Preparation And Catalytic Properties Of Titanium Dioxide And Cuprous Iodide Nanomaterials

The aims of this thesis is to investigate the preparation and catalytic properties of TiO₂ and CuI crystals with nanosize and to explore the relationship between the property and the structure. This thesis reviewes nanomaterials, Nanotitania and nanocuprous iodide, including TiO₂ and CuI crystals with nanosize preparation methods and catalytic properties. Focus on the course of nanotitania as catalyst. Cuprous iodide has important applications in cross-coupling of organic synthesis reaction.The nanotitania was prepared from titanium tetrachloride precursor by sol-gel method, solvent-thermal method and two-step method that involving sol-gel and hydrothermal treatments and characterized with XRD and SEM techniques. The results indicated that the phase of the nanotitania prepared by sol-gel method with an average diameter of 7-16 nm or so was rutile; The phase that prepared by two-step method was anatase with an average diameter of 21-50 nm or so; the phaseof the nanosized TiO₂ prepared by solvent-thermal method was was determined by calcined temperature with 30-40 nm or so. The particles of distribution were uniform with the three methods. The yield of nanotitania was more than 90 % by sol-gel method and two steps method, but was 85 % by solvent-thermal method. The particles size could be increased with extended aging time and increasing calcined time and temperature, but the effects of calcined time to particles size was greater than the aging time and calcined temperature. The extension of the aging time and calcined time didn't change crystal phase. But with the calcined temperature increasing, the crystal gradually changed from anatase phase and brookite phase to rutile phase. Photocatalytic activity was evaluated by measuring decomposition vitamin B₁₂ exposed to UVA(320-400 nm) radiation. The results indicated that there was no significant degradation of vitamin B₁₂ under the absence of illumination only or Nanotitania was existed without light.Through tracking of vitamin B₁₂ degradation, found the vitamin B₁₂ was significantly decreased in the photocatalytic degradation process and thus predicted cobalt porphyrin open-loop in the degradation process by analyzing the Raman spectra. The basic position of peak had not changed, nor the emergence of new absorption peak in the process of degradation, nor new material production and accumulation. The vitamin B₁₂ degradation was direct mineralization. The as-preparation rutile nanotitanium dioxide could minerize vitamin B₁₂. The catalytic result indicated that as-prepared nanocrystals had relatively large surface area, so showing high photocatalytic activity.The cuprous iodide was prepared from Cu(Ac)₂.H₂O and KI as raw materials in aqueous solution and methanol solution and ethanol solution with polyethylene glycol and N₂H₄.H₂O. The yield all was over 90 % by the above methods. The cuprous iodide was characterized with XRD and SEM tools. The results showed that the as-prepared samples were theγ-CuI with octahedral and rod morphology. Theγ-CuI was the octahedral nanocrystals in aqueous system and the dimensions side length was 50-300 nm and was nanorod in methanol solution and the diameter was 300 nm and lengths up to 3μm and was nanorod in anhydrous ethanol solution with diameters from 100 to 400 nm and lengths up to 3μm. The experimental results indicated: Theγ-CuI morphology could be changed by changing the solvent and PEG molecular weight could be controlled the size and length.Using nanooctahedrals CuI, nanorods CuI and commercial CuI as catalysts, progressed free palladium Sonogashira reaction and characterize organic products by MS, 1H NMR and 13C NMR spectrums. The yield of products up to 95 % was higher than the commercial CuI. The yield of octahedral shapeγ-CuI particle was the highest to the short and the long rods.This indicated that the yield of Sonogashira reaction was affected by the catalytic surface area. With the as-prepared CuI progressed free palladium sonogashira reaction had accessed to cheap, highly efficient and high catalytic activity and has considerable academic value.The as-prepared Fe₃O₄ nanoparticles was prepared by solvent-thermal method with FeCl3 as raw materials in ethylene glycol solvent used triethylamine as the template. The dispersion of nanoparticles by solventhermal method was superior and the nanoparticles had a greater surface- area. The reaction materials were simple and the reaction temperature was low compared to the other literatures. The nanospherical particles Fe₃O₄@SiO₂ was prepared with self-made magnetic nanoparticles.Finally, the nanocomposite particles of Fe₃O₄@SiO₂@CuI and Fe₃O₄@SiO₂@TiO₂ were prepared with Fe₃O₄ as matrix. The yieldwas more than 90 % during the experiment step. The structure of the Fe₃O₄nanoparticlescould affect the structure of composite particles and for the further application ofcuprous iodide and titanium dioxide laid a solid foundation.