Prof. USTC Yushu Hong TF prepared superelastic fatigue hard carbon airgel

Carbon material may be hybrid orbitals of carbon atoms divided into graphitic carbon (GC), soft carbon (SC) and hard carbon (HC). Carbon graphite long-range ordered structure having a two-dimensional hexagonal crystals, such as graphite, graphite alkynyl, graphene oxide / graphene, carbon nanotubes. In the pyrolysis process, some of the carbon atoms constituting the two-dimensional heavy aromatic graphene sheet, if the graphene sheet is substantially parallel, it is easy graphitization at a high temperature, referred to as soft carbon; if random graphene sheets stacked and the edge crosslinked atoms, not graphitized at a high temperature, is called hard carbon. In general, carbon and graphite, soft carbon having high elasticity, but lower strength, easily deformed, and the strength of the hard carbon, good stability, but brittle. How hard carbon material is prepared as a superelastic material block is still a challenge. Recently, the Department of Chemistry, USTC research group led by Prof. Yushu Hong spider web of nature while having high strength and elasticity of inspiration, build nano-fiber network structure by clever template method, given the traditional hard carbon super-elastic material. By the use of resorcinol – formaldehyde (RF) resin as a hard carbon, a variety of 1D nanofibers, including bacterial cellulose nanofiber (the BCNF), tellurium nanowires (TeNW) and carbon nanotubes (CNT) as a template structure RF aerogels prepared nanofibers, can be obtained by high temperature carbonization superelastic and fatigue hard carbon airgel (HCA). Researchers simple control the ratio of raw materials, can be regulated easily achieved airgel physical parameters, such as fiber diameter and density. structural stability weld between the hard carbon nanofiber thanks to the network structure and fiber, resulting HCAs have excellent mechanical properties. As it can be seen by in situ scanning electron microscope, after 50% compression, the overall structure of the material restitution, and no obvious structural damage or irreversible deformation. superelastic The material has excellent elastic properties, rebound velocity of up to 860 mm s-1, low energy loss factor 0.16, as compared with conventional carbon material, both flexibility and strength. The new HCA achieves a balance between flexibility and strength, the researchers explored the properties related to its large range as piezoresistive sensors, and stretchable / bendable conductor. The results show that the resilient conductor has an excellent cycle stability, and because of the structureAnd stability of the composition, the work can be achieved (e.g., liquid nitrogen) under harsh conditions. The greatest significance of this study is, through inspiration and microstructure of the designed natural materials, can be converted to a conventional resin brittle performance rigid superelastic material is hard carbon airgel, a carbon material relative to conventional ratio, the airgel has a very high rebound velocity, low energy consumption, while maintaining high strength and stability. This method is expected to be extended to the preparation of other non-carbon-based fibrous materials, and provide a new idea by nanofibers microstructure design to transform the material into a rigid or flexible elastomeric material. References: Zhi-Long Yu, BingQin, Zhi-Yuan Ma, Jin Huang, Si-Cheng Li, Hao-Yu Zhao, Han Li, Yin-Bo Zhu, Heng-An Wu, and Shu-Hong Yu *, Superelastic Hard Carbon Nanofiber Aerogels, Adv.Mater.2019,1900651