Department of Chemical System Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
ACS Nano. 2011 Feb 22;5(2):975-84. doi: 10.1021/nn102380j. Epub 2011 Jan 4.
Millimeter-tall vertically aligned single-walled carbon nanotubes (SWCNTs) were grown in 10-15 min by chemical vapor deposition from C(2)H(2)/Ar with or without water addition using Fe catalyst supported on an Al-Si-O underlayer. Using combinatorial catalyst libraries coupled with the real-time monitoring of SWCNT growth, the catalyst and chemical vapor deposition conditions were systematically examined, and millimeter-tall SWCNTs were obtained even without water addition. The key for millimeter-scale growth of SWCNTs is to limit the C(2)H(2) supply to below a certain partial pressure to retain an active catalyst. Water prolongs the catalyst lifetime under excess C(2)H(2) supply, whereas it deactivates small catalyst particles and degrades the quality of SWCNTs at the same time. We also observed a gradual increase in the diameter of SWCNTs with growth because of the coarsening of catalyst particles and found that water had no effect on this phenomenon. We demonstrate millimeter-tall SWCNTs grown by simply using C(2)H(2)/Ar gas without water addition, which revealed the mysterious role of water, and we show a practical route for the large-scale production of SWCNTs.
在 Al-Si-O 底层负载 Fe 催化剂的条件下，通过 C(2)H(2)/Ar 化学气相沉积，在 10-15 分钟内可生长出毫微米级的垂直排列单壁碳纳米管（SWCNTs），无需添加水。采用组合催化剂库并实时监测 SWCNT 的生长，可以系统地检查催化剂和化学气相沉积条件，即使不添加水也可以获得毫微米级的 SWCNTs。SWCNTs 毫米级生长的关键是将 C(2)H(2)的供应量限制在一定的分压以下，以保持催化剂的活性。水在过量 C(2)H(2)供应下延长了催化剂的寿命，但同时也会使小催化剂颗粒失活，并降低 SWCNTs 的质量。我们还观察到，随着生长的进行，SWCNTs 的直径逐渐增大，这是由于催化剂颗粒的粗化所致，并且发现水对此现象没有影响。我们展示了一种简单地使用 C(2)H(2)/Ar 气体而无需添加水就可以生长出毫微米级的 SWCNTs 的方法，揭示了水的神秘作用，并展示了大规模生产 SWCNTs 的实用途径。
