基于金属有机膦酸的高导电性质子导体的研究

Proton Exchange Membrane (PEM) fuel cell technology has received great attentions owing to its wide application foreground as a type of clean energy. PEM is an important component of fuel cells. And both the high proton conductivity and high stability are two of the important factors for evaluating a PEM. Traditional organic or inorganic proton-conducting materials have their own shortcomings in thermal stability, chemical durability and proton conductivity, respectively. Hence, development of new types of proton-conducting materials is one of the most important issues in fuel cell technology. Metal organic frameworks (MOFs) have been investigated as possible candidates for proton-conducting applications in the last decade due to their crystallinity, chemically functionalizable pores and options for systematic structural variation. In this project, we expect to achieve a series of novel proton-conducting materials based on metal phosphonates. Due to the high stability and highly tunable nature of metal phosphonates, they are an excellent platform to develop structure–proton conduction relationships. The results are conductive to the targeted design of better proton conductors with high proton conductivity and high stability. Furthermore, investigation of proton conduction of single crystal samples along different directions can give useful information for understanding the proton dynamics and the mechanisms of proton conduction.

质子交换膜燃料电池作为一类具有广泛应用前景的清洁能源越来越受到人们的关注。质子导电膜是其核心部件之一，材料质子导电性的优劣决定了燃料电池的品质性能。传统的无机质子导体和有机聚合物质子导体在材料的导电性、热稳定性、化学稳定性等方面都存在各自的缺点。因此探求导电率高、稳定性好的质子导电材料是质子交换膜燃料电池发展的重要动力。金属有机框架化合物（MOFs）具有结晶性好、孔洞排列规则、孔洞大小可设计剪裁、骨架有一定柔性的特点，因此它们不仅可以作为潜在的质子导体，而且可以深入研究质子导电的机理。本项目以金属有机膦酸化合物为研究主体，利用其结构设计性好、稳定性高的优点，系统地研究材料结构和导电性之间具有怎样的构效关系，探求导电率与Nafion膜相当、稳定性好的金属有机膦酸质子导电材料。并通过对材料单晶各向异性导电性质的研究，深入理解质子传输通道对导电性质的影响规律，阐明材料中质子传导的机理。

研究计划的重点是寻找一类金属有机膦酸质子导体材料，兼顾高电导率和高稳定性，并深入研究材料的构效关系，阐明质子导电的机理。我们利用高价态金属离子作为金属节点，增强金属有机膦酸这类无机-有机杂化材料的化学稳定性；利用金属离子路易斯酸性调节配位水上质子的电离能力；调变金属离子价态及金属与配体的比例，增加膦酸基团的质子化程度；利用材料的多孔性引入酸性客体分子或亲水性溶剂分子；利用大尺寸单晶进行单晶阻抗谱测量，研究质子传输的各向异性，揭示传输途径的差异。在关注高的质子导电性能同时，我们也探索了不同物理性质如磁性、气体吸附、介电性质与导电性质的耦合或复合。相关的研究结果已在期刊Chem. Commun.、Inorg. Chem.、Dalton Trans.和Cryst. Growth Des.上发表标注项目号研究论文5篇，还有部分结果正在整理投稿中。另外，我们根据已有文献并结合项目所取得的研究成果，分别综述了金属配体策略构筑功能金属有机膦酸材料以及质子导电金属有机膦酸材料的设计合成策略，发表在Chem. Commun.和Coord. Chem, Rev.上，均标注项目号。项目已培养博士后1名，硕士研究生2名。项目按照预定计划开展，基本达到了预期设想。