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Preparation and characterization of bismuth oxide nanoparticles Analytical Chemistry

Author: JingHuiHua
Tutor: JiangXinYu
School: Central South University
Course: Analytical Chemistry
Keywords: Bi2O3 nanoparticles nanorods controlled synthesis reverse microemulsion
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 409
Quote: 1
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Abstract


The preparation and application of nanometer materials have become a focused research in recent years. Bi is a safe and nontoxic metal. It has received more and more attention for its pollution-free properties. Bi2O3 is an important compound of Bi. It was widely used because of excellent optical, electrical and magnetic properties and catalytic activity. Our country owns the rich bismuth resources. But the product structrue of bismuth is single and Bi2O3 with good property is still need to be imported. So the research on controllable synthesis of Bi2O3 is of significance for increasing the value of Bi resources and promoting the application of Bi2O3 powder. In this paper, we focused on controllable synthesis of Bi2O3. Bi2O3 powders were prepared by reverse microemulsion, polymer-network process and precipitation method. The products were characterized by TEM, SEM, EDS, TG-DSC and XRD. The factors of prepared technology on the product were studied and the possible mechanisms of these reactions were also discussed.In reverse microemulsion, the system of tritonX-100/n-hexanol/ cyclohexane was used for preparing Bi2O3. The nanoparticles with 80-100 nm were obtained. Besides, Bi2O3 with different shapes and dimensionalities were also controllably synthesized. The factors that affect the morphologies of the products were studied. The results revealed that one-dimensional (1D) bismuth oxide precursor nanorods, two-dimensional (2D) hexagonal nanoprisms and amorphous lamellas were obtained. The morphologies of the bismuth oxide precursor were successfully controlled through the adjustment of the molar ratio of water to surfactant w. These morphologies were preserved when annealed at 600℃for 2h. In addition, the morphology of products was also sensitive to the surfactant concentration, the reactants concentration and reaction and aging time. It was found that the growth of hexagonal nanoplates is a function of time. In consideration of the effect of water content, the possible formation mechanism of these nanostructures and the effect of surfactant were also discussed.The Bi2O3 nanoparticles were prepared by polyacrylamide gel route. Acrylamide and N,N’-methylenebisacrylamide were used for formation of polymer-network. TEM investigation revealed the average particle size of B12O3 nanoparticles ranged from 40 nm to 50 nm, The B12O3 crystal phase was sensitive to the calcined temperature and a-Bi2O3 was obtained when annealed at 560℃for 4 h. The size can be controlled by adjusting reactants concentration and pH value of the reaction system.The chemical precipitation method was modified. Bi2O3 micro-tetrahedrons with the edge length of 1-5μm were synthesized in large quantities by a chemical precipitation and refluxing method with BiCl3 and NaOH as reactants in alcohol-water systems. The prepared Bi2O3 was bcc (Υ) phase and had a high degree of crystallinity. The morphology of the final products changed into micro-cubes by increasing the amount of dispersant. The result of the influence of reaction temperature on products revealed that properly improving temperature favors the formation of Bi2O3 crystal. The pure-phaseΥ-Bi2O3, as well as well-defined polyhedron was obtained at the temperature≥75℃

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