非掺杂纳米碳材料作为氧还原催化剂的设计、制备、性能及其催化机理研究

Due to the high efficiency and environment-friendlyness, fuel cell has become one of the most important new energy technologies in the 21st century. To reduce the over-dependence on the noble-metal resource of proton exchange membrane fuel cell (PEMFCs) and to enrich the nanocarbon material which can be used as catalyst for PEMFCs,this project will design and prepare non-doped nanocarbon materials with proper edge or defective carbon atoms, including carbon nanotubes and graphene catalysts based on the electron and geometric effects. Through electrochemical kinetics study, advanced in-situ spectroscopic means, and density functional theory (DFT) calculation, we attempt to explore the relation between the edge or defective carbon atoms and the electrocatalytic activity for the oxygen reduction reaction (ORR), to understand the formation and transformation of catalyst surface species on the molecular level, and to unravel the mechanism of the oxygen activation and ORR process. Based on the mechanism insights, we will design rationally and develop novel non-doped nanocarbon catalyst with high performance to push the commercialization of PEMFCs. This research will provide a solid scientific foundation for the catalytic material development of new generation fuel cells.

高效、环境友好的燃料电池技术是21世纪最热门的新能源技术之一。为减少质子交换膜燃料电池对贵金属资源的过度依赖，在质子交换膜燃料电池阴极氧还原催化剂方面进一步丰富可用纳米碳材料的范围，本项目从电子效应和几何效应的角度出发，设计并合成具有适量边缘或缺陷碳的非掺杂纳米碳催化材料，主要包括：碳纳米管和石墨烯，用做质子交换膜燃料电池阴极氧还原催化剂；通过电化学测试手段和动力学分析方法以及原位光谱表征技术，结合密度泛函理论模拟计算，分析非掺杂纳米碳材料中边缘或缺陷碳对非掺杂纳米碳材料氧还原性能的影响规律，原位动态考察反应条件下催化剂表面物种的形成和转化，阐释非掺杂纳米碳材料活化分子氧的机制与氧还原反应机理；设计、开发适合质子交换膜燃料电池阴极氧还原反应的高性能非掺杂纳米碳催化材料，为新一代燃料电池催化材料发展奠定坚实的科学理论基础。

高效、环境友好的燃料电池技术是 21 世纪最热门的新能源技术之一。为减少质子交换膜燃料电池对贵金属资源的过度依赖，在质子交换膜燃料电池阴极氧还原催化剂方面进一步丰富可用纳米碳材料的范围，本项目设计并制备富含边缘或缺陷碳的碳纳米管和石墨烯，用做氧还原催化剂，并考察其催化氧还原机理。首先利用化学刻蚀制备了边缘/缺陷碳纳米管，考察边缘/缺陷对氧还原的影响，并采用密度泛函理论计算并比较边缘/缺陷碳原子及基面碳原子对氧吸附的差别，理论分析边缘/缺陷碳提高氧还原催化性能的原因；然后利用催化刻蚀法来实现边缘/缺陷碳纳米管和石墨烯的可控制备，即将过渡金属（氢）氧化物负载于碳纳米管或氧化石墨烯表面，利用它与碳材料在高温时发生碳热反应，实现碳纳米管或石墨烯的刻蚀，酸洗除去金属颗粒，得到富含边缘或缺陷的碳纳米管或石墨烯，这些缺陷或边缘具有高的氧还原催化活性，从而实现非掺杂边缘或缺陷碳材料的高氧还原催化性能，通过控制负载金属的含量即可实现刻蚀碳材料边缘或缺陷位的控制。考察了边缘碳对碳材料氧还原和电子传导的综合影响。通过动力学分析和多种表征手段，对边缘/缺陷碳材料的氧还原机理进行分析。该项目研究成果为新一代燃料电池催化材料发展奠定坚实的科学理论基础。