多孔骨架材料的合成及其储氢性能研究

The goal of this research is to design and synthesis of metal organic porous materials (MOPMs) with high hydrogen storage. For this, we choose mechanochemical methods to construct the MOPMs. In this technique, neat mixtures of linker molecules and metal salts are ground together in a ball mill to produce the desired MOPMs. Mechanochemical synthesis is a solvent-free methodology, which may avoid large quantities of solvent molecules in the pores of MOPMs. As a result, the as-synthesized compounds may have a higher effective surface areas and hydrogen storage capacities. It is known that for MOPMs a high specific surface area is a necessary prerequisite for reaching a high storage capacity. Moreover, organic ligands play the key role to tune the pore size and surface area of the MOPMs. Our strategy for creating such MOPMs with high hydrogen storage capacities is based on using rigid organic linkers with aromatic backbones such as phenylene, aphthalene, bipyridine, and biphenylene. Generally, many factors may have a dramatic impact on the structures and properties of MOPMs during the mechanochemical reaction, such as the grinding parameters (time and power), temperature, metal salts, organic ligands, solvent and the molar ratio of starting materials. Therefore, our studies will focus on exploring these influencing factors to find out the relationship between structures and hydrogen storage capacities of MOPMs. It is believed that the rational design and controlled synthesis of MOPMs with high hydrogen storage capacities will come true.

本项目致力于高储氢，或气体储能金属有机多孔材料的设计合成及性质研究。拟选用机械混合法，通过有机配体和金属盐固体均匀混合并研磨制得预想中的金属有机多孔材料。该方法是真正的"无溶剂"的绿色合成方法，可以有效地避免客体溶剂分子对金属有机多孔材料孔道的堵塞，提高材料的有效比表面积，达到提高储氢量的目的。一般说来，金属有机多孔材料比表面积的大小将直接影响其氢气存储量的大小，而有机配体在调控多孔材料的孔径尺寸和比表面积大小方面起着关键性的作用。因此，本课题计划设计长链刚性大配体来进行具有超大比表面积的储氢材料的合成研究，进而获得储氢性能优良的材料。本项目也将系统地研究球磨时间和频率、反应温度、金属源、配体的修饰、添加极少量溶剂以及反应物比例等条件对产物结构、性能的影响，总结机械混合法的合成规律，详细地研究所合成材料的结构与储氢性能之间的关系，实现具有高储氢性能的金属有机多孔材料的设计合成。

项目围绕机械混合法开展具有高氢气存储性能的金属-有机多孔材料的合成工作。实验结果表明，通过有机配体和金属盐固体均匀混合并研磨很难获得预想中的金属-有机多孔材料。目前文献报道的利用机械混合法所制备的金属-有机多孔材料也只是有一些结构简单的化合物。因此，我们适当调整项目研究计划，以水/溶剂热法为研究手段，开展具有不同性能的金属-有机多孔材料的合成研究。我们利用同时含有“N”和“O”原子的有机配体构筑具有不同结构和性能的金属-有机多孔材料。通过项目的实施得到了若干结构新颖的金属-有机骨架材料，部分材料还展示出非常好的荧光性能和热稳定性。上述研究内容目前已经发表SCI论文6篇，国内核心期刊收录论文1篇，授权国家发明专利3项，培养硕士研究生6人，协助培养博士研究生1人。