Study On Synthesis And Photocatalytic Properties Of Bismuth Based Magnetic Materials

In today’s society, environment pollution and energy crisis is a great challenge of distress and threat to the survival and development of human beings, especially in the special situation of our country, ensure the stability and rapid development of GDP, at the same time, realize the strategic objectives of sustainable development is an enormous challenge that China is facing. These years, light catalytic hydrolysis hydrogen production, photoelectric conversion, photocatalytic degradation of cutting-edge technology and other cutting-edge technologies are the focus of research in the world, these techniques effectively solve the problem of environment and energy with its superior performance. Among them, photocatalytic technology, using sunlight, non-toxic and harmless, inexpensive, reusable characteristics, has an important significance to environmental protection, energy development, economic development and so on.The traditional photocatalyst due to its small size, it is difficult to separate from the reaction solution, especially in the process of photocatalytic treatment of industrial wastewater, if photocatalyst is difficult to recover, it will cause great economic losses. In order to solve this problem, people began to study with magnetic photocatalyst, so as to ensure the photocatalytic efficiency,at the same time, it is convenient for recycling. In this paper we used hydrothermal method successfully synthesized bismuth catalyst, magnetic Bi₂Fe₄O₉ simple substance and P-p type composite heterogenous Bi₂Fe₄O₉/NiFe₂O₄ photocatalyst. The catalysts were characterized by X-ray diffraction（XRD）, scanning electron microscope（SEM）, Fourier transform（FTIR）, ultraviolet visible diffuse reflectance（DRS UV-Vis）, fluorescence（PL） and so on. The specific research contents are as follows:（1）We took Bi（NO₃）₃·5H₂O as the Bi source, Fei（NO3）3·9H2O as the Fe source, with hydrothermal method, sucessfully made Bi₂Fe₄O₉ photocatalyst. The crystal structure, surface morphology, energy band and optical properties of Bi₂Fe₄O₉ were studied by the means of a variety of techniques. We usd the solution of methylene blue（MB）, which was a kind of organic dye, simulate water pollution, investigated the photocatalytic oxidation ability of Bi₂Fe₄O₉ photocatalyst under UV light. Based on the experiment of trapping agent, deeply discussed the mechanism of Bi₂Fe₄O₉ photocatalytic degradation of MB.（2） A certain quality of Bi₂Fe₄O₉ product was put into the preparation process of NiFe₂O₄, the magnetic Bi₂Fe₄O₉/NiFe₂O₄ composite photocatalyst with different mass fraction ratio was prepared by hydrothermal synthesis method. Using a variety of characterization methods to analyze the basic characteristics of Bi₂Fe₄O₉/NiFe₂O₄, electrochemical test results showed that Bi₂Fe₄O₉/NiFe₂O₄ was a P-p type composite heterojunction. Respectively the soulition of MB and Cr（VI） simulated industrial water pollution, we studied the photocatalytic oxidation and reduction capacity of Bi₂Fe₄O₉/NiFe₂O₄ composite photocatalyst under UV light. Magnetic and photocatalytic stability of Bi₂Fe₄O₉/NiFe₂O₄ were evaluated by repeated testing. Based on the results of trapping agent and fluorescence experiments, the catalytic oxidation and reduction mechanism of Bi₂Fe₄O₉/NiFe₂O₄ composite catalysts were studied deeply.