【作者】 卓其奇；

【导师】 孙旭辉；

【作者基本信息】 苏州大学 ， 材料学， 2013， 博士

【摘要】 石墨烯独特的电子结构使其具有优异的性质，如高的电子迁移率、大的比表面积、良好的透光性、高的杨氏模量和优异的热学性质。自从用机械剥离法从石墨中分离出石墨烯以来，很多方法被应用于合成石墨烯，例如化学气相沉积法、化学氧化还原法、有机合成法等。目前，如何可控合成高质量、大规模、低成本石墨烯依旧是限制石墨烯应用的重要因素。本论文进一步发展了化学氧化还原和化学气相沉积两种方法来合成石墨烯。首先，我们研究了Hummer法合成出的氧化石墨烯的氧化量，发现通过控制氧化剂的加入量，可以得到不同氧含量的氧化石墨烯。FTIR和Raman研究表明，含氧量的增加会使氧化石墨烯中sp3碳的杂化比例增大。通过测量不同含氧量氧化石墨烯的电势发现，氧化石墨烯的含氧量越高则电势越低。另外，氧化石墨烯之间的静电斥力也是影响氧化石墨烯在水溶液中分散的重要影响因素。目前，很多还原剂被应用于还原氧化石墨烯，例如水合肼及其衍生物。但是，这些还原剂毒性极大且容易挥发，限制了它们的使用。第三章介绍了一种在室温下用金属纳米颗粒来催化硼氢化钠水解从而来还原氧化石墨烯的简便方法。分别用原子力显微镜和透射电镜研究了石墨烯的形貌和结构。通过紫外-吸收光谱、X射线光电子能谱、拉曼光谱和X射线衍射研究了氧化石墨烯的还原过程。该方法避免使用水合肼及其衍生物作为还原剂，具有环保安全的优点。同时该方法在温和的条件（室温）下进行，得到的石墨烯缺陷较少，并且该方法可以放大使用，作为催化剂的金属盐可以被重复利用。石墨烯@金属纳米颗粒复合物具有特殊的结构和优异的性质，可以应用到催化、电极、传感器等领域中。金属纳米颗粒的尺寸和形貌会直接影响到石墨烯@金属纳米颗粒复合物在实际应用中的使用。第四章介绍了一种通过自催化在室温下合成石墨烯@金属纳米颗粒复合物的简便方法。首先，将需求尺寸和形貌的金属纳米颗粒负载到氧化石墨烯上，然后通过金属纳米颗粒作为催化剂来加速硼氢化钠水解去还原氧化石墨烯，通过得到石墨烯@金属纳米颗粒复合物。相比已有的方法，该方法避免使用水合肼及其衍生物等剧毒还原剂，环保安全，且该方法可以在室温下和不同酸碱度下高效进行。同时该方法可以用来大规模的合成石墨烯@金属纳米颗粒及石墨烯@金属氧化物纳米颗粒复合物，从而满足其实际应用。例如，石墨烯@Au纳米颗粒复合物在催化和太阳能电池方面展现出良好的应用。在绝缘体上生长出高质量、大面积石墨烯是微电子行业的迫切需求，第五章中介绍了一种利用多环芳烃(例如ADN、HAT-CN和NPB)或氧化石墨烯作为碳源，金属Cu作为催化剂无需转移直接将石墨烯生长到绝缘材料上的新方法。分别探讨了碳源、生长温度、H2含量及催化剂和碳源厚度对生长石墨烯的影响。目前的研究结果表明，HAT-CN可以在相对较低的温度下生长出石墨烯。用5nm的碳源可以生长出单层的石墨烯，随着碳源厚度的增加，石墨烯的质量下降。同时，该方法可以用来合成合成氮掺杂和不同图案的石墨烯。更多还原

