Study On The Coupled Effects Of Cu/ M_xO_y-TiO₂ And Their Photocatalytic Behaviors For Synthesing Crylic Acid From CO₂ And C₂H₄

Surface photocatalysis is an important way of transforming sunlight into chemical energy that can be saved for long time. In this area, designing effective photocatalysts and proper photocatalytic reactions are the key problems to solve. The present paper pays attention to both aspects. On one hand, the influences of the coupled effects on the chemical composition, crystal structure, chemisorption and photo absorption properties of Cu/MxOy-TiO2 (M=V, Cr, Fe, Zn, and Cu) samples were systematically investigated. On the other hand, an atom-economic reaction, direct synthesis of crylic acid from CO2 and C2H4, was chosen as the aim reaction and the relationship between the activity of photocatalysts and their surface composition, structure, photoabsorption and chemisorption properties were studied.1. MxOy-TiO2 binary oxides were prepared by sol-gel method and characterized by techniques of Raman, IR, XRD, TPR and XPS. The results show that the transition structures TiVO4 and (Cr0.88Ti0.12)2O3 are formed in V2O5-TiO2 and Cr2O3-TiO2 samples; the crystal phase transition of TiO2 is promoted by Fe3+ coming into the lattice of TiO2 and three kinds of crystallites of TiO2 (A, R and B) coexist in Fe2O3-TiO2 samples; in ZnO-TiO2 samples, Zn2+ ions do not emerge in the form of ZnO, but in the form of ZnTiO3(C) and ZnTiO3(T); and in CuO-TiO2 samples, only CuO and TiO2(A) are formed. Based on the above results, the character and models of the structure of MxOy-TiO2 were summarized.2. Combining UV-Vis DRS experiments and Kubella-munk function, we found that all the five binary oxides have better photoabsorption properties for both ultraviolet and visible light than TiO2. The UV absorption limit takes red shift and the absorptivity for visible light rises due to the coupled effects of TiO2 and MxOy. Models of the band structure of binary oxides were proposed.3. Coupled oxides with metal modified, Cu/ZnFe2O4-TiO2, Cu/V2O5-TiO2, Cu/Cr2O3-TiO2, Cu/Fe2O3-TiO2, and Cu/ZnO-TiO2, were prepared by sol-gel combined with impregnation method and used as photocatalysts in the aim reaction. The experimental results show that the particle sizes of the five photocatalysts are in nanometer grade. Metallic Cu is thoroughly reduced and highly dispersed on the...