多级孔结构石墨烯基复合材料的制备及其在氧气还原中的应用

The development of high-performance and low-cost oxygen reduction reaction(ORR) catalysts is very important for fuel cell that is one of the most effective devices to solve the energy crisis. However, the replacement of precious metal catalysts by low-cost non-precious metal catalysts often faces the problems of slow mass transfer, low activity and poor stability. This project studies the preparation of non-precious metal based composite catalysts with fast mass transfer, high activity and high stability by the structural design of graphene aerogels and optimization of composite system, and focuses on the related mechanism investigation: 1) By the introduction of hierarchically porous structure and heteroatom into the graphene aerogels, the novel supporting material with fast mass transfer and high activity can be obtained. 2) The novel graphene aerogels can be used to support non-precious metal catalysts to prepare the composite catalysts, exhibiting an enhanced mass transfer and increased activity. To further increase the stability of these composite catalysts and prevent the non-precious metal catalysts from peeling off and dissolution, the ultrathin porous carbon layer, which is carbonized from the polymer layer, is introduced throughout the aerogel networks to anchor the dispersed non-precious metal nanoparticles. Finally, the highly efficient and stable graphene-based ORR composite catalysts with a continuously interconnected sandwich structure (porous graphene skeleton–non-precious catalyst–porous carbon) are prepared.

非贵金属氧气还原反应（ORR）电催化剂，作为一种低成本催化剂材料，对发展燃料电池、解决能源危机问题具有重大意义。然而非贵金属ORR电催化剂往往面临着催化活性不高、稳定性差的问题。本项目拟通过石墨烯气凝胶载体的微观结构设计和复合体系的结构优化，开展兼具快传质、高活性和高稳定性非贵金属ORR复合电催化剂的制备及其机理研究：1）通过在大孔结构石墨烯气凝胶的骨架上引入介孔的结构设计和杂原子的掺杂，研究孔微观结构和杂原子掺杂对气凝胶内部传质和催化性能的影响，调控得到具有快传质和高活性的多级孔结构石墨烯气凝胶载体；2）通过与非贵金属催化剂复合，并引入多孔碳层，构筑石墨烯多孔骨架-非贵金属催化剂-多孔碳三明治结构。优化复合体系中各组分的微观结构，得到兼具快传质、高活性和高稳定性的非贵金属ORR复合电催化剂。探索出一条通过载体微观结构设计和复合体系结构优化制备高性能非贵金属ORR复合电催化剂的有效途径。