Chemical vapor deposition (CVD) growth is regarded as the most promising method for realizing structure-specific single-walled carbon nanotube (SWNT) growth. In the past 20 years, many efforts dedicated to chirality-selective SWNT growth using various strategies have been reported. However, normal CVD growth under constant conditions could not fully optimize the chirality because the randomly formed cap structure allows the nucleation of all types of SWNTs and the chirality of an SWNT is unlikely to be changed during the following elongation process. We report a new CVD process that allows temperature to be periodically changed to vary SWNT chirality multiple times during elongation to build up the energetically preferred SWNT-catalyst interface. With this strategy, SWNTs with small helix angles (less than 10°), which are predicted to have lower interfacial formation energy than others, are enriched up to ~72%. Kinetic analysis of the process suggests a multiple redistribution feature whereby a large chiral angle SWNT tends to reach the near-zigzag chirality step by step with a small chiral angle change at each step, and hence, we named this method "tandem plate CVD." This method opens a door to synthesizing chirality-selective SWNTs by rational catalyst design.

中文翻译：

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具有稳定管-催化剂界面的近曲折单壁碳纳米管的化学气相沉积合成。

化学气相沉积（CVD）生长被认为是实现特定于结构的单壁碳纳米管（SWNT）生长的最有前途的方法。在过去的20年中，已经报道了使用各种策略致力于手性选择性SWNT生长的许多努力。但是，在恒定条件下正常的CVD生长不能完全优化手性，因为随机形成的帽盖结构允许所有类型的SWNT成核，并且在随后的延伸过程中SWNT的手性不太可能改变。我们报告了一种新的CVD工艺，该工艺允许在延伸过程中周期性地改变温度以多次改变SWNT手性，从而建立了能量优先的SWNT-催化剂界面。采用这种策略，螺旋角较小（小于10°）的单壁碳纳米管，预计这些元素的界面形成能比其他元素低，最多可富集约72％。该过程的动力学分析表明具有多重重新分布特征，即大手性角SWNT趋于逐步达到近曲折手性，而每一步手性角变化较小，因此，我们将此方法称为“串联板CVD”。该方法为通过合理的催化剂设计合成手性选择性单壁碳纳米管打开了一扇门。