【作者】 沈博；

【导师】 张以河；

【作者基本信息】 中国地质大学（北京） ， 岩石矿物材料学， 2014， 博士

【摘要】 天然鳞片石墨是一种储量丰富的矿物材料，通过加工使其纳米化可以带来独特理化性能。石墨烯是一种新型纳米碳材料，可以从天然鳞片上剥离得到，具有奇特的电学、光学、力学和热学性质，有望应用于晶体管、纳米器件以及高性能电池等方面。本论文以石墨烯的制备及复合应用为主线，研究了石墨烯的制备、复合及其复合材料的介电、光催化性能。本文首先研究了石墨烯的探索制备。分别采用直接氧化法和预氧化法制备得到氧化石墨，而后采用不同的还原剂还原得到石墨烯，通过SEM、TEM和AFM分析了石墨烯的形貌特征，进行了FTIR、XRD表征。结果表明，预氧化法制备的氧化石墨氧化程度更高，水合肼做还原剂能更好的将氧化石墨还原，所得石墨烯的导电率达到1.11×103s/cm，为下一步复合材料的制备提供了保证。其次，制备了有银粒子负载的载银石墨烯材料，并以此为填料，聚酰亚胺为基体，采用原位聚合的方法制备了载银石墨烯/聚酰亚胺复合薄膜；作为对照制备了石墨烯/PI复合薄膜。重点研究了填料含量及分散状态对纳米复合材料介电性能的影响。研究表明,石墨烯和载银石墨烯在PI中呈一定的取向，载银石墨烯比石墨烯更易分散，两种复合薄膜的介电规律都符合渗流理论。石墨烯/聚酰亚胺复合薄膜和载银石墨烯/PI复合薄膜的的渗流阈值分别仅为0.9vol%和1.07vol%，而介电常数最高可达到13.87(100Hz)和8.91(100Hz)，具有较低的频率依赖性，并且介电损耗较小，为10-2数量级。最后，以氧化石墨烯为载体，在其上负载半导体材料，制备得到纳米氧化亚铜/还原石墨烯(Cu2O/rG)复合材料和磷酸铋/还原石墨烯(BiPO4/rG)复合材料，并研究了两者的光催化性能。研究表明石墨烯的加入对Cu2O的微观形貌以及BiPO4的晶型产生极大影响，同时导致Cu2O和BiPO4的禁带宽度变大，石墨烯良好的导电性可以使光生电子迅速转移，从而降低光生电子空穴复合率，使得复合材料的光催化性能提高。Cu2O/rG复合材料对TNT红水具有一定的光催化效果，对TNT红水的降解率最高可达42.6%；BiPO4/rG复合材料对亚甲基蓝溶液具有很好的光催化效果，其光催化反应符合一阶动力学，降解动力学常数k值最高可达k=0.064min-1。更多还原

【Abstract】 Natural flake graphite has been widely used in different fields and its derivativeshave excellent performances. Graphene, which can be exfoliated from graphite，is anew carbon nanomaterial and is of great interest owing to its unique electronic, optical,mechanical, and thermal properties. The discovery of graphene is opening up a newresearch area for condensed-matter physics, materials science, and benefitinghigh-dielectric-constant materials. This paper focused on the graphene composites andtheir properties. Emphasis was placed on preparation, modification of graphene andthe dielectric and photocatalysis properties of its composites.First, the preparation process of graphene is studied and optimized. Grapheneoxide (GO) prepared with direct oxidation and pre-oxidationsuper respectively, isreduced by different reductants. The reduced products are characterized by scanningelectron microscopy, transmission electron microscopy, infrared spectroscopy, atomicforce microscope and X-ray diffraction. Results indicated that the GO prepared withpre-oxidationsuper presented larger oxidation degree, and the graphene which wasreduced by hydrazine hydrate showed highest conductivity (1.11×103s/cm).Secondly, sliver-loaded graphene composite where graphene was modified by Agnanoparticles was prepared, and then the sliver-loaded graphene/PI composites werefabricated by in-situ polymerization. As a contrast, graphene/PI composites, withgraphene as the filler and PI as the matrix, were fabricated by in-situ polymerization.The relationships between effects of sliver-loaded graphene or graphene volume anddispersion on dielectric properties of composites were discussed. Results indicatedthat graphene and sliver-loaded graphene were oriented to a certain extent in PI. Ahigh dielectric constant of13.87(100Hz) was obtained when the concentration ofgraphene was0.9vol%. The percolation threshold of sliver-loaded graphene/PInanocomposites was fc=1.07vol%, and when volume fraction of grapheme reachedthe percolation threshold, dielectric constant of sliver-loaded graphene/PI compositewas8.91(100Hz).Finally, cuprous oxide and bismuth phosphate loaded on reduced grapheme oxidewere prepared respectively by the method of sedimentation-reduction andhydrothermal synthesysis. The microstructure and properties of both composites werestudied. The addition of reduced graphene oxide changed the microstructure ofcuprous oxide, and the form of bismuth phosphate crystal was also affected. The photocatalytic research results of composites showed that the photocatalyticdegradation of red water could reach42.6%by Cu2O/rG composite, and the dye MBcould be effectively photocatalytically degraded by BiPO4/rG composite.更多还原