铁氧体纳米复合材料的可控制备及其催化性能研究
发布时间：2018-07-30 07:15
【摘要】：纳米复合材料兼具不同材料的多功能性,越来越引起科技工作者们的广泛关注。纳米材料的微观结构往往对其性能有着巨大的影响,并且多阶纳米复合材料的制备中也存在着选择性生长的问题。本论文主要研究Ag-MxFe3-xO4(M=Co,Mn)纳米复合材料的可控制备及形变,通过对不同结构复合材料催化性能分析,探索纳米复合材料的结构与性能之间的关系,并采用硫化形变的方法摸索多阶纳米复合材料的选择性生长规律。主要研究内容如下:(1)采用种晶生长法制备出Ag@MxFe3-xO4核壳纳米颗粒,通过导电炭黑负载制备得到Ag@MxFe3-xO4/C,进而利用纳米银内核在饱和氯化钠溶液中的氧化溶出制备得到空心MxFe3-xO4/C。通过不同材料在碱性溶液中的氧还原反应(ORR)催化性能分析,发现Ag@MxFe3-xO4/C的催化活性和导电性都明显优于空心MxFe3-xO4/C。由此推理,纳米银内核不仅可以提高纳米复合材料的导电性,而且其协同作用有利于增强过渡态金属铁氧体的ORR催化性能。(2)采用种晶生长法制备出Ag-MFe2O4异质纳米颗粒,通过导电炭黑负载制备得到Ag-MFe2O4/C,进而利用纳米银在饱和氯化钠溶液中的氧化溶解制备得到MFe2O4/C、Ag+MFe2O4/C。通过不同材料在碱性溶液中的ORR和析氧反应(OER)催化性能分析,发现Ag-MFe2O4/C的催化活性明显优于Ag/C、MFe2O4/C和Ag+MFe2O4/C。由此推理,Ag和MFe2O4纳米晶之间的直接耦合和电子转移有助于增强过渡态金属铁氧体的电催化活性。此外,Ag-MFe2O4/C也表现出良好的循环稳定性和抗甲醇毒性。因此,Ag-MFe2O4/C可以作为一种优异的双功能性非Pt/C电催化剂。(3)通过分析Ag-CoFe2O4核壳和异质纳米颗粒的硫化形变过程,探究多阶纳米复合材料的选择性生长规律。针对硫化产物,结合软硬酸碱理论对其形成机理进行分析,并对其磁学性能和光学性能进行了表征。结果发现,CoS/Ag2S-空心Fe2O3纳米复合材料在常温下兼具超顺磁性和近红外荧光性能。
[Abstract]:Nanocomposites, with the versatility of different materials, have attracted more and more attention of science and technology workers. The microstructure of nanomaterials often has a great influence on their properties, and there is also a problem of selective growth in the preparation of multi-order nanocomposites. In this paper, the controllable preparation and deformation of Ag-MxFe3-xO4 nanocomposites are studied. The relationship between the structure and properties of the nanocomposites is explored by analyzing the catalytic properties of the composites with different structures. The selective growth of multi-order nanocomposites was studied by means of vulcanization deformation. The main research contents are as follows: (1) Ag@MxFe3-xO4 core-shell nanoparticles were prepared by seed crystal growth method. AgMxFe3-xO4 / C was prepared by conducting carbon black loading, and then hollow MxFe3-xO4 / C was prepared by oxidation dissolution of the nano-silver core in saturated sodium chloride solution. The catalytic activity and conductivity of (ORR) for oxygen reduction reaction of different materials in alkaline solution were analyzed. It was found that the catalytic activity and conductivity of Ag@MxFe3-xO4/C were better than that of hollow MxFe3-xO4 / C. Therefore, the nano-silver core can not only improve the electrical conductivity of the nanocomposites, but also enhance the ORR catalytic performance of the transition metal ferrite. (2) the heterogeneous Ag-MFe2O4 nanoparticles were prepared by seed crystal growth method. Ag-MFe _ 2O _ 4 / C was prepared by conducting carbon black loading, and then prepared by oxidation dissolution of nano-silver in saturated sodium chloride solution to obtain MFe _ 2O _ 4 / C _ (10) Ag. By analyzing the catalytic properties of ORR and (OER) in alkaline solution, it is found that the catalytic activity of Ag-MFe2O4/C is better than that of Ag / C / MFE _ 2O _ 4 / C and Ag / M _ Fe _ 2O _ 4 / C respectively. It is concluded that direct coupling and electron transfer between Ag and MFe2O4 nanocrystals can enhance the electrocatalytic activity of transition metal ferrites. In addition, Ag-MFe _ 2O _ 4 / C also showed good cycling stability and anti-methanol toxicity. Therefore, Ag-MFe _ 2O _ 4 / C can be used as an excellent double-functional non-Pt/C electrocatalyst. (3) the selective growth of multi-order nanocomposites is investigated by analyzing the vulcanization deformation process of Ag-CoFe2O4 core-shell and heterogeneous nanoparticles. The formation mechanism of the vulcanized product was analyzed with the theory of hard and soft acid-base. The magnetic and optical properties of the vulcanized product were characterized. The results show that CoS- / Ag2S- hollow Fe2O3 nanocomposites have both superparamagnetic and near infrared fluorescence properties at room temperature.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36