【Abstract】 Graphene has attracted enormous attention due to its unique structure andextraordinary properties, such as high carrier mobility, high surface area, good opticaltransparency, high Young’s modulus and excellent thermal conductivity. Sincesuccessful isolation of graphene by the mechanical exfoliation of graphite, manymethods have been developed to synthesize graphene, including chemical vapordeposition (CVD), chemical reduction graphene oxides, organic synthesis from micromolecule, etc. To date, however, rational synthesis of graphene with high quality andlarge quantity at low cost is still a key issue in the pratical applications of graphene. Inthis thesis, the endeavor has been mainly focused on the development of two syntheticstrategies of graphene, chemical redox method and CVD approach.We have firstly studied the oxidation level of the graphene oxide in the modifiedHummer method. The amount of oxygenated functional groups in the GO can be variedby changing the amount of oxidant. FTIR and Raman results show the sp3C domainsincrease with the increase in oxidation level. The oxygenated functional groups in GOsignificantly alter the potential of GO; the higher oxidation level of GO, the lowerpotential. In addition, electrostatic repulsion between the GO nanosheets is an importantfactor on the GO dispersibility in aqueous solution.So far, a number of chemical reductants have been developed to chemicalreduction of GO. For example, hydrazine or its derivatives as strong reducing agentwere used for the reduction of GO. However, these reductants are highly toxic andexplosive, which limited their usage. In third chapter, a simple chemical approach hasbeen developed for the synthesis of graphene through a mild reduction of grapheneoxide (GO) using metal nanoparticles as a catalyst for the hydrolysis reaction of NaBH4at room temperature. The morphology and structure of the graphene were characterizedwith atomic force microscopy and transmission electron microscopy. The reductionprocess and quality of graphene were followed and examined by UV-Vis absorption spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and X-raydiffraction. By this method, graphene can be prepared in large quantity without usingtoxic reducing agents such as hydrazine or its derivatives, making it environmentallybenign. The reaction is conducted under mild conditions (room temperature), resultingin the formation of fewer defects. The method can be easily scaled up and the metalcatalyst can be recycled.Graphene@metal nanoparticles (NPs) composites have attracted great interests invarious applications such as catalyst, electrode, sensor, etc. due to their uniquestructures and extraordinary properties. A facile synthesis of graphene/metal-NPscomposite with good control of size and morphology of metal NPs is critical to thepractical applications. A simple method to synthesize graphene/metal-NPs undercontrollable manner via a self-catalysis reduction at room temperature has beendeveloped in fourth chaprter. At first, metal NPs with desirable size and morphologywere decorated on GO, and then used the metal NPs as catalyst to accelerate thehydrolysis reaction of NaBH4to reduce the graphene oxide. Compared to the existingmethods, the method reported here features the several advantages whichgraphene/metal are prepared without using toxic and explosive reductant such ashydrazine or its derivatives, making it environmentally benign and the reaction can beprocessed at room temperature with high efficiency and in a large range of pH value.The approach has been demonstrated to successfully synthesize graphene compositewith various metal NPs at large quantity, which opens up a novel and simple way toprepare large-scale graphene/metal or graphene/metal oxide composite under a mildcondition for the practical applications. For example, graphene/AuNPs compositesynthesized by the method shows excellent performance in the catalysis and solar cellapplications.Direct formation of high-quality and wafer scale graphene on dielectric substrate isemergent for electronic application of graphene. In fivth chapter, we report atransfer-free method to directly synthesize graphene on dielectric substrate usingpolycyclic aromatic hydrocarbons (PAHs)(e.g. ADN, HAT-CN, NPB) or GO as thesolid carbon source and Cu layer as the catalyst covering on the solid carbon source.The effects of different carbon source, growth temperature, H2content, thickness ofcatalyst and carbon source, have been investigated. According to the results, HAT-CNcan be used to synthesize graphene at relatively low temperature. The monolayer graphene has been obtained with5nm carbon source. With increase the thickness ofcarbon source, the quality of graphene will decrease. By this method, N-doping andpatented growth of graphene can be easily achieved.更多还原