可控合成一维线性碳链及其生长机理研究

The carbon element has a variety of allotropes, and their structures are from three-dimensional, two-dimensional to one-dimensional, whereas their electrical conductivities are from conductor, semiconductor to insulator. At present, the research on allotropes of carbon is mainly concentrated in three-dimensional and two-dimensional structures, and the research on one-dimensional structure is still lacking. Theoretical calculations show that one-dimensional chain-like carbon, i.e. one-dimensional linear carbon chain, has higher mechanical strength and superior photoelectric performance than three-dimensional diamond and two-dimensional graphene. Therefore, the pioneering fundamental research on the one-dimensional linear carbon chain will help to develop distinctive frontier fundamental research fields and make ground-breaking research results. Recently, we have developed a ultra-high-temperature high-vacuum templated method to prepare the world's longest one-dimensional linear carbon chain. However, the lengths of the chains are still uncontrollable, the yield is low, and the growth mechanism is not clear. This project aims to design and synthesize a series of one-dimensional linear carbon chains with controllable length and greatly improved yield. Based on those experiments, combined with theoretical study, the growth mechanism of one-dimensional linear carbon chains will be proposed and verified. Those knowledges could improve the synthesis of even longer one-dimensional linear carbon chains; thus, we can adjust the band gap of one-dimensional linear carbon chains to somewhere close to the band gap of silicon, which would be helpful to the future application research. This project is a cutting-edge fundamental research that will enrich people's understanding of carbon nanomaterials and has important academic significance.

碳单质拥有多种同素异形体，结构从三维、二维到一维；导电性能则从导体、半导体到绝缘体。目前对于碳的同素异形体的研究主要集中在三维和二维方向，对于一维结构的研究还处于起步阶段。理论计算表明一维的链状碳，即一维线性碳链，比三维结构的金刚石和二维结构的石墨烯有更高的力学强度以及更优越的光电性能。因此，对于一维线性碳链进行先导性的基础研究，有助于发展出有特色的前沿基础研究领域，作出开创性的研究成果。近期我们利用一种超高温高真空模板法制备出了世界上最长的一维线性碳链，然而其制备长度尚不可控、产率较低、生长机理不明确。本项目旨在设计合成一系列长度可控的一维线性碳链，极大地提高其产率；以实验为基础，与理论相结合，提出并验证一维线性碳链的生长机理，并以此为指导合成更长的一维线性碳链，调整其带隙到和硅相近的位置，为将来的应用研究做准备。本项目为前沿基础研究，将丰富人们对于碳纳米材料的认知，有着重要的学术意义。

线性碳链是唯一一种一维结构的sp电子轨道杂化的碳的同素异形体，理论预言具有优于三维金刚石、二维石墨烯和准一维碳纳米管的光学、电学和力学性质，因此近期受到了极大的关注。本项目为了解决超高温高真空模板法制备的一维线性碳链的长度不可控、产率较低、生长机理不明确等实际问题，设计了系列实验进行验证，通过控制碳纳米管模板的直径来调控合成线性碳链的长度及性能；通过引入额外碳源来提高合成产率；通过同位素标记来研究生长机理。具体而言，合成了长度可控的一维线性碳链，并通过碳纳米管的直径来控制与一维线性碳链之间相互作用的大小，从而最终实现了一维线性碳链的带隙可在1.8到2.3电子伏特之间调节；首次合成同位素标记的一维线性碳链，并连续两次提高同位素标记含量的世界记录，最终达到了28.8%；探索了利用激光加热来原位合成一维线性碳链，为定点引入一维线性碳链提供了可行的技术；厘清了压强与一维线性碳链生长之间的关系，发现无需高真空即可实现一维线性碳链的高效制备，为今后一维线性碳链的大规模制备提供了指引；利用共振拉曼光谱和时间分辨拉曼光谱研究了一维线性碳链的带隙分布、一维线性碳链与碳纳米管之间的电荷与能量转移、一维线性碳链的生长机理。通过本项目的实施，使我们有能力提供高产率、高稳定性、高均一性、可同位素标记的一维线性碳链样品，有助于未来对一维线性碳链的优异性质和实际应用进行进一步的研究，有望产出实用的高导热、导电并具有优异力学性能的产品。