Sub-nanometer armchair graphene nanoribbons (GNRs) with moderate band gap have great potential towards novel nanodevices. GNRs can be synthesized in the confined tubular space of single-walled carbon nanotubes (SWCNTs), in which precursor molecules have been specifically designed to form the GNRs with certain width and edge. However, it is still unexplored how the diameter and metallicity of SWCNTs influence the synthesis of the GNRs. Herein, we applied a series of SWCNTs with different average diameters to study the diameter-dependent synthesis of GNRs. By using Raman spectroscopy and transmission electron microscopy, we found that the width of the GNRs can be tailored by the diameter of the SWCNTs. Especially, the SWCNTs with average diameter of 1.3 nm produced 6 and 7 armchair GNRs with the highest yield, which can be well explained by considering the width of the GNRs and van der Waals radius of hydrogen and carbon atoms. In addition, semiconducting and metallic SWCNTs produced GNRs with different yields, which could attribute to different diameter distributions and density of defects. These results enable the possibility of a high-yield production of certain armchair graphene nanoribbons in large scale, which would benefit future applications as semiconductor with sub-nanometer in width.

具有中等带隙的亚纳米扶手椅石墨烯纳米带（GNR）在新型纳米器件方面具有巨大潜力。GNRs 可以在单壁碳纳米管 (SWCNTs) 的受限管状空间中合成，其中前体分子经过专门设计以形成具有一定宽度和边缘的 GNRs。然而，SWCNTs 的直径和金属丰度如何影响 GNRs 的合成仍然是未知的。在这里，我们应用了一系列具有不同平均直径的 SWCNT 来研究 GNR 的直径依赖性合成。通过使用拉曼光谱和透射电子显微镜，我们发现 GNR 的宽度可以通过 SWCNT 的直径进行调整。特别是，平均直径为 1.3 nm 的 SWCNTs 产生了 6 和 7 个扶手椅 GNR，产量最高，这可以通过考虑 GNR 的宽度和氢和碳原子的范德华半径来很好地解释。此外，半导体和金属单壁碳纳米管产生的 GNR 具有不同的产量，这可能归因于不同的直径分布和缺陷密度。这些结果使大规模生产某些扶手椅式石墨烯纳米带成为可能，这将有利于未来作为亚纳米宽度半导体的应用。