金属-氮掺杂三维有序多孔碳及其有序化膜电极用于聚电解质膜燃料电池性能研究

Developing the non-precious metal catalysts (NPMCs) of high performance and low cost for the oxygen reduction reaction (ORR) and effectively constructing membrane electrode assembly (MEA) have been the effective solution to solve the high cost of Pt-based catalysts and to improve the performance of polymer electrolyte membrane fuel cell (PEMFC). The metal-nitrogen doped three-dimensionally ordered porous carbons (M-Nx-3DOPC) have been reversely copied as the high performance NPMCs through the colloidal crystal templates assembled by the different sizes of SiO2 nanometer microspheres. Furthermore, the ordered MEA is obtained by perfectly transferring the regular catalyst block to the surface of polymer electrolyte membrane. Then, the single PEMFC can be assembled thus to be tested. Combining with the multiple techniques, this project will clarify the structure-function relationship among preparation technology, structural composition and catalytic performance, optimizing the preparation technology and further to improve the catalytic performance. On one hand, M-Nx-3DOPC will be advantageous to high density doping of the active sites, improvement of the mass transfer process and conservation of the original structure due to its higher surface area, porosity as well as the three dimensional periodic network nanostructure. On the other hand, the ordered MEA can effectively build “three-phase reaction zone”, providing order transport channel to improve the efficiency of mass transfer. It will be expected to give the theoretical and experimental instructions for the improvement of the single PEMFC performance by constructing the high-performance NPMCs and developing the ordered MEA.

开发高性能、低成本的非贵金属催化剂及有效构筑膜电极（MEA）是解决氧还原反应用高成本Pt基催化剂和提升聚合物电解质膜燃料电池（PEMFC）性能的有效途径。本项目拟借助不同粒径SiO2纳米微球组装的胶体晶体模板，反向复制构建金属-氮掺杂三维有序多孔碳（M-Nx-3DOPC）作为高性能催化剂；通过将规则结构的催化剂块体完整地转移至聚合物电解质膜表面，开发有序化MEA，实现PEMFC单电池组装测试；结合多种表征技术，阐明“制备工艺-结构组成-催化性能”之间的构效关系，优化制备工艺，提升催化性能。一方面，M-Nx-3DOPC因具有高比表面积、多孔性、三维周期性网络等特性，有利于活性位点高密度掺杂、传质过程改善和原有结构保持；另一方面，有序化MEA可有效构筑三相反应区，提供有序传输通道，提高传质效率。本项目的开展有望通过构建高性能非贵金属催化剂和开发有序化MEA为燃料电池性能提升提供理论和实验指导。

聚合物电解质膜燃料电池（PEMFC）是一种符合绿色化学的、高效能量转换的发电装置，但贵金属铂（Pt）的大量使用限制了其商业化进程。因此，急需设计开发高性能的非Pt电催化剂及对其进行膜电极组件的构筑和评测。金属-氮（M-Nx）掺杂的碳是一类极具代Pt潜力的非贵金属氧还原反应（ORR）电催化剂。本项目设想开发出一类高比表面积以利于活性位点高密度掺杂、多孔性及高孔隙率以利于传质过程改善、三维结构以利于材料稳定等的新型碳纳米结构，即三维多孔碳催化剂。基于此，分别以二氧化硅纳米颗粒、碳材料、氯化钠微晶等为模板，制备了一系列M-Nx掺杂的三维多孔碳催化剂，如有序多孔碳、二元/三元复合碳、碳黑@金属-氮掺杂碳的核壳结构碳等。结合SEM、TEM、N2吸脱附、XRD、XPS、Mössbauer等物理表征方法对多孔碳催化剂的形貌结构、化学组成进行系统表征，通过循环伏安、旋转圆盘/环盘电极等电化学表征手段对催化剂在酸碱介质中的氧还原活性、稳定性及抗毒化性进行测试，借助DFT计算对催化剂活性高低进行分析。此外，将高性能的三维多孔碳作为燃料电池阴极催化剂，实现了膜电极构筑，并进行了PEMFC单电池组装测试，最优的碳催化剂组装的PEMFC单电池性能媲美商业60%Pt/C催化剂。本项目的开展将为燃料电池阴极用新型碳催化剂的开发和膜电极的构筑提供有价值的参考和借鉴。