Preparation Of N-doped Carbon Nanomaterials By DC Arc Discharge

In this thesis, the padding and compacting methods were used to prepare anodesrespectively and N-doped carbon nanomaterials were prepared by DC arc dischargemethod. The products were characterized by using scanning electron microscope(SEM), field emission high resolution transmission electron microscope (HRTEM),energy dispersive X-ray (EDX) spectrometer, electron energy loss spectroscopy(EELS), and transmission electron microscope (TEM). The effects of the substratepositions relatived to the arc discharge zone, the kinds of substrate, the ratios ofpadding materials, the discharge chamber pumping, usage of transition metal catalystand the methods of preparing anode on the morphology of the products wereinvestigated. The possible processes of formation of N-doped long bamboo-likecarbon nanotubes were discussed briefly.The results of SEM characterization indicate that for the substrates which wereput above, below and at the side of arc discharge zone, the kinds of substrate havesignificant impact on the morphology of the products deposited on the substrates, butthere is no obvious regularity; the putting positions of the substrates relatived to thearc discharge zone have obvious impact on the morphology of deposits, the ratios ofpadding materials and the discharge chamber pumping also have certain influence onthe morphology of deposits, the usage of transition metal catalyst has significantimpact on the morphology of the products.The results of TEM characterization reveal that the ratios of padding materials,the discharge chamber pumping, usage of transition metal catalyst and the methods ofpreparing anode have certain effect on the morphology of the products deposited onthe inner surface of stainless steel circle placed around arc-discharge zone.The results of TEM, HRTEM and EELS characterization show that N-dopedlong bamboo-like carbon nanotubes were formed on the inner surface of stainlesssteel circle placed around arc-discharge zone, when the discharge chamber waspumped, the transition metal catalyst was used and the stainless steel sheets weremelted. The length of the bamboo-like carbon nanotubes were between640-840nm,the inner diameters were between23-35nm and the outer diameters were between 28-47nm. In each of the inner cavities formed at the "bamboo joints" there is a blacknanoparticle. All kinds of carbon and nitrogen reactive species which were generatedby arc discharge rapidly self-assembled to generate N-doped bamboo-like carbonnanotubes, under the functions of the iron, cobalt, nickel and their metal alloy crystalnucleus formed due to condensation and their micro electric field and micro magneticfield and the gradients of temperature and concentration.The results of this thesis have important practical significance and certaintheoretical significance for using DC arc discharge to perpetrate special morphologyof nitrogen doped carbon nanomaterials on different substrates. The results of thisthesis have provided important experimental basis and also have certain theoreticalsignificance for the development of arc discharge chemistry.