基于双金属Mo-Fe催化剂调控碳纳米管阵列生长

Controllable morphological modulation of carbon nanotube array by using Mo-Fe bimetallic catalysts

化学气相沉积是制备碳纳米管阵列最常用的方法。催化剂作为碳纳米管生长的模板,通过改变催化剂粒子结构来调控阵列结构是生长碳纳米管阵列的一项重要手段。单金属Fe催化剂是碳管阵列生长最常用的催化剂,但单金属催化剂调控困难,而双金属催化剂具有组分可调、工艺简单、易放大等优势,在碳纳米管阵列结构调控方面展现出了潜在的优势。通过设计碳管生长的催化剂,在原先单金属Fe的基础上加入金属Mo并且改变金属Mo的比例可以有效地控制最终催化剂粒子的尺寸与直径分布,从而实现对阵列的堆积密度、取向性、碳管的壁数与质量等的调控。将催化剂粒子尺寸与直径分布的改变归结为金属Mo对Fe催化剂的"调控作用",这种"调控作用"很好地解释了碳纳米管的生长速率、内部结构与成核后的双金属Mo-Fe催化剂粒子的关联性。

Chemical Vapor Deposition （CVD） is one of the most common methods for the preparation of vertical aligned carbon nanotubes （VA-CNTs）. As the catalyst particles are the templates for the growth of carbon nanotubes, adjusting the structure of the VA-CNTs by changing the structure of the catalyst particles is an important method for the synthesis of carbon nanotube arrays. Monometallic Fe is the most common catalyst for the growth of CNTs, while it＇s not easy to change its structure due to the single component. However, bimetallic catalysts have shown the potential advantages in the control synthesis of CNTs for the reasons that bimetallic catalysts have the advantages of adjustable components, simple process technology, easy amplification and so on. Here, we can control the size and diameter distribution of catalysts effectively through adding Mo into Fe and changing the ratio of Mo to Fe. Therefore, we can obtain the VA-CNTs with controllable density, orientation, wall number, quality and other structures. We speculate that the size and diameter distribution of Fe catalysts change due to the ＂adjust effect＂ of Mo catalysts, which provide a good expla- nation for the correlations between the growth rate and internal structure of CNTs and the bimetallic Mo-Fe catalyst.