Decoupling Catalyst Dewetting, Gas Decomposition, and Surface Reactions in Carbon Nanotube Forest Growth Reveals Dependence of Density on Nucleation Temperature
Decoupling Catalyst Dewetting, Gas Decomposition, and Surface Reactions in Carbon Nanotube Forest Growth Reveals Dependence of Density on Nucleation Temperature
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DOI：
10.1021/acs.jpcc.9b07894
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
Jaegeun Lee;Moataz Abdulhafez;M. Bedewy
中科院分区：
文献类型：
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作者：
Jaegeun Lee;Moataz Abdulhafez;M. Bedewy
在垂直排列的碳纳米管的化学气相沉积(CVD)中，以下三个过程的温度通常是耦合的：(1)薄膜脱湿形成催化剂纳米颗粒；(2)气体前体的热分解；(3)碳纳米管的成核/生长。在这里，我们提出了一种使用定制设计的多区快速热CVD反应器来完全解耦这些过程的方法。结果表明，在不耦合生长条件下，碳纳米管的密度与成核温度成反比，而与催化剂形成温度无关。重要的是，产生最定向和最致密碳纳米管的成核/生长温度低于产生最高碳纳米管的温度。我们还发现，这种密度的反比关系并不是由于催化剂纳米颗粒的数密度减少，而是由于在较高成核温度下活性催化剂的百分比显着下降所致。一个.。
In chemical vapor deposition (CVD) of vertically aligned carbon nanotubes (CNTs), the temperatures for the following three processes are typically coupled: (1) catalyst nanoparticle formation by film dewetting, (2) thermal decomposition of gas precursors, and (3) nucleation/growth of CNTs. Here, we present an approach for complete decoupling of these processes using a custom-designed multizone rapid thermal CVD reactor. We show that in decoupled growth, there is an inverse relationship between the density of CNTs and nucleation temperature, while there is no dependence of density on the catalyst formation temperature. Importantly, the nucleation/growth temperature that produces the most aligned and densest CNTs is lower than the temperature that produces the tallest CNTs. We also reveal that this inverse relation of density is not because of a decreased number density of catalyst nanoparticles but is rather caused by a marked decrease in the percentage of active catalyst at high nucleation temperatures. A...