Investigation On Preparation And Surface Chemical Modification Of Nano Onion-like Fullerenes

As an important member of fullerene family, nano onion-like fullerenes (NOLFs) have unique hollow cage and concentric shells structure, which endow nano onion-like fullerenes some special properties. Based on these properties, many potential applications, such as energy materials, high-performance and high temperature wear-resistance materials, superconductive materials and biomaterials, have been proposed. However, the development of their application in bio-medicine fields has been influenced because of their strong hydrophobicity. Now, the essential prerequisite to their performance and application are their synthesis at large scale and surface chemical modification.In this paper, radio frequency (RF) plasma and microwave (MW) plasma, which operates at low temperatures and low energy consumption, were used for synthesizing nano onion-like fullerenes from different coal and surface modifying by optimizing experimental parameters, which provides the basis for the study of NOLFs performance and application. Synthesis of NOLFs was also studied by DC arc-discharge in water, cyclohexane and polyethylene glycol solution. The morphologies and structures of the products were characterized by field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) techniques. The results revealed that NOLFs can be synthesized from Hongyuan coal and Huainan coal, but only the mixture of NOLFs and carbon nano tubes can be synthesized from Zibo coal; Fe nanoparticles encapsulating nano onion-like fullerenes (nano-Fe@NOLFs) can be synthesized from Hongyuan coal and ferrocene; The products deposited on Si substrate from Hongyuan coal and ferrocene are NOLFs, but the products collected from the reaction chamber walls are some metal nanoparticles and amorphous carbon instead of NOLFs.In the absence of ferrocene, NOLFs were synthesized from Hongyuan coal by MW plasma, but in the presence of ferrocene, a noval coal-based aligned carbon film was obtained. The DC arc-discharge in water, cyclohexane or polyethylene glycol solution resulted in the formation of NOLFs. The growth mechanisms of different methods were discussed briefly.In order to conduct chemical modification on NOLFs, oxygen was introduced into plasma atmosphere after Huainan coal and ferrocene were reacted in Ar plasmar for an hour. The morphologies and structures of the products were characterized by FESEM, HRTEM and FT-IR techniques. The results revealed that though the products were NOLFs, their surface were oxidized when the content of oxygen in atmosphere was increased to a threshold value. NOLFs(OH)_n and NOLFs(COOH)_n were formed when the content of oxygen was 3% or 4%, with more functional groups introduced at O₂ content of 4%. The formation mechanisms of the modified products were discussed.