Conceptually, carbon nanotubes are one-dimensional tubular molecules formed by the curling of graphene and have excellent mechanical and thermal properties as well as high carrier mobility. Graphene also exhibits structurally tunable electrons, The optoelectronic properties have an important application prospect in building the next generation of high-speed, low-power, highly integrated electronic and optoelectronic integrated circuits.However, the properties of carbon nanotubes are determined by their structure.The small differences in atomic arrangement will lead to their properties Therefore, the control of the structure of carbon nanotubes is the premise of its nature and application of research, but also the hot and difficult nano-science and technology research field.
Research Institute of Physics, Chinese Academy of Sciences / Advanced Material and Structure Analysis Laboratory, State Key Laboratory of Condensed Matter Physics, Beijing A05 researcher Liu Huaping devoted to the separation and development of carbon nanotube structure. Gel chromatography is used to realize a variety of single chiral carbons with diameter less than 1 nm In recent years, through the synergistic effect of temperature, ethanol and various surfactant molecules, the interaction between different helical structures of carbon nanotubes and gels has been regulated at the molecular scale, On the basis of this, based on the specific luminescence and photo-electric response properties of chirally-enriched carbon nanotubes prepared by separation, we cooperated with Professor Peng Lian-mao from Peking University to build the first two-dimensional and three-dimensional However, currently, the diameters of carbon nanotubes prepared by gel permeation chromatography are less than 1 nm, and the separation of single-walled carbon nanotubes larger than 1.2 nm in diameter has been a worldwide problem.As the diameter of carbon nanotubes , The types of carbon nanotubes with the same diameter increase, and the difficulty in the separation of carbon nanotube structures continues to increase. However, theoretical research It shows that the application in terms of high-performance transistors, the optimum diameter range of semiconducting carbon nanotubes is 1.2-1.7nm.
Recently, Yang Dehua, Hu Jinwen, researcher Liu Huaping, researcher Liu Huaping and Zhou Weiya, graduate students in the research group, used NaOH to control the adsorption of surfactant molecules on the surface of carbon nanotubes, expanding the interaction between large-diameter carbon nanotubes and polysaccharide gels The structural separation of large-diameter carbon nanotubes (> 1.2 nm in diameter) can be achieved. The chiral purity of the prepared semiconducting carbon nanotubes can be as high as nearly 40%, and the purity of semiconductors can be higher than 99%. Optical characterization verifies that the above- Experimental results (Figure 1-3) This method inherits the advantages of simple, fast, low-cost and easy-to-scale separation of carbon nanotubes by gel permeation chromatography.The separation yield can be as high as milligram by process optimization. The results provide material support for the preparation of high performance large area carbon nanotube integrated electronic devices and infrared optoelectronic devices, which laid the foundation for the further separation of single chiral large diameter semiconducting carbon nanotubes.
Research has been supported by the National Natural Science Foundation of China, the CAS Key Research Program of Frontier Science, the "Youth Thousands" Program of the Central Organization Department and the "Hundred Talents Program" of the Chinese Academy of Sciences.
Figure 1. Optical photographs of separately prepared aqueous solutions of different structures of carbon nanotubes. (A) Solution of microgram-sized carbon nanotubes isolated; (b) After optimization of the process parameters, the macroscopically separated solution of carbon nanotubes The content of carbon nanotubes in each bottle of dispersion).
Figure 2. Spectral characterization of separately prepared carbon nanotube solutions. (A) Characterization by light absorption; (b) Raman spectroscopy (excitation at 514 nm).
Figure 3. Purity evaluation of separately prepared carbon nanotubes. (A) Chiral purity evaluation, the chiral purity of the prepared carbon nanotubes can be calculated by peak-fitting calculation up to nearly 40%; (b) Evaluation of semiconductor purity, separation The purity of the prepared carbon nanotube semiconductor can be up to over 99% (calculated from the area ratio of the absorption peak of S22 semiconductor to the absorption peak of metal tube M11).
