The role of hydrogen in the aerosol-assisted chemical vapor deposition process in producing thin and densely packed vertically aligned carbon nanotubes
The role of hydrogen in the aerosol-assisted chemical vapor deposition process in producing thin and densely packed vertically aligned carbon nanotubes
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DOI：
10.1016/j.carbon.2013.05.040
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发表时间：
2013-09-01
期刊：
影响因子：
10.9
通讯作者：
Mayne-L'Hermite, Martine
中科院分区：
文献类型：
--
作者：
Castro, Celia;Pinault, Mathieu;Mayne-L'Hermite, Martine
气溶胶辅助催化化学气相沉积（CCVD）是一种由二茂铁和甲苯前驱体合成垂直排列碳纳米管（VACNT）阵列的高效单步工艺。虽然不需要促进剂，但向载气中加入氢有助于这一过程。为了了解氢的作用，我们分别在850℃和800℃下进行了合成。通过电子显微镜分析了产物沿反应器长度的分布，以跟踪氢的影响，以及碳纳米管和催化剂纳米颗粒的特性。随着氢含量的增加，碳纳米管生长向炉口方向移动，碳纳米管直径明显减小，碳纳米管数量密度增加。氢通过降低二茂铁的分解温度和增加催化纳米粒子的成核位密度，明显地影响了气相现象。在气溶胶辅助CCVD工艺中，氢气条件下的产率仍然合理，甚至在800℃时也有所提高。氢含量似乎是控制垂直排列碳纳米管特性的一个有趣参数。(C) 2013 Elsevier Ltd.版权所有。
Aerosol-assisted catalytic chemical vapor deposition (CCVD) is an efficient single-step process to synthesize vertically aligned carbon nanotube (VACNT) arrays from ferrocene and toluene precursors. While no promoters are needed, adding hydrogen to the carrier gas assists the process. In order to understand the role of hydrogen, we performed syntheses at 850 and 800 degrees C. The product distribution along the length of the reactor was analyzed by electron microscopy to follow the effect of the hydrogen, as well as the characteristics of the CNT and catalyst nanopartides. Increasing the hydrogen content shifts the CNT growth towards the furnace entrance and strongly reduces the CNT diameters, while the CNT number density increases. Hydrogen demonstrably affects the gas phase phenomena by lowering the decomposition temperature of ferrocene and increasing the nucleation site density of the catalytic nanopartides. The yield under hydrogen remains reasonable in the aerosol-assisted CCVD process, and is even improved at 800 degrees C. Hydrogen content appears to be an interesting parameter to control the characteristics of vertically aligned CNT. (C) 2013 Elsevier Ltd. All rights reserved.