【作者】 安玉良；

【导师】 邱介山；

【作者基本信息】 大连理工大学 ， 化学工艺， 2004， 博士

【摘要】 碳纳米材料具有独特的结构和众多奇异的物理化学性质,在诸多科学技术领域显示出巨大的潜在应用价值,近10年来逐渐成为国内外关注的一个研究热点。本论文以生物材料为基质制备碳纳米材料,并对其结构、性质及制备过程进行了较系统的研究,主要内容如下: 以一种具有空心结构的脱铁蛋白为纳米级限域性模板反应器合成碳包覆金属纳米材料,即:以脱铁蛋白(其空心结构由蛋白质肽链构成)作为合成碳包覆纳米材料的纳米级限域性模板反应器,首先采用化学组装技术方法将拟包覆金属的前驱体填充到蛋白质肽链构成的空腔内,然后在温和可控的条件下进行热处理,使蛋白质肽链热分解,其中生成的碳构成富勒烯类空心纳米壳体并将填充在蛋白质空心内部的金属材料包覆起来,得到碳包覆的金属纳米材料。考察了蛋白矿化反应参数对脱铁蛋白矿化组装结果的影响,并讨论了其矿化机理:分别采用真空炭化工艺、还原炭化工艺成功制备出粒度分布均匀的碳包覆锰、钴纳米材料;采用TEM和EDX等对产品结构和组成进行了表征分析,并初步讨论了碳包覆金属纳米材料的生长过程和机制。 以多糖(淀粉、纤维素)为基质通过控温还原炭化工艺成功制备出碳包覆金属纳米材料,综合采用TEM、HRTEM、SEM、EDX、XRD、Raman、IR光谱、UV-vis光谱等技术手段对产品的形态、结构、组成和性质进行了全面的分析研究。首先以淀粉为基质在氢气气氛下炭化制备出大量的碳包覆铁纳米材料,通过改变金属前驱体中金属氧化物的成分,成功制备出碳包覆FeCo复合金属纳米材料:以纤维素为基质采用还原炭化工艺亦成功地制备出碳包覆金属纳米材料:得到的碳包覆金属纳米颗粒呈准球形的核壳结构,粒度比较均一。这些结果表明,淀粉和纤维素是制备碳包覆纳米材料的理想碳前躯体。阐述了碳包覆金属纳米材料的形成机理;指出多糖基碳包覆纳米材料的形成过程包括炭化过程和催化石墨化过程两个阶段。此外,以淀粉为前躯体采用电弧法成功制备出形态规整的纳米碳球,其粒径分布均匀,石墨化程度高。 以铁蛋白为催化剂前躯体,采用化学气相沉积方法进行了碳纳米管的制备研究。以煤气为碳源气相生长出大量碳纳米管,对产品形态、结构进行表征分析,并对其生长的影响因素进行研究,优化了工艺参数;通过调节反应时间等参数成功制备出定向生长的碳纳米管阵列。实验进一步以含硫有机化合物(噻吩、二硫化碳)为碳源制备出Y形碳纳米管,结果表明硫是Y形碳纳米管生长的重要因素,并以此提出了Y形碳纳米管的生长机理:为进一步考察催化剂对碳纳米管生长的影响,以二茂铁为催化剂热解煤气制备出单壁碳纳米管,并对其形态、结构以及生长机理进行了研究。实验通过电化学测试分析考察了碳纳米管作为电极材料的可行性,发现碳纳米管作为电容器的电极材料具有良好的电化学性能和较高的稳定性。更多还原

【Abstract】 Carbon nanomaterials are currently the focus of research around the world because of their unique microstructures and extraordinary properties as well as great potential in many fields of science and technology. In this thesis the possibility for preparing carbon nanomaterials based on natural biomaterials has been explored, and the morphology, structure and properties of the obtained carbon nanomaterials are systematically studied, on the basis of which the growth mechanism of carbon nanometerials are addressed.A novel approach for preparing carbon encapsulated nanomaterials with apoferritin as the starting nano-sized reactor has been developed, in which apoferritin molecules, a kind of biomaterial with hollow cages, is used to trap the precursors of metals to be encapsulated. The results show that the nano-sized metal particles can be effectively encapsulated inside the carbon shells resulting from the pyrolysis decomposition of protein molecules under mild and controllable conditions. Carbon encapsulated Mn and Co nanomaterials are prepared by carbonization under vacuum conditions or in flowing hydrogen, respectively. The mechanisms of mineralization and carbonization are discussed in terms of the structure and properties of protein.A practical and efficient route is developed for the first time for making carbon encapsulated metal nanomaterials with amylase (starch and cellulose) as the starting material. It has been found that Fe particles can be effectively encapsulated inside carbon shells by carbonizing mixtures of starch and iron oxide in flowing hydrogen. Following the above route, carbon encapsulated bimetallic particles are also synthesized successfully. The preparation of carbon encapsulated nanomaterials with cellulose as the starting material is also successful, which is attributed to the similarity in composition and structure of starch and cellulose. The results demonstrate that both starch and cellulose are one of the ideal carbon precursors for preparing carbon encapsulated nanomaterials. The products are characterized using a number of techniques including TEM, HRTEM, SEM, EDX, XRD, Raman, IR and UV-vis. It has been found that carbon encapsulated nanomaterials have an ideal core-shell structure with a narrow size distribution. In addition, preliminary results show that carbon nanoballs with a narrow size distribution can also be made from starch via arc discharge method. The mechanism involved in the growth process of carbon encapsulated nanomaterials is also addressed, in which it is believed that two steps, i.e. the thermolysis of precursor and the catalytic graphitization of carbonized materials, are involved.The possibility of making carbon nanotubes (CNTs) from different carbon-containing sources via chemical vapor deposition method is also explored, in which biomaterials ororganic substance are used as catalysts. With ferritin as catalyst, CNTs are prepared for the first time from coal gas, which leads one to believe that ferritin is an ideal catalyst precursor for controlling growth of carbon nanotubes and coal gas is one ideal carbon source for CNTs. Under the optimized conditions, it is also possible to prepare aligned CNTs. With organic sulfur compound as carbon source, Y-junction CNTs are obtained, of which the growth mechanism is briefly discussed. The results show that sulfur may play a key role for the growth of junctions. Furthermore, single walled CNTs are synthesized from coal gas when ferrocene is used as catalyst, indicating that catalyst has an important effect on morphologies and structures of CNTs. In addition, the potential of CNTs in the field of electrochemistry is explored, of which the preliminary results lead one to believe that CNTs is an ideal electrode materials for superocapacitors.更多还原