化学修饰石墨烯膜的可控制备与应用

发布时间：2018-03-01 20:45

本文关键词： 化学修饰石墨烯膜复合材料柔性超级电容器膜分离　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：石墨烯是由碳原子组成的具有单原子厚度的二维晶体材料。结构完整的石墨烯具有优异的力学、电学、光学和热学性质,但是溶解性差,很难进行溶液加工。化学修饰石墨烯,包括氧化石墨烯(GO)和还原氧化石墨烯(r GO),不仅具有可加工性,而且保留了部分石墨烯的优异性质。因而在复合材料、能量存储、催化和传感等领域具有广阔的应用前景。具有二维片状结构的化学修饰石墨烯是独特的构筑基元,可组装成各种功能性薄膜。本论文系统研究了化学修饰石墨烯膜的制备,结构控制,以及在高强度结构材料、柔性超级电容器和膜分离方面的应用。主要研究内容和结果如下:将蚕丝蛋白(SF)均匀嵌入GO片层之间制得了SF/GO复合膜。SF和GO之间的静电和氢键相互作用可以增加GO片层间的粘合力,从而提高了复合膜的力学性能。加入15 wt%的SF后,SF/GO复合膜的强度达到了221.3±16.4 MPa,是纯GO膜(114.1±24.1 MPa)的近两倍。将聚乙烯吡咯烷酮(PVP)嵌入r GO片层之间,制备了具有高强度和高导电性的PVP/r GO复合膜,克服了r GO片层不可逆堆叠的问题。当PVP质量分数为45%时,PVP/r GO复合膜具有致密的结构和很好的柔韧性,强度达到了121.5±10.8 MPa,电导率为247.9 S/m。基于该复合膜的全固态超级电容器不仅具有很好的柔性,而且体积比电容高达67.4 F/cm3(电流密度1A/g)。在100 A/g的超高电流密度下,其体积比电容仍高达51.2 F/cm3。研究了GO膜在有机溶剂中半透性产生的机理及半透性调控方法。GO膜在不同有机溶剂中的溶胀程度不同,因而具有不同的层间距。因此,可以通过选择不同的溶剂或溶剂组合来调节GO膜的半透性。例如,当用乙醇作溶剂时芘分子可以通过GO膜,但是当用正己烷或甲苯作溶剂时,芘分子则不能透过GO膜。另外,热处理也能调节GO膜在有机溶剂中的溶胀程度,从而调节其半透性。随着热处理温度的升高,溶于乙醇中的各种分子透过GO膜的速度均会降低。通过真空抽滤法在尼龙微滤膜表面沉积了一层超薄的溶剂化r GO(S-r GO),制得了S-r GO复合纳滤膜。在甲醇溶剂中,该复合膜可以截留带负电的小尺寸溶质分子和尺寸大于3.4 nm的中性分子,溶剂通量高达~75L/m2·h·bar。该复合膜能耐受强酸、强碱和强氧化性等苛刻的化学环境。
[Abstract]:Graphene is a two-dimensional crystal material composed of carbon atoms with the thickness of a single atom. Graphene with intact structure has excellent mechanical, electrical, optical and thermal properties, but its solubility is poor and it is difficult to process in solution. Including graphene oxide (GOO) and reduced graphene oxide (GOG), not only have processability, but also retain some of the excellent properties of graphene. The chemically modified graphene with two-dimensional flake structure is a unique architectural unit and can be assembled into various functional films. In this paper, the preparation of chemically modified graphene films has been systematically studied. Structural control, as well as structural materials in high strength, Applications of flexible supercapacitors and membrane separation. The main research contents and results are as follows: the electrostatic and hydrogen bond interactions between SF/GO composite membrane. SF and go can be increased by embedding silk protein into go layer. The adhesion between go layers, The strength of SF- / go composite membrane was 221.3 卤16.4 MPa after adding 15 wt% SF, which was nearly twice as high as that of pure go membrane (114.1 卤24.1 MPa). PVPs were embedded between r go layers by polyvinylpyrrolidone (PVP). High strength and high conductivity PVP/r go composite membranes were prepared, which overcome the irreversibly stacking problem of r go lamellae. When the mass fraction of PVP was 45, the PVP/r / r go composite membranes had dense structure and good flexibility. The strength is 121.5 卤10.8 MPa, the conductivity is 247.9 S / m. The all-solid-state supercapacitor based on this composite film is not only very flexible, but also has a volume ratio of 67.4 F / cm ~ 3 (current density 1 A / g 路g ~ (-1)). The specific capacitance of go membrane is still as high as 51.2 F / cm ~ (-3). The mechanism of semi-permeability of go membrane in organic solvent and its regulation method are studied. The swelling degree of go membrane in different organic solvent is different, so it has different layer spacing. The semi-permeability of go membranes can be adjusted by selecting different solvents or combinations of solvents. For example, when ethanol is used as solvent, pyrene molecules can pass through go membrane, but when n-hexane or toluene is used as solvent, pyrene molecules can not pass through go membrane. Heat treatment can also adjust the swelling degree of go film in organic solvent, thereby adjusting its semi-permeability. The velocity of various molecules dissolved in ethanol through go membrane will be decreased. A layer of ultra-thin solvated r GO(S-r goon was deposited on the surface of nylon microfiltration membrane by vacuum filtration method, and S-r go composite nanofiltration membrane was prepared. In methanol solvent, S-r go composite nanofiltration membrane was prepared. The composite membrane can intercept small size solute molecules with negative charge and neutral molecules larger than 3.4 nm, and the solvent flux is up to 75 L / m 2 路h 路h 路bar.The composite membrane can withstand harsh chemical environments such as strong acid, strong alkali and strong oxidation.
【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;TB383.2

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