氧分子的活化与还原:从金属蛋白酶的模拟到燃料电池电催化剂的应用

The oxygen activation/reduction reaction is one of the most important reactions in both life processes and in energy converting systems such as fuel cells, and it has recently being an extensively studied research area. Biomimetic models which resemble the active site of heme-containing enzymes may provide chemical evidence for the clarification of dioxygen activation mechanisms, and may aid to guide the design of biomimetic oxygen reduction reaction (ORR) catalysts for potential applications as well. This proposal will design and prepare a serial of iron porphyrin or heme-copper complexes as chemical models of the active site of heme-containing enzymes including the terminal enzyme of respiratory chain, cytochrome c oxidase. The O2-binding and activation by these model compounds will be investigated by various spectroscopic and electrochemical methods. The objectives of this proposal will be to further clarify the mechanism of O2-binding and activation catalyzed by cytochrome c oxidase, esp.to demonstrate the key transient intermediates that relating to the O-O bonding cleavage; to provide the spectroscopic evidence of different kinds of one-electron reduced heme-dixoygen adducts relating to the intermediates generated by heme-containing enzymes during their different activation pathways; and to design and optimize the bio-inspired ORR catalysts performance, which to be eventually applied for fuel cells cathode electrocatalysts. The results obtained will further sharpen our understanding of the dioxygen activation mechanisms catalyzed by cytochrome c oxidase as well as heme-containing enzymes in the view point of fundamental research; on the other hand, the developed bio-inspired ORR catalysts represent one of the most hopeful non-precious-metal catalysts for next generation of ORR catalyst for fuel cells.

氧分子的活化还原不管在生命过程中还是在能量转换体系如燃料电池中都是一个非常重要的化学反应过程，也是人们广泛研究的热点课题。用模型化合物来模拟金属蛋白酶活性中心的结构与性能，能为解开金属蛋白酶对小分子氧的活化机理提供化学模型证据，并对氧分子仿生还原催化剂的设计与应用发挥指导性的作用。本项目基于含血红素金属蛋白酶的活性中心结构，设计制备一系列含铁卟啉的模型化合物，通过各种光谱学和电化学方法研究氧分子与模型化合物的键合、还原性质。本研究旨在为血红素蛋白酶及细胞色素c氧化酶对氧分子的活化过程中出现的涉及O-O键断裂的各种难观察到的关键瞬态中间体提供相应的化学模型证据;为燃料电池设计优化新型仿生氧分子还原催化剂。该项目的成功实施将在基础研究方面进一步推动生物大分子对小分子氧的活化还原机理的理解；在应用基础研究方面将扩大仿生氧分子还原催化剂在燃料电池贱金属电催化剂上的进一步应用。

氧分子的活化还原不管在生命过程中还是在能量转换体系如燃料电池中都是一个非常重要的化学反应过程，也是人们广泛研究的热点课题。用模型化合物来模拟金属蛋白酶活性中心的结构与性能，能为解开金属蛋白酶对小分子氧的活化机理提供化学模型证据，并对氧分子仿生还原催化剂的设计与应用发挥指导性的作用。本项目基于含血红素金属蛋白酶和漆酶的催化活性中心结构，设计制备了一系列含铁卟啉和多铜配合物作为仿生氧还原反应催化剂，通过各种光谱学和电化学方法研究了氧分子与模型化合物的键合、活化及还原性质。我们成功地捕获了系列关键的氧分子活化的中间体，这对进一步了解金属蛋白酶活化还原氧分子的机理具有非常重要的意义。另外，我们实现了仿生催化剂在石墨烯和碳纳米管等导电载体上的可控制备，通过合理的分子设计成功地实现了对其催化活性和稳定性的调控，并最终将其应用于燃料电池测试，得到了目前为止唯一一个同时具备高催化活性和高稳定性的新型非贵金属氧还原反应催化剂。本项目为寻找将来可替代贵金属铂基催化剂用于燃料电池中能量转换效率高且稳定性好的非贵金属氧还原反应电催化剂提供了新途径。