectrical properties now. Little research has been done about its photocatalysitic properties. ZnO has some better properties than TiO₂, though it has a similar band gap structures (3.37ev) with TiO₂. α-Fe₂O₃ is a semiconductor with a band gap of 1.9-2.2eV.It has a good absorbing spectrum according with the solar spectrum. But the efficiency of absorbing is so low. According to the advantages and disadvantages , if we can make α-Fe₂O₃and TiO₂, ZnO together effectively and form the core-shell structure then it will has potential application and practical value. Therefore, through composition of semiconductor ,we hope to improve the efficiency of photocatalysts, extend the photo-responsing range, and increase the efficiency of charge separation.Materials of α-Fe₂O₃, α-Fe₂O₃/TiO₂ and α-Fe₂O₃/ZnO core/shell structure were obtained by hydrothermal method, then the properties were also studied in-depth . The following is the content of this paper and the result we get.1) In chapter 1 we introduce the context of photocatalysts, the type and principle of photocatalytic reaction , method of preparation , appliance and changing quality of photocatalysts. On the base of summarizing photocatalystic field, We indicate problem of research and goal of anticipation on the paper2) In chapter 2 the different appearance of α-Fe₂O₃ was formed by hydrothermal method. They were marked by XRD, TEM, SEM etc.. Nanoparticles were formed like nanorods( 80-200nm), 3D urchin-like structure ( about 1-5μm),and nanorods of α-Fe₂O-3 on FTO glass(the length of nanorods 200nm, width of nanrods 40nm).3) In chapter 3 the materials of core/shell structure of α-Fe₂O₃/TiO₂ were also formed by hydrothermal method and were marked by XRD,TEM etc.. Through different composite, concentration of photocatalysts and concentration of reactant, we found the influence of their photocatalysis efficiency.4) In chapter 4 we have synthesized well-aligned ZnO nanorod arrays on F:SnO₂(FTO) substrates by hydrothermal method. We characterized its morphology and crystalline structure by XRD, TEM, and SEM. As well as the photocatalystic property of ZnO.5) In chapter 5 we have synthesized α-Fe₂O₃/ZnO compound materials by hydrothermal method, and characterized its crystlaine structure and morphology by XRD, TEM, and SEM. And we also studied the influence to the photocatalystic efficiency by different mass ratio, catalyst concentration and the dye concentration, etc.6) In the last chapter we made a conclusion. And we give some advice about this work. Through systemic research , we have found the optimal method to prepare catalyzer, wealso make certain the ratio of α-Fe₂O₃/ TiO₂ and α-Fe₂O₃/ZnO. Meanwhile , we research thecondition of photocatalysis reaction. Father research has been made to improve the rate of thereaction.