基于3D-Hofmann骨架普适性构筑Pt基双金属原子催化剂及其氧还原性能研究

How to fabricate the Pt-based catalysts with high atomic utilization, high activity and high selectivity is a key scientific issue in the field of proton exchange membrane fuel cells (PEMFCs). In order to solve this problem, this project takes Pt-based bimetallic atomic catalyst as the research object, and intends to carry out the following research contents. Cyanide-bridged three-dimensional Hofmann-type coordination frameworks are used as precursors. The migration mechanism of metal atoms during pyrolysis can be found out by in-situ transmission electron microscopy. Hence we can obtain a universal principle and new method for constructing Pt-(Fe、Ni、Cu) bimetallic atomic catalysts. Microstructure characterizations and electrochemical methods are used to investigate the influence of chemical composition and microstructure on catalytic performance. Therefore, the relationship between active center and its catalytic activity, stability and selectivity could be clarified. The synergistic catalytic mechanism of neighboring atoms and the structure-property relationship between Pt-based atomic catalysts and ORR performances are revealed by density functional theory calculation method. In conclusion, this project aims to promote the further research of new type Pt-based oxygen reduction catalysts, meanwhile provide a theoretical basis for further development of PEMFCs.

如何构筑兼具高原子利用率、高活性和高选择性的Pt基氧还原催化剂是当前质子交换膜燃料电池领域亟需解决的关键科学问题之一。为了解决这一问题，本项目以Pt基双金属原子催化剂为研究对象，拟开展以下研究内容：采用三维Hofmann型氰基桥联纳米多孔配位骨架材料为热解煅烧前驱体，借助原位透射电镜查明热解过程中金属原子的迁移运动规律，获得普适性构筑Pt-(Fe、Ni、Cu)双金属原子催化剂的新原理和新方法；结合物性表征和电化学测试手段，研究Pt基双金属原子催化剂化学组成、微观结构与电化学性能之间的关系，获得双金属活性中心及其配位构型对氧还原催化活性、稳定性、选择性的影响规律；采用密度泛函理论计算方法，研究Pt基双金属原子催化剂的催化反应过程，揭示近邻原子的协同催化机理及双金属原子复合结构与氧还原性能间的构效关系。本项目的实施将为新型、高效Pt原子氧还原催化剂的开发提供实验依据和理论基础。

降低贵金属用量、提升催化剂的活性与稳定性是目前阴极氧还原催化剂的研究热点和难点，也是质子交换膜燃料电池推广应用的必经之路。本项目以金属活性中心调控及非金属原子优化配位构型两种手段，构建和开发了多种兼具高原子利用率、高活性及高稳定性的新型氧还原催化剂。主要结果有：（1）通过筛选金属前驱体和碳载体以及杂原子掺杂手段，高温热解制备了系列过渡金属（Co、Fe）/杂原子共掺杂碳基催化剂；结合物性表征和电化学测试手段，阐明了复合催化剂化学组成、微观结构与氧还原催化活性、稳定性、选择性之间的关系。（2）以Ni基和Pt基Hofmann骨架为热解前驱体，构筑一系列具有独特形貌的NiFe/NC和PtFe金属间化合物催化剂。通过Hofmann骨架金属中心和有机配体调控等手段，对衍生的碳材料催化剂中的活性位点进行调控，探讨了活性位点种类及杂原子对催化剂氧还原催化性能的影响。本项目为新型氧还原催化剂的开发和应用提供了实验依据和理论指导。