基于内嵌钴/氮掺杂多孔碳三维石墨烯笼的抗团聚高效氧还原电催化剂

Caging Porous Co-N-C Nanocomposites in 3D Graphene as Active and Aggregation-Resistant Electrocatalyst for Oxygen Reduction Reaction

氧还原反应是决定燃料电池、金属-空气电池等多种新型清洁能源存储与转化技术之性能与应用的关键反应.铂及其合金是目前催化活性最好的氧还原反应催化剂,但其高昂的成本限制了规模化应用.在小尺寸效应作用下,微纳米结构催化剂颗粒在电极制备与电化学反应过程中的团聚限制了催化剂本征催化活性的充分发挥.本文基于喷雾热解技术,发展了一种基于内嵌钴/氮掺杂多孔碳三维石墨烯笼的高活性、抗团聚非贵金属氧还原反应催化剂.此结构中,金属有机骨架化合物ZIF-67衍生的钴/氮掺杂多孔碳纳米结构是催化氧还原反应的活性中心,包覆其外的三维石墨烯笼不仅可在钴/氮掺杂碳纳米结构之间构建连续的三维载流子传导网络,且可高效抑制其在催化剂制备与电化学反应过程中的团聚与活性损失.在碱性电解液中,此类非贵金属催化剂表现出可与铂基催化剂媲美的氧还原反应活性和优异的稳定性.

Oxygen reduction reaction(ORR) is the cornerstone reaction of many renewable energy technologies such as fuel cells and rechargeable metal-air batteries.The Pt-based electrocatalysts exhibit the highest activity toward ORR,but their large implementation is greatly prohibiting by unaffordable cost and inferior durability.During electrode manufacturing and electrochemical reaction,severe aggregation of catalyst nanoparticles induced by size effect further limits the operational performance of electrocatalysts.We report a new strategy for fabrication of active and aggregation-resistant ORR electrocatalyst by caging metal-organic frameworks derived Co-N-C nanocomposites in permeable and porous 3D graphene cages via sprayed drying the mixed colloids of ZIF-67 nanoparticles and graphene oxide,followed by annealing.The 3D graphene cages around Co-N-C nanocomposites not only provide a continuous conductive network for charge transfer,but also prevent the active phase from aggregation during electrode manufacturing and electrochemical reactions.When evaluated as an ORR electrocatalyst,the material exhibited comparable activity but superior stability to commercial Pt/C catalyst in an alkaline electrolyte.