State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics & Tsinghua-Foxconn Nanotechnology Research Center, Collaborative Innovation Center of Quantum Matter, Tsinghua University , Beijing 100084, China.
Fert Beijing Research Institute, School of Electrical and Information Engineering, BDBC, Beihang University , Beijing 100191, China.
ACS Nano. 2017 Feb 28;11(2):1257-1263. doi: 10.1021/acsnano.6b04855. Epub 2017 Feb 14.
Exploiting the superior properties of nanomaterials at macroscopic scale is a key issue of nanoscience. Different from the integration strategy, "additive synthesis" of macroscopic structures from nanomaterial templates may be a promising choice. In this paper, we report the epitaxial growth of aligned, continuous, and catalyst-free carbon nanofiber thin films from carbon nanotube films. The fabrication process includes thickening of continuous carbon nanotube films by gas-phase pyrolytic carbon deposition and further graphitization of the carbon layer by high-temperature treatment. As-fabricated nanofibers in the film have an "annual ring" cross-section, with a carbon nanotube core and a graphitic periphery, indicating the templated growth mechanism. The absence of a distinct interface between the carbon nanotube template and the graphitic periphery further implies the epitaxial growth mechanism of the fiber. The mechanically robust thin film with tunable fiber diameters from tens of nanometers to several micrometers possesses low density, high electrical conductivity, and high thermal conductivity. Further extension of this fabrication method to enhance carbon nanotube yarns is also demonstrated, resulting in yarns with ∼4-fold increased tensile strength and ∼10-fold increased Young's modulus. The aligned and continuous features of the films together with their outstanding physical and chemical properties would certainly promote the large-scale applications of carbon nanofibers.
在宏观尺度上开发纳米材料的优越性能是纳米科学的一个关键问题。与集成策略不同，从纳米材料模板“添加合成”宏观结构可能是一个有前途的选择。在本文中，我们报告了从碳纳米管薄膜外延生长取向、连续、无催化剂的碳纤维薄膜。该制造工艺包括气相热解碳沉积使连续碳纳米管薄膜增厚，以及高温处理使碳层进一步石墨化。所制备的纤维在薄膜中具有“年轮”截面，具有碳纳米管核和石墨外围，表明其模板生长机制。碳纳米管模板和石墨外围之间没有明显的界面进一步表明了纤维的外延生长机制。这种机械强度高的薄膜具有从几十纳米到几微米可调的纤维直径，具有低密度、高导电性和高热导率。还进一步展示了将这种制造方法扩展到增强碳纳米管纱线，得到的纱线拉伸强度提高了约 4 倍，杨氏模量提高了约 10 倍。该薄膜具有取向和连续的特点以及其优异的物理和化学性能，必将促进碳纤维的大规模应用。
