活化稀土金属以宏量制备单壁碳纳米管

Activation of Rare Earth Metals for Bulk Growth of Single-Walled Carbon Nanotubes

过去的三十几年见证了制备单壁碳纳米管(SWNTs)的催化剂由传统金属到氧化物与碳化物的演变过程。由于传统催化剂所制备SWNTs的产量低且表征手段受限,因此难以建立催化剂组成与SWNTs手性分布之间的关系。基于此,利用稀土金属钕(Nd)作为催化剂,通过“碱性载体”策略,实现了SWNTs的宏量制备。SWNTs纯化后,通过多种电子显微技术以及光学表征手段对其进行了系统表征。700℃下,利用Nd催化剂实现了(6,5)型SWNTs的高选择性制备,与铁族金属催化剂所制备的SWNTs类似。基于Nd纳米粒子的低熔点特点,提出了Nd催化剂生长SWNTs的气-液-固成核机制,并利用生长动力学对SWNTs的手性分布进行了解释。

Significant catalyst evolution from conventional metals to oxides and carbides for the single-walled carbon nanotube(SWNTs)synthesis has been witnessed in the past 30 years.Link on catalyst composition and SWNT chirality distribution has rarely been established due to the insufficient characterizations on the products generally suffering low yield.Using a“basic support”strategy,a rare earth metal,namely neodymium(Nd),is activated for bulk synthesis of SWNTs.After the catalyst removal,the SWNTs were thoroughly characterized by various electron microscopy and optical spectroscopy techniques.At a reaction temperature of 700℃,highly selective synthesis of(6,5)species is achieved on the Nd catalysts,and is comparable to those grown from Fe-family metal catalysts.Taking account of the low melting point of Nd nanoparticles,the SWNT nucleation on Nd catalyst is proposed to follow a vapor-liquid-solid mechanism,where the growth kinetics mainly accounts for the obtained chirality distribution.