Studies On Fullerenes Synthesis By Controllable High Temperature Pyrolysis With Graphite Furnace And Its Formation Mechanism

Carbon is one of the most well-known chemical elements in the world and it is also a very unusual element.Fullerenes are a class of hollow spherical molecules composed of carbon atoms.They are the existence form of the third carbon element discovered after graphite and diamond.In 1985,Sir Harold Walter Kroto,Robert F.Curl,Jr.,and Richard E.Smalley accidentally discovered fullerene(C60)in laser-evaporated graphite experiments.It has aroused widespread concern and research by scientists around the world.In consequence,three of them won the Nobel Prize in Chemistry in 1996.At present,the research of fullerenes has made great progress and development.There are more than a dozen methods for the synthesis of fullerenes.The most commonly used methods are graphite arc discharge method and flame combustion method.Although these two methods can prepare fullerenes in large quantities,there are still some problems,such as the trouble in controlling temperature in the arc discharge method,the bulky experimental devices,and the high cost.It is very necessary to find a fullerene synthesis method with more controllable parameters and more facilitation.In this thesis,we independently designed a graphite furnace by electric heating,based on which we investigate the fullerene synthesis conditions with the application of HPLC-MS,Raman spectroscopy,etc.The main research contents and achievements are as follows:1.We developed a novel fullerene synthesis device with graphite furnace electric heating system,in which heat is produced by large current on graphite and synthesis temperature is controllable and recordable.This synthesis device has many advantages such as simpler structure,easier operation and lower cost,providing a more convenient and reachable method in fullerene synthesis research.2.The developed graphite furnace electric heating synthesis device is used,and the synthesis conditions were also optimized in a series of conditional explorations.First,the effects of different gaseous reactants on the synthesis of fullerenes were investigated,including chloroform,carbon tetrachloride,dichloromethane,methyl chloride,methane,bromoform and dichloroethane.It was found that with graphite tube as reaction container,chloroform and dichloromethane were effective reactants capable of obtaining a fullerene product,and the amount provided in the reaction was directly related to the yield of fullerene.3.Also,solid carbon sources with various morphology were found important in the formation of fullerene.No C60 was observed when amorphous carbon was applied.Carbon resources with certain atomic arrangement,such as carbon nanotube,graphene,and diamond,were beneficial to produce C60.This provides a new understanding of the C60 formation mechanism.