氧化石墨烯的制备及结构控制

发布时间：2018-03-03 02:17

本文选题：氧化石墨烯　切入点：环境友好制备　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：氧化石墨烯(GO)是化学转化石墨烯的前驱体,也是被研究最多的石墨烯衍生物。本论文系统研究了GO的制备以及结构控制新技术,揭示了其原理。主要内容如下:开发了不加硝酸钠改进的Hummers方法制备GO。去除硝酸钠之后对GO的收率,片层尺寸和官能化程度几乎没有影响,但带来如下优点:(1)避免了有毒气体氮氧化物的排放;(2)简化了废液后处理,实现整个反应的环境友好化,降低了环境负担;(3)制备得到的GO及其还原氧化石墨烯(rGO)的结构完整性更好。通过将原料325目石墨片改为尺寸更小且更均匀的1200目石墨片,在不改变反应条件的前提下实现了GO的高产率制备。制备得到的GO1200和GO325的结构完整性相似,但前者的产率(171±4%)远高于后者(110±3%)。1200目石墨片可以被完全氧化,产物无需离心提纯;因此,降低了生产成本,简化了操作步骤,更适合工业化规模生产。通过在反应体系中添加适量水改进的Hummers方法实现了组成和结构可调GO的可控制备。在40°C反应过程中加入一定量的水可以在保持GO结构完整性的前提下选择性地调控GO环氧和羟基官能团的含量;在40°C反应结束后继续进行95°C氧化反应可以选择性地生成更多羧基,但GO的结构完整性较差。加水改进的Hummers方法还可以大幅度提升低温(0°C)制备的低结构缺陷GO的产率。通过实验对加入水带来的一系列变化进行了机理解释。该加水改进的方法适用于大规模制备结构完整性、官能团可控的GO。通过径迹刻蚀膜过滤对GO进行了有效尺寸分级。此方法可以将大小不同的GO片层分级成为多个尺寸分布窄的部分,而且简单、经济、能耗低、环境友好,并可与GO的制备集成自动化。GO尺寸能够影响石墨烯材料的结构与性能。大尺寸的GO的官能团相对更少,其制成的膜堆叠更紧密而有序,相应的力学性能更优。大尺寸的GO还原后制成的rGO膜具有更高的导电率。本方法还可应用于其他微米级的物质的尺寸分级。
[Abstract]:Graphene oxide (GOO) is the precursor of chemically transformed graphene and the most studied graphene derivative. In this paper, the preparation of go and the new technology of structure control were systematically studied. The main contents are as follows: a new Hummers method without sodium nitrate has been developed to prepare go. The removal of sodium nitrate has little effect on the yield, lamellar size and functionalization of go. But with the following advantages: 1) avoiding the emission of noxious nitrogen oxides 2) simplifies the reprocessing of the waste liquid and makes the whole reaction environmentally friendly. The structural integrity of go and its reductive graphene oxide (rGO3) was better by changing 325 mesh graphite sheet into a smaller and more uniform 1200 mesh graphite sheet. The high yield of go was prepared without changing the reaction conditions. The structural integrity of the prepared GO1200 and GO325 were similar, but the yield of the former was much higher than that of the latter. It reduces the production cost and simplifies the operation steps. It is more suitable for industrial scale production. The controllable preparation of go with adjustable composition and structure can be realized by adding proper amount of water to the reaction system, and a certain amount of water can be added to the reaction system to maintain go structure. On the premise of integrality, the content of go epoxy and hydroxyl functional groups was controlled selectively. Further 95 掳C oxidation after the 40 掳C reaction can selectively produce more carboxyl groups, However, the structural integrity of go is poor. The improved Hummers method with water addition can also greatly increase the yield of low structure defect go prepared at low temperature (0 掳C). The mechanism of a series of changes caused by adding water is explained by experiments. The improved method is suitable for large-scale preparation of structural integrity. The functional group controllable go. Through track etching membrane filtration, go can be classified into several parts with narrow size distribution. This method is simple, economical, low energy consumption and environment-friendly. The structure and properties of graphene materials can be affected by the automatic. Go size can be integrated with go preparation. The functional groups of large go materials are relatively less, and the stacking of the films made by go is more compact and orderly. The corresponding mechanical properties are better. The large size go reduced rGO films have higher conductivity. This method can also be applied to the size classification of other micron materials.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.11

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