电弧放电中纳米洋葱状富勒烯生成机理的研究

Studies on the Growth Mechanism of Nano-onion-like Fullerenes in Arc Discharge

探索了用传统的电弧放电法、在现有的电弧放电装置中 ,通过改进放电工艺、添加催化剂制备纳米洋葱状富勒烯 (NanoOnion likeFullerenesNOLFs)的过程和工艺。用高分辨透射电镜 (HighResolutionTransmissionElectronMicroscopeHRTEM)对生成的NOLFs进行了形貌、结构的观察与表征。分析结果表明NOLFs晶化程度很高 ,直径均匀 (2 0～ 5 0nm)。生成的NOLFs可分为两大类 :(1)内包金属纳米微粒的NOLFs;(2 )单体NOLFs。对NOLFs的生成机理及催化剂对其直径、收率的影响进行了讨论。据此建立的汽 -液 -固 (Vapor Liquid Solid :VLS)生长模型可以解释实验中出现的一些现象。研究表明生成NOLFs的数量、直径分别与催化剂的活性及其尺寸有关。

The synthesis of onion like fullerenes was investigated by traditional DC arc discharge method, using nano sized catalysts in a modified arc discharge apparatus. A high resolution transmission electron microscope (HRTEM) was used to characterize the morphologies and microstructures of the product. HRTEM observations indicated that the typical nano onion like fullerenes are highly crystallized, with uniform external diameter of about 20～50nm.Two kinds of nano onion like fullerenes were observed: 1) Nano onion like fullerenes encapsulating catalyst nanoparticles; 2) Individual onion like fullerenes. The growth mechanism of nano onion like fullerenes and the effect of catalyst particle on product diameter and yield were discussed. The VLS growth model was used to explain some experimental phenomena. Results showed that the diameter and yield of nano onion like fullerenes are affected by catalyst activity and particle size.