钴合金亚纳米催化相控制生长亚纳米直径的单壁碳纳米管

A major bottleneck for the application of single-walled carbon nanotubes (SWCNTs) in nano-electronics is that the current synthesis methods produce SWCNTs with different chiralities, leading to mixtures of metallic and semiconducting nanotubes. In this application, the secondary phase of Cr or Nb in the Co-based binary alloy would be used to decrease the size of Co phase to sub-nanometer scale, and to stabilize the sub-nanometer catalytic Co phase by forming non-catalytic phase of Cr or Nb derived carbides. Furthermore, a remote thermal chemical vapor deposition (RTCVD) method would be used to lower the growth temperature of SWCNTs, avoiding the agglomeration and growing of the Co alloy catalyst. SWCNTs with sub-nanometer diameter would be synthesized by optimizing the structure of the Co phase and the thermodynamic and kinetic parameters for SWCNT. We will investigate the formation, optimization and stabilization of the sub-nanometer catalytic Co phase in the Co alloy. The effect of size, morphology and crystal structure of the Co sub-nanometer catalytic phase on the diameter and chirality of the SWCNTs would be investigated. Our objective is to establish the relationship between the Co-based binary alloy catalyst and the structure and transport proerpty of the SWCNTs obtained, to reveal the SWCNT growth mechanism, and to establish an efficient method for the growth of SWCNTs with sub-nanometer diameter. The feasibility of this method for the controlled growth of SWCNTs with specific electronic types would be explored, and the fundamentals and routes for the controlled growth of SWCNTs with specific electronic types would be provided.

针对单壁碳纳米管（简称碳管）导电属性控制这一制约其基础研究与实际应用的"瓶颈"问题，利用Co基双相合金中的Cr或Nb第二相细化Co基体相尺寸至亚纳米量级，再利用Cr、Nb碳化物稳定Co亚纳米催化相，采用远端热增强CVD法，降低制备温度，避免Co基双相合金纳米催化剂颗粒的团聚与长大，通过优化Co相的结构和碳管生长的热力学和动力学条件，实现碳管由Co亚纳米催化相的形核长大，控制生长出窄直径与手性分布的亚纳米直径碳管。研究Co合金催化剂颗粒中Co亚纳米催化相的结构形成、优化和稳定机制，研究Co催化相尺寸、形貌及晶体结构对碳管直径、直径分布及手性的影响，建立Co基双相合金催化剂与碳管的结构关系，揭示Co亚纳米催化相控制生长碳管的机理，建立Co基双相合金催化剂控制生长窄直径与手性分布、小直径碳管的方法，探索该方法对控制碳管导电属性的可行性，为实现碳管导电属性的有效控制奠定基础与探索途径。

针对单壁碳纳米管（碳管）导电属性控制这一制约其基础研究与实际应用的“瓶颈”问题，利用Co基双相合金中的C、Ta或Ru第二相细化Co催化相尺寸至亚纳米量级，再利用碳层、Ta或Ru碳化物稳定Co催化相结构，设计了部分碳包覆Co纳米颗粒催化剂、Co/Ta和Co/Ru双金属纳米颗粒催化剂，改进传嵌段共聚物自组装法和表面担载法，分别制备出尺寸均一、成分可调的催化剂，再通过优化Co催化相的结构和碳管生长的热力学和动力学条件，控制生长出窄直径与手性分布、单一导电属性（包括亚纳米直径且更为优异）碳管。研究了Co合金催化剂颗粒中Co催化相的结构形成、优化和稳定机制，研究了Co催化相尺寸、形貌及晶体结构对碳管直径分布、导电属性及手性的影响，揭示出亚纳米催化相控制的“非自发形核与切线生长”亚纳米直径碳管生长机理。在此基础上，探索了碳管在场效应晶体管等电子器件和氧还原等电化学器件上的应用。研究成果在Nature Communications, Adv. Mater, J. Phys. Chem. Lett., Carbon等国际著名专业刊物发表7篇，培养博士生5名，其中，4名已毕业，一名博士毕业生入选中科院百人计划。