Efficient growth of vertically-aligned single-walled carbon nanotubes with combining two unfavorable synthesis conditions
Efficient growth of vertically-aligned single-walled carbon nanotubes with combining two unfavorable synthesis conditions
复制标题
结合两种不利合成条件高效生长垂直排列单壁碳纳米管
DOI：
10.1016/j.carbon.2019.01.109
复制
发表时间：
2019
期刊：
影响因子：
10.9
通讯作者：
Maruyama Shigeo
中科院分区：
文献类型：
--
作者：
Liu Ming;An Hua;Kumamoto Akihito;Inoue Taiki;Chiashi Shohei;Xiang Rong;Maruyama Shigeo
我们展示了一种意想不到的配方，可以有效地合成垂直排列的单壁碳纳米管(SWCNTs)。高密度阵列的生长是通过结合两种不利条件来实现的：低温和单金属钴催化剂，这两种条件都不能有效地合成单壁碳纳米管森林。新配方的结果是，合成的单壁碳纳米管的直径分布比以前的研究结果更窄，85%的单壁碳纳米管的直径在1.6-2.4 nm之间。同时，我们利用我们最近建立的透射电子显微镜技术直接在SiO_2上表征了这种单金属钴催化剂。在600 °C的反应中，纳米颗粒被证实比高温下形成的纳米颗粒更小、更致密、更均匀。我们的技术进一步允许在高温下对催化剂进行成像，从而在单个颗粒水平上可视化Ostwald成熟过程。此外，现场电子衍射法和成像法也证实了单金属钴催化剂在800 °C时仍然是固相的。新生长配方的发现增加了碳纳米管在其他基质上的相容性。新的透射电子显微镜技术为一些长期存在的催化粒子假说提供了实验证据，并能够指导新催化剂的设计。
We demonstrate an unexpected recipe for the efficient synthesis of vertically-aligned single-walled carbon nanotubes (SWCNTs). The growth of high-density arrays is achieved by combining two unfavorable conditions: low temperature and mono-metallic Co catalyst, neither of which was previously found to be effective for the synthesis of SWCNT forest. As a result of this new recipe, the as-synthesized SWCNTs have a narrower diameter distribution than those obtained in previous studies, with 85% of the SWCNTs between 1.6 and 2.4 nm. Meanwhile, we utilize our recently established transmission electron microscopy (TEM) technique to characterize this monometallic Co catalyst directly on SiO2. Nanoparticles in a 600 °C reaction are confirmed to be smaller, denser and more uniform than those formed at high temperatures. Our technique further allows to image catalyst at high temperatures, by which Ostwald ripening is visualized at a single particle level. In addition,in situelectron diffraction and imaging confirm that monometallic Co catalyst remains as a solid phase even at 800 °C. The discovery of new growth recipe increases the compatibility of synthesizing SWCNT onto other substrates. The new TEM technique provides experimental evidence for some long-standing hypotheses of catalytic particles and is capable of guiding the design of new catalysts.