Li Han, Gordeev Georgy, Wasserroth Sören, Chakravadhanula Venkata Sai Kiran, Neelakandhan Shyam Kumar Chethala, Hennrich Frank, Jorio Ado, Reich Stephanie, Krupke Ralph, Flavel Benjamin Scott
Institute of Nanotechnology, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany.
Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany.
Nat Nanotechnol. 2017 Dec;12(12):1176-1182. doi: 10.1038/nnano.2017.207. Epub 2017 Oct 2.
Double-walled carbon nanotubes (DWCNTs) consist of two coaxially aligned single-walled carbon nanotubes (SWCNTs), and previous sorting methods only achieved outer-wall electronic-type selectivity. Here, a separation technique capable of sorting DWCNTs by semiconducting (S) or metallic (M) inner- and outer-wall electronic type is presented. Electronic coupling between the inner and outer wall is used to alter the surfactant coating around each of the DWCNT types, and aqueous gel permeation is used to separate them. Aqueous methods are used to remove SWCNT species from the raw material and prepare enriched DWCNT fractions. The enriched DWCNT fractions are then transferred into either chlorobenzene or toluene using the copolymer PFO-BPy to yield the four inner@outer combinations of M@M, M@S, S@M and S@S. The high purity of the resulting fractions is verified by absorption measurements, transmission electron microscopy, atomic force microscopy, resonance Raman mapping and high-density field-effect transistor devices.
双壁碳纳米管（DWCNT）由两个同轴排列的单壁碳纳米管（SWCNT）组成，而之前的分选方法仅实现了外壁电子类型的选择性。在此，提出了一种能够根据半导体（S）或金属（M）内壁和外壁电子类型对双壁碳纳米管进行分选的分离技术。利用内壁和外壁之间的电子耦合来改变每种双壁碳纳米管类型周围的表面活性剂涂层，并使用水性凝胶渗透法对其进行分离。采用水相方法从原料中去除单壁碳纳米管物种并制备富集的双壁碳纳米管级分。然后使用共聚物PFO-BPy将富集的双壁碳纳米管级分转移到氯苯或甲苯中，以得到M@M、M@S、S@M和S@S这四种内壁@外壁组合。通过吸收测量、透射电子显微镜、原子力显微镜、共振拉曼映射和高密度场效应晶体管器件验证了所得级分的高纯度。
