零价铁纳米微米空心球的非模板法合成与磁性研究

Hollow nano- to micro-spheres of iron have extensive potentials in such field as microwave electromagnetic materials, drug delivery, catalyst and its carriers, etc. However, few reports are about the synthesis of hollow nano- to micro-spheres of iron, for there are difficulties when traditional templating method are used to obtain this kind of materials. Now, researchers often take the advantages of Ostwald ripening, a well-known physicochemical phenomenon, to construct the structure of hollow spheres. When Ostwald ripening process takes place in the aggregates of primary nanoparticles, the dissolution of the interior smaller crystallites will lead to the formation of hollow spheres. In this research project, we plant to prepare spherical aggregates of primary iron nanoparticles at first, by controlling the reaction parameters of liquid phase reduction. Then, hollow nano- to micro-spheres of iron are prepared by aging or hydro-/solvent-thermal treating iron aggregates of primary nanoparticles under proper conditions. Influences of the reaction parameters on the morphology and structure of the resulted materials are planed to be investigated, and the Kinetic Mechanisms will be discussed. Static magnetic properties, microwave electromagnetic properties will be characterized; and the structure-property relationship will also be studied. In addition, we will try to develop a flexible, efficient non-templating method to construct nano- to micro-spheres of metal, and lay a good foundation for the potential application in microwave electromagnetic materials, magnetic carriers of targeted-drug, etc.

铁纳米微米空心球在微波电磁材料、药物传输、催化剂及其载体等领域具有很大的应用潜力。由于一些技术上的困难，合成这种材料的文献报道一直很少见。Ostwald熟化这种普遍存在的物理化学现象现已被经常用于构建材料的纳米微米空心球结构。一次纳米粒子球形聚集体发生由内至外的Ostwald熟化现象时，其内部尺寸较小的一次粒子逐渐溶解而形成空心球。本项目拟通过对液相还原反应参数的控制，首先形成由一次铁纳米粒子组装成的铁纳米微米实心球，然后对其进行控温陈化或水/溶剂热处理以发生Ostwald熟化而形成铁纳米微米空心球。本项目将考察反应参数对空心球尺寸、球壳厚度等结构的影响，探讨反应的动力学机理；表征材料的静磁性能、微波电磁性能等并研究其构效关系。另外，开展本项目，还将发展纳米微米空心金属球的通用、高效液相非模板合成法，并为微波电磁材料、磁靶向药物载体等领域的潜在应用打下良好基础。

零价铁纳米微米空心球在电磁材料、药物传输、催化剂及其载体等领域具有很大的应用潜力。由于技术上的困难，合成这种材料的文献报道一直很少见，通常用于制备其他纳微空心球材料的模板法未能成功应用于零价铁纳微空心球的合成。本项目期望在溶液相中利用螫合剂辅助的Ostwald熟化机理制得零价铁纳微空心球，该预期目标已经实现。我们通过液相还原反应首次制得了由一次铁纳米粒子原位组装而成的介孔零价铁纳微球，通过调节反应参数，实现了对介孔零价铁球尺寸及形貌结构的控制，分析提出了介孔零价铁球的形成是螫合剂的诱导效应、纳米粒子表面能降低效应以及副产物H2气泡的阻隔共同作用的结果。所合成的介孔零价铁球能在pH中性条件快速地将硝基苯转化为易被微生物降解的苯胺，并能快速地使高毒性的Cr(VI)转化为低毒性的Cr(III)。通过氯化亚铁、乙二胺、硼氢化钠的混合水溶液在密闭反应釜中的保温反应，制得了零价铁空心球。在该反应中首先生成的是一次铁纳米粒子原位组装的零价铁球，随后发生络合剂辅助的Ostwald熟化效应而出现由内到外的空化现象，形成了零价铁空心球。这是首次利用溶液相中的Ostwald熟化效应制得零价铁空心球。通过调节反应参数，可实现对零价铁空心球的空腔大小和球壳微结构的有效控制。本项目中制得的材料在环境治理方面具有重要的应用潜力，本项目发展的方法可望扩展到其他金属的介孔和空心球材料的合成中。