本文编号：2154249
[Abstract]:Nanocomposites, with the versatility of different materials, have attracted more and more attention of science and technology workers. The microstructure of nanomaterials often has a great influence on their properties, and there is also a problem of selective growth in the preparation of multi-order nanocomposites. In this paper, the controllable preparation and deformation of Ag-MxFe3-xO4 nanocomposites are studied. The relationship between the structure and properties of the nanocomposites is explored by analyzing the catalytic properties of the composites with different structures. The selective growth of multi-order nanocomposites was studied by means of vulcanization deformation. The main research contents are as follows: (1) Ag@MxFe3-xO4 core-shell nanoparticles were prepared by seed crystal growth method. AgMxFe3-xO4 / C was prepared by conducting carbon black loading, and then hollow MxFe3-xO4 / C was prepared by oxidation dissolution of the nano-silver core in saturated sodium chloride solution. The catalytic activity and conductivity of (ORR) for oxygen reduction reaction of different materials in alkaline solution were analyzed. It was found that the catalytic activity and conductivity of Ag@MxFe3-xO4/C were better than that of hollow MxFe3-xO4 / C. Therefore, the nano-silver core can not only improve the electrical conductivity of the nanocomposites, but also enhance the ORR catalytic performance of the transition metal ferrite. (2) the heterogeneous Ag-MFe2O4 nanoparticles were prepared by seed crystal growth method. Ag-MFe _ 2O _ 4 / C was prepared by conducting carbon black loading, and then prepared by oxidation dissolution of nano-silver in saturated sodium chloride solution to obtain MFe _ 2O _ 4 / C _ (10) Ag. By analyzing the catalytic properties of ORR and (OER) in alkaline solution, it is found that the catalytic activity of Ag-MFe2O4/C is better than that of Ag / C / MFE _ 2O _ 4 / C and Ag / M _ Fe _ 2O _ 4 / C respectively. It is concluded that direct coupling and electron transfer between Ag and MFe2O4 nanocrystals can enhance the electrocatalytic activity of transition metal ferrites. In addition, Ag-MFe _ 2O _ 4 / C also showed good cycling stability and anti-methanol toxicity. Therefore, Ag-MFe _ 2O _ 4 / C can be used as an excellent double-functional non-Pt/C electrocatalyst. (3) the selective growth of multi-order nanocomposites is investigated by analyzing the vulcanization deformation process of Ag-CoFe2O4 core-shell and heterogeneous nanoparticles. The formation mechanism of the vulcanized product was analyzed with the theory of hard and soft acid-base. The magnetic and optical properties of the vulcanized product were characterized. The results show that CoS- / Ag2S- hollow Fe2O3 nanocomposites have both superparamagnetic and near infrared fluorescence properties at room temperature.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O643.36
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