【作者】 张帆；

【导师】 崔屾；

【作者基本信息】 天津大学 ， 物理化学， 2013， 博士

【摘要】 本文采用直流电弧放电法，分别制备了碳-铁纳米复合材料以及碳-氮纳米材料，其中碳-铁纳米复合材料包括碳包覆铁纳米颗粒（CEINPs）和铁纳米颗粒/石墨烯纳米复合材料（Fe/GNCs）。使用TEM、HRTEM、SEM、EDX、XRD、Raman光谱、XPS和TG-DSC等对电弧放电产物进行表征，考察了原料配比和阳极棒制备方法对制备CEINPs和Fe/GNCs的影响；还考察了原料配比、放电室抽洗、过渡金属催化剂使用、不锈钢片熔化和阳极棒制备方法对碳-氮纳米材料形貌和N含量的影响；初步探讨了CEINPs和Fe/GNCs的生成机理。以质量比为9:1的Fe2O3与石墨的混合物为原料，分别采用填充与压制法制备阳极棒。使用模具Ⅰ压制的阳极棒进行电弧放电，成功地制备了具有高铁含量（82.6%）的、近似球形的、且具有典型的核-壳结构的CEINPs，收率达到了约22.3wt.%；内核主要由含量相近的-Fe和Fe3C组成；内核的粒径分布在3-37nm，平均粒径约为20.6nm；外壳则由3-7层石墨层结构组成，层间距约为0.348nm；主要由CEINPs组成的产物具有铁磁性行为。同次实验得到的C内芯中以层间夹杂高铁含量球形颗粒的多层石墨烯为主。使用模具Ⅱ压制的阳极棒进行电弧放电，得到的C内芯中以Fe/GNCs为主，即在石墨烯片中分布着粒径约为3-6nm的铁纳米颗粒；但是在石墨烯片之间分布着粒径为0.1-2.2m的高铁含量的球形颗粒；该C内芯产物在室温条件下具有超顺磁性。使用填充阳极棒进行电弧放电，产物B主要是分布在碳材料上的铁物种颗粒，碳材料具有不完整、无序的层状结构；产物C内芯中也是以多层石墨烯为主。分别以6组不同的实验条件制备碳-氮纳米材料，重点考察了产物B和C内芯。前者均以颗粒和片状物为主，后者均以片状物为主。两者均以碳物种为主，N含量很低，尤其是后者。N含量随着颗粒直径的增加而增加（在一定尺寸范围内）；原料中高氮化合物含量的提高以及不锈钢片熔化均有利于提高产物中的N含量；使用过渡金属催化剂对产物中的N含量无明显影响。阳极棒各组分分布的均匀性、铁含量、铁元素的微电场和微磁场作用、N2进气温度、电弧放电区域与冷却铜管内壁之间的温度和浓度梯度等因素均可能对CEINPs和Fe/GNCs的生成起着重要作用。更多还原

【Abstract】 In this thesis, carbon-iron nanocomposites, including carbon-encapsulated ironnanoparticles (CEINPs) and iron/graphene nanocomposites (Fe/GNCs), andcarbon-nitrogen nanomaterials were prepared by DC arc discharge method,respectively. The products were characterized by TEM, HRTEM, SEM, EDX, XRD,Raman spectroscope, XPS, and TG-DSC. The effects of the ratios of raw materialsand methods of preparing anode on the preparations of CEINPs and Fe/GNCs wereinvestigated. The effects of the ratios of raw materials, pumping the arc dischargechamber, utilization of transition metal catalyst, melt down of stainless steel sheets,and methods of preparing anode on the morphology and the content of nitrogen ofcarbon-nitrogen nanomaterials were also investigated. The possible processes offormation of CEINPs and Fe/GNCs were discussed briefly.The anodes were prepared by the filling and compacting method respectively witha mixture of90wt.%iron(III) oxide and10wt.%graphite powders as raw material.The CEINPs with high iron content (82.6wt.%), quasi-spherical, and goodcore-shell structure can be successfully prepared in high yield (22.3wt.%) by DCarc discharge, using the anode prepared by the compacting method with the mold I.The cores of CEINPs mainly consist of-iron and iron carbide with similar contents;the diameters of the cores are in the range of3-37nm and their average diameter isabout20.6nm; the shells consist of about3-7graphitic layers and the interlayerspacing is about0.348nm; the product, mainly composed of CEINPs, shows typicalferromagnetic behavior. And the product CIC, prepared in this experiment, mainlyconsists of multi-layer graphene, and some quasi-spherical particles with high ironcontent are distributed among the graphene nanosheets.The product CIC, which mainly consists of Fe/GNCs, is prepared by DC arcdischarge, using the anode prepared by the compacting method with the mold II. TheFe/GNCs are the iron nanoparticles with diameters of3-6nm inside graphene, butsome quasi-spherical particles with diameters of0.1-2.2m and high iron contentare distributed among the graphene nanosheets. The product CICshows thesuperparamagnetic behavior at room temperature.When the anode prepared by the filling method was used, many iron species nanoparticles in the product B are enwrapped in the carbon material; the carbonmaterial shows imperfect and disordered layer structure. And the product CICmainlyalso consists of multi-layer graphene.The carbon-nitrogen nanomaterials were prepared under six groups of differentexperimental conditions, respectively. The products B and CICare investigatedmainly. The former mainly consists of the particles and flakes, and the latter mainlyconsists of the flakes. The carbon contents in them are very high, but the nitrogencontents are very low, especially in the latter. The nitrogen contents of the particlesin the products B increase with the increase of the particle sizes (within certainrange); both the increase of the amount of high nitrogen compound in raw materialand the melt down of stainless steel sheets are beneficial to improve the nitrogencontents in the products; the utilization of transition metal catalyst has no obviouseffect on the nitrogen contents in the products.The uniformity of compositions of anode, the content of iron, the microelectricfield and micromagnetic field of iron element, the inlet temperature of nitrogen, andgradients of temperature and concentration between the region of arc discharge andthe inner wall of cooling copper tube may play an important role in the formation ofCEINPs and Fe/GNCs.更多还原