Study of precise on structural control of carbon nanotubes

针对单晶衬底上CVD生长单壁碳纳米管的问题，以铁蛋白为生长催化剂，探讨了蓝宝石衬底上自定向生长单壁碳纳米管的机理。我们对在特殊设计的衬底上生长行为的分析表明，定向生长是由尖端生长机制引起的。通过对蓝宝石衬底上单壁碳纳米管生长的原位SEM观察证实了这一结论。通过使用拉曼光谱原位观察CVD生长过程，研究了单壁碳纳米管的手征分辨生长动力学。首次清晰地检测到了单壁碳纳米管径向呼吸模式的拉曼信号。我们的生长动力学的详细分析澄清了单壁碳纳米管的手性，催化剂直径和growth duration之间的相关性。单壁碳纳米管生长在非常干净的条件下，在一个UHV兼容的气源MBE系统，使用酒精作为碳原料。生长的单壁碳纳米管的化学状态是特征性的 ...更多信息 通过原位X射线光电子能谱进行了表征。从光谱的分析中，我们发现Co催化剂颗粒甚至在CVD生长后仍保持“金属态”，与普通的VLS生长机制相反，并且Fe催化剂在较高温度下CVD生长后部分形成氧化物，这解释了与Co催化剂相比，Fe催化剂的SWCNT产率非常低。（直径小于2nm）通过蒸发衍生自铁蛋白的颗粒（直径为3-5 nm，刚煅烧后）来制备。通过单壁碳纳米管直径与催化剂颗粒之间的相关性，提出了单壁碳纳米管直径控制的可能性。单壁碳纳米管是由新型催化剂材料合成的，这些催化剂材料被认为没有催化活性，例如半导体纳米颗粒Si、Ge、SiC和贵金属纳米颗粒金、银、铜。基于这些现象，我们提出了一种新的生长机制，这将打开手性控制的可能性。少

For the CVD growth of single-walled carbon nanotubes(SWCNTs) on crystalline substrates, the mechanism of self-directional growth on sapphire substrates was explored by using ferritins as growth catalysts. Our analysis of growth behavior on the specially designed substrates indicates that the directional growth is caused by the tip-growth mechanism. This conclusion was confirmed by in-situ SEM observation of the SWCNT growth on sapphire substrates. Chirality-resolved growth kinetics of SWCNTs was investigated by in situ observation of the CVD growth process using Raman spectroscopy. The Raman signals of radial breathing modes from growing SWCNTs were clearly detected for the first time. Our detailed analysis of the growth kinetics clarified the correlation among SWCNT chirality, catalyst diameter and growth duration.SWCNTs were grown under very clean conditions in a UHV-compatible gas-source MBE system using alcohol as carbon feedstock. The chemical states of grown SWCNTs were character … More ized by in-situ X-ray photoelectron spectroscopy. From the analysis of the spectra, we found that Co catalyst particles maintain "metallic states" even after CVD growth, contrary to the ordinary VLS growth mechanism, and that Fe catalysts partially form oxides after CVD growth at higher temperature, which explains the very low yield of SWCNTs for Fe catalyst compared with Co catalyst.Very fine metal nanoparticles(diameter of less than 2 nm) were prepared by evaporation of particles(diameter of 3-5 nm, just after calcination) derived from ferritin. The possibility of SWCNT diameter control is suggested by the correlation between diameters of SWCNTs and the catalyst particles. SWCNTs were synthesized from novel catalyst materials, which have been considered to have no catalytic activity, such as semiconductor nanoparticles of Si, Ge, SiC, and noble metal nanoparticles of gold, silver, copper. On basis of these phenomena, we proposed a new growth mechanism that will open up the possibility of chirality control. Less