碳-铁原子聚集体固溶“焊接”石墨烯

The optimized interfacial connection of graphene (G) sheets is the key challenges of extending the unique intrinsic properties of nanoscale G sheets to macroscopic G films. Based on applicant’s previous research on the relationship between interfacial structure and the resultant mechanical behaviour of G based materials, a hypothesis is proposed that: in qusi-2D scale, the alloying solid solution interface bonding (“soldering”) between G sheets and the assemblies of iron atoms (AoFe: nanoparticles, 2D atomic layer and tiny clusters) is an favoured interfacial mode to bridge G sheets and retain the extraordinary properties of G sheets. This project is proposed to adopt the approaches of liquid-phase self-assembly, plasma and heat treatment to make G- AoFe interfacial connections; varying the G surface functional groups, the precursor of iron atoms and fabrication methods to optimize the interfacial microstructures and evaluate the mechanical, conductive and optical properties in both microscopic and macroscopic scales. Seeking the proof of potential connection modes between G and AoFe and revealing the “soldering” effects on the atomic structure changes. Comparing the other interfacial bonding modes, establish the relationship between microscopic interfacial structure and macroscopic properties and validate the “soldering” connection mode is a preferred low dimensional “surface-point” interfacial structure, which is our project’s main scientific focus. Carbon and iron are human friendly elements, introducing the iron-carbon solid solution theory and phase diagram into atomic scale, the project will provide new pathway on developing new G based functional films and extend our vision on traditional steel.

石墨烯二维界面连接,是将其优异微观理化性能贯穿延伸至宏观薄膜态过程中面临的核心挑战。申请人在已有对石墨烯界面结构与宏观力学性能的研究基础上，提出并寻证假说：在准二维尺度上，铁原子聚集体（纳米颗粒、单层原子、团簇）与石墨烯的合金固溶体键合态(“焊接”)，是桥接石墨烯微片、保留优异低维性能的一种较理想界面结构。本研究拟采用液相自组装、等离子体或热处理线路制备石墨烯-铁连接态，调控石墨烯表面官能团、铁的前驱物和制备方法，优化连接点界面微观结构，以宏观和微观薄膜力学、传导和光学等性能为评价体系，寻求铁-碳键合类型证据并阐明接触界面在“焊接”前后键合结构变化。比较研究其它界面结合方式，建立微观界面结构与宏观性能间的构效关系，验证“焊接”键合结构是理想的低维“面-点”界面形态这一关键科学问题。碳和铁都是人类友好元素，本课题将铁-碳固溶体与相图理论引至原子晶体层次，为石墨烯功能薄膜和钢铁研发提供新思路。

铁与碳原子键合结构多样，可形成结构、性能、用途丰富各类材料，在以催化工业为代表的国民经济中扮演重要角色。石墨烯是碳-碳sp2 杂化的二维原子晶体，具有优异的力学、传导和化学可加工性等优异性能，探求石墨烯表面碳原子与铁原子存在状态，键合结构，对开发新一代纳米功能材料意义重大。本研究（1）通过聚焦等离子束实现二维石墨烯微片的显微缺陷加工，通过物理与化学方法在其表面刻蚀缺陷并考察纳米尺寸缺陷对材料力学性能影响，验证经典三维Griffith断裂理论在低维仍然适用。（2）通过石墨烯“缺陷工程”，在石墨烯表面构建可供铁原子、团簇钉扎位点（孔洞、掺杂原子），构建石墨烯负载铁原子为代表的单原子催化剂体系，表现出优异的电催化氧气还原性能。（3）通过调整活性物质前驱体种类（油酸钴），调节热处理升温速率，优化掺杂剂热解释放气体压力，构建石墨烯三维多级孔结构，表现出优异的双功能电催化性质，组装锌空电池表现出优异循环性能。（4）再根据前阶段研究基础，利用氮化碳独特的富氮结构，构筑单原子铁桥接石墨烯/氮化碳电催化剂，表现出优异的氧还原性能。（5）我们通过电解剥离法，在石墨烯表面制备出单分散钴原子催化剂，表现出优异的氧气析出性能。（6）采用同样方法我们还制备出石墨烯负载单分散锌原子催化剂，表现出优异的CO2固定制备碳酸二甲酯活性。综上，本研究通过主动对石墨烯进行缺陷加工，引入以铁原子前驱体为代表的前驱物，构筑石墨烯负载单分散金属原子催化剂，表现出优异的电催化活性。我们利用各先进表征手段，如同步辐射X射线吸收谱，穆斯堡尔谱，球差电镜等，等获得了以M（金属原子）-Nx(掺杂原子)-C为代表的石墨烯/单分散铁原子复合材料微观结构特征，阐明单原子落位的微观化学环境，键合结构，为开发下一代高效、低成本单原子催化剂提供重要的合成制备方法和应用。