Aix Marseille Université, CNRS, Centre Interdisciplinaire de Nanoscience de Marseille, Campus de Luminy, Case 913, F-13288 Marseille, France.
Laboratoire d'Etude des Microstructures, ONERA-CNRS, UMR104, Université Paris-Saclay, BP 72, 92322 Châtillon Cedex, France.
Science. 2018 Oct 12;362(6411):212-215. doi: 10.1126/science.aat6228.
Single-walled carbon nanotubes are hollow cylinders that can grow centimeters long via carbon incorporation at the interface with a catalyst. They display semiconducting or metallic characteristics, depending on their helicity, which is determined during their growth. To support the quest for a selective synthesis, we develop a thermodynamic model that relates the tube-catalyst interfacial energies, temperature, and the resulting tube chirality. We show that nanotubes can grow chiral because of the configurational entropy of their nanometer-sized edge, thus explaining experimentally observed temperature evolutions of chiral distributions. Taking the chemical nature of the catalyst into account through interfacial energies, we derive structural maps and phase diagrams that will guide a rational choice of a catalyst and growth parameters toward a better selectivity.
单壁碳纳米管是一种中空的圆柱体，通过在与催化剂的界面处掺入碳，可以生长数厘米长。它们表现出半导体或金属特性，这取决于它们的螺旋性，螺旋性在生长过程中确定。为了支持选择性合成的研究，我们开发了一种热力学模型，该模型将管-催化剂界面能、温度以及由此产生的管手性联系起来。我们表明，由于其纳米级边缘的构象熵，纳米管可以生长手性，从而解释了实验观察到的手性分布的温度演化。通过界面能考虑催化剂的化学性质，我们得出了结构图谱和相图，这些图谱将指导催化剂和生长参数的合理选择，以提高选择性。
