1] nanotech@surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland [2] Nanotechnology on Surfaces Laboratory, Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Avenida Américo Vespucio 49, E-41092 Sevilla, Spain (J.R.S.-V.); BASF SE, GVM/I-L 544, 67056 Ludwigshafen, Germany (A.M.); University Erlangen-Nuremberg, Institut für Organische Chemie II, Henkestrasse 42, 91054 Erlangen, Germany (K.A.).
nanotech@surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
Nature. 2014 Aug 7;512(7512):61-4. doi: 10.1038/nature13607.
Over the past two decades, single-walled carbon nanotubes (SWCNTs) have received much attention because their extraordinary properties are promising for numerous applications. Many of these properties depend sensitively on SWCNT structure, which is characterized by the chiral index (n,m) that denotes the length and orientation of the circumferential vector in the hexagonal carbon lattice. Electronic properties are particularly strongly affected, with subtle structural changes switching tubes from metallic to semiconducting with various bandgaps. Monodisperse 'single-chirality' (that is, with a single (n,m) index) SWCNTs are thus needed to fully exploit their technological potential. Controlled synthesis through catalyst engineering, end-cap engineering or cloning strategies, and also tube sorting based on chromatography, density-gradient centrifugation, electrophoresis and other techniques, have delivered SWCNT samples with narrow distributions of tube diameter and a large fraction of a predetermined tube type. But an effective pathway to truly monodisperse SWCNTs remains elusive. The use of template molecules to unambiguously dictate the diameter and chirality of the resulting nanotube holds great promise in this regard, but has hitherto had only limited practical success. Here we show that this bottom-up strategy can produce targeted nanotubes: we convert molecular precursors into ultrashort singly capped (6,6) 'armchair' nanotube seeds using surface-catalysed cyclodehydrogenation on a platinum (111) surface, and then elongate these during a subsequent growth phase to produce single-chirality and essentially defect-free SWCNTs with lengths up to a few hundred nanometres. We expect that our on-surface synthesis approach will provide a route to nanotube-based materials with highly optimized properties for applications such as light detectors, photovoltaics, field-effect transistors and sensors.
在过去的二十年中，单壁碳纳米管（SWCNTs）受到了广泛关注，因为它们的非凡性质在许多应用中具有广阔的前景。这些性质中的许多都对 SWCNT 的结构非常敏感，结构由手性指数（n，m）来表示，该指数表示六边形碳晶格中圆周矢量的长度和方向。电子性质尤其受到强烈影响，细微的结构变化将管从金属转变为半导体，同时具有各种带隙。因此，需要单分散“单手性”（即具有单个（n，m）指数）的 SWCNTs 来充分发挥其技术潜力。通过催化剂工程、端帽工程或克隆策略进行的受控合成，以及基于色谱法、密度梯度离心、电泳和其他技术的管分类，已经提供了具有窄管直径分布和大比例预定管类型的 SWCNT 样品。但是，实现真正单分散的 SWCNTs 的有效途径仍然难以捉摸。使用模板分子来明确规定所得纳米管的直径和手性具有很大的潜力，但迄今为止，实际应用的成功有限。在这里，我们表明这种自下而上的策略可以产生靶向纳米管：我们使用表面催化的环脱氢反应，在铂（111）表面上将分子前体转化为超短单封端（6,6）“扶手椅”纳米管种子，然后在随后的生长阶段中延长这些种子，以产生单手性和本质上无缺陷的 SWCNTs，长度可达数百纳米。我们预计，我们的表面合成方法将为基于纳米管的材料提供一种途径，这些材料具有高度优化的性质，可用于光探测器、光伏、场效应晶体管和传感器等应用。
