Synthesis And The Study Of Properties Of Cuprous Oxide Microcrystals And Titanium Dioxide Nanocomposites

There are more and more organic pollutants in the waste water with the fast development of industry. The environmental pollution is getting worse more and more. It's very important to control the pollution of the organic compound and improve water environmental quality. In these years, photocatalytic redox reactions that use semiconductor as the photocatalyst become the most noticeable waste water treatment method. Photocatalysis is emerging as a promising technology for waste water treatment and water purification. The advantages of this technique over the traditional waste water treatment include complete mineralizaion, high degradation efficiency, and low cost, good stability. Since under normal temperature and air pressure, the organic pollutants could be completely degraded into CO₂, H2O and other mineral acids by the photocatalysis method. TiO₂, as a kind of photocatalyst, can be used to degrade organic contamination with dramatic effects. Heterogeneous photocatalysis can degrade organic pollutants in water efficiently by oxidation utilizing TiO₂ as a catalyst, and has been the subject of extensive research in the field of environmental science recently. However, TiO₂ has several disadvantages as follow:â‘ The high rate of electron-hole recombination on particles results in a low efficiency of photocatalysis.â‘¡TiO₂ may show photocatalytic activity by irradiation of ultra violet light for its wide band gap(Eg=3.2eV), but the proportion of UV light to the sun light is very small and ocupt 4% of all. So as the materials of photocatalysts, the efficiency of light photocatalysis and transform of TiO₂ is low, it can't achieve the level of practical application.â‘¢Because the petroleum organic contamination is always floating on the surface of water, the powder TiO₂ or other carriers will go down into the bottom of water and not achieve the purpose of photocatalytic degradation. The suspensed TiO₂ powder is easy to agglomerate and difficult to recover from solution. Those disadvantages have the photocatalytic oxidation technique of TiO₂ limited practice.Considering the problems above, the research work has been carried out as follow.Therefore, in order to improving TiO₂ photocatalytic activity and improve the effective utilization of solar energy, we give two methods in this study. One approach is to dope transition metals Fe³⁺,Co²⁺,Ni²⁺ into TiO₂, and the another is using the hollow glass microbeads as carrier to form coupled photocatalysts by dip-coating method. In this study, we use Tetrabutyl titanate(Ti(OC₄H₉)₄) as raw materials, Ferric nitrate(Fe(NO₃)₃·9H₂O), cobalt chloride hexahydrate(CoCl₂·6H₂O) and nickel nitrate hexahydrate(Ni(NO₃)₂·6H₂O) as adulterant, a small amount of Acetyl acetone(C₅H₈O₂) is used to adjust solution sol-gel time. The study of M-TiO₂/GMBs for Rhodamine B Photocatalytic Degradation shows that the proportion of doping in the same circumstances (0.1%), doping Fe photocatalytic properties is best, when Fe doping amount is 0.01%, Photocatalytic Degradation rate reaches 98%.But TiO₂ still need activation with UV light source and the potential to utilize sunlight as light energy source to processing sewage always is a goal which the scientist pursues. In 1998, Ikeda etal firstly showed that Cu₂O could decompose H₂ and O₂ in the sunlight. It predicts that Cu₂O may be employed as a promising catalyst under visible light. As we know, the quantum efficiency of bulk Cu₂O is quite low while increase as thescale of Cu₂O transtorm from micrometer to nanoscale. The aim we pray is to synthesize amall-scale microcrystal Cu₂O with uniform morphologies by simple method.In this study, cuprous oxide powder was carried out by electrochemical method with copper electrodes in alkaline solution of sodium chloride. We analyzed the influence of electrolyte composition of the electrolyte temperature, pH value, voltage, time and other conditions on the morphology of microcrystalline Cu₂O and its size with single-factor. And the shape is controlled by us. The growth mechanism is reveals by the from the crystal structure, crystal nucleation and growth point of view. The results show that Cu₂O particles is growth mainly in the region of electric field, the product was pure cubic structure Cu₂O microcrytals; With the temperature increase, the shape tends to the rules and the surface tends to smooth, most particles of the grain became icositetrahedron when the temperature reach to 90℃.; With the increase of pH value, the products become icositetrahedron from the crystal octahedron; With the voltage increased, Cu₂O microcrytals develop hexangular structures with rough surface from icositetrahedron with smooth surface. The best conditions of form uniform icositetrahedron cuprous oxide is: [NaCl]=80g/L, [NaOH]=0.5g/L (pH=12.1), [Na₂Cr₂O₇]=100mg/L, voltage U=2.0V, time t=30min, the temperature T=90℃.In addition, the unavoidable harmful sub-reactions producing impurities of copper powder and Cu(II) compound were observed in experiments. To improve the quality of product, some efforts such as additive Na₂Cr₂O₇ is used to prevent the sub-reactions taken. The products are characterized by X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), and selected-area electron diffraction (SAED), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. A UV-vis spectrum was used to estimate the band gap energy of the microcrystals.