Cuprous Oxide Microcrystals Controllable Preparation And Properties

Nano-materials are a major discovery in the history of modern science. It is known as the most promising materials in 21st century. It has become the focus and the forefront of the field of Materials Science, arousing widespread concern. Its property is different from conventional materials by their nature, which has the particularity. Nano-materials play an important role in the transformation of traditional industries, the design of new products, as well as the formation of new industries. Cuprous oxide (Cu₂O) is an important inorganic compounds and inorganic chemical raw materials. And it is a p-type semiconductor. Because of a special optical, magnetic, electrical properties, Cu₂O has a wide range of applications in many areas. And sub-micron and nano-scale Cu₂O and composite materials have good prospects in the semiconductor materials, solar energy conversion cells, magnetic storage devices, gas sensor, the fields of Photocatalysis applications because of their unique optical, electrical and magnetic properties. It has attracted attention. The size and morphology of inorganic materials show strong effects on their widely varying physical and chemical properties. So the synthesis of uniform nano- and microcrystals with well-controlled size and morphology has moved into focus in the field of materials science.Hydrothermal method applys to the preparation of crystalline integrity, smaller particle size powder product. The products by this method have high purity , less conglomeration, and narrow particle size distribution. And it has controlled morphology in most cases. In this thesis, the nano-and micron-level Cu₂O was prepared by a simple hydrothermal method in different oleic acid and formic acid system, respectively. Through characterized, the products have better dispersion, particle size uniformity, and homogeneous morphology. In the formic acid system, the morphology of the products can be controlled by changing the reaction conditions . By analyzing preparation conditions and processes of Cu₂O and exploring the growth mechanism of Cu₂O, effective control of its morphology can be achieved in order to its industrial production. Relative to preparation past, the method in this dissertation has virtue such as easy operation, safety, environmental protection, etc. It provides a new train of thought for the preparation of Cu₂O green study.The main content of this thesis include the following two parts:(1)Spherical cuprous oxide nanoparticles were prepared by hydrothermal method using cuprous chloride, ethanol and sodium hydroxide as raw materials. And sodium oleate, oleic acid were used as a surfactant. The results show that good spherical crystalline Cu₂O nanoparticles can be synthesized using oleic acid and sodium oleate as surfactant at 150℃for 24 h. The effects were studied that the experimental conditions affected the crystallization and morphology of the products including the amount of ethanol, oleic acid and sodium oleate and the reaction temperature. The results reveal that reaction temperature has a little impact on the morphology of the product, but it has an impact on the size and the uniformity of particle size of the products. Changing the amount of oleic acid has an impact on the morphology of the product and the uniformity of particle size using oleic acid and sodium oleate system as surfactants; And the amount of ethanol has a greater impact on the dispersion of the products.(2)Cuprous oxide (Cu₂O) microcrystals with controlled morphology was synthesized via a hydrothermal method by reducing copper nitrate with formic acid at 150℃for 2 h. C2H5OH-H2O admixture was used as solvents. Four different morphology of Cu₂O particles can be synthesized by changing reaction conditions including eight-horn-shaped crystal, cube, edge-cut cube, cube with a small 90°notch in every edge. Water content of mixed solvents, adding the ammonia, ethylenediamine, triethylenetetramine and the concentration of raw materials, reaction temperature, and time show effects on the phase formation and morphology of the products . Different concentrations of copper nitrate solution are the key factor in the formation of morphology of Cu₂O crystals. The formation of different morphology of Cu₂O crystal was discussed. By analyzing the UV-vis diffuse reflectance spectroscopy of four different morphology of Cu₂O, the results indicate that Cu₂O microcrystals with regular morphology show enhanced optical absorption compared to that of eight-horn-shaped microcrystals.