【作者】 张鑫；

【导师】 袁才登；

【作者基本信息】 天津大学 ， 化学工程， 2020， 硕士

【摘要】 石墨烯气凝胶(graphene aerogels,GA)作为二维石墨烯的三维组装体,其高比表面积、高孔隙率和高导电性的特点吸引了众多研究者的目光,以GA为基体的吸附剂、光催化剂、传感器、电极材料等在多个领域研究进展迅速。然而传统方法制备的GA内部多孔结构是随机排列的,孔径、孔型的随机性无法满足很多应用的要求,因此如何以简单的工艺实现GA的可控组装是目前研究的重点。本文主要研究了模板法石墨烯气凝胶的制备及其在吸附和锂硫电池电极领域的应用。调配了一种GO/环己烷/正丁醇乳液作为石墨烯气凝胶的模板,在乳化剂的帮助下体系能够在2h内保持稳定。乳液内部GO悬浮液作为连续相,有机油滴作为分散相,有机油滴在水热反应过程中作为物理阻隔形成石墨烯水凝胶(GAH)内部的空腔。同时研究了石墨烯水凝胶制备的工艺参数,实验结果表明:当10g乳液辅助还原剂用量为50 μl、水热温度为150℃、水热时间为6 h时制备的GAH效果最佳。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱、X射线光电子能谱(XPS)、全自动比表面积及孔隙分析仪(BET)等方法对比了传统水热法制备的气凝胶(GA)和软模板法制备的气凝胶(GA-T)在外观、内部结构、内部组成和常见气凝胶物理参数方面的异同点。在对污染物吸附研究中,GA-T和其进一步煅烧得到的气凝胶(FGA)相比GA对正己烷和二甲苯的吸附量提升巨大,GA-T在海上溢油处理中表现出良好的应用前景。以FGA作为框架,升华硫作为主体制备了 FGA/S复合材料。将FGA/S作为锂硫电池正极材料,载硫量为60 wt%,组装成电池测试其电化学性能,发现锂硫电池在0.5C下的首圈比容量达到了 654 mAh g-1,相比GA/S正极,FGA/S正极电池在循环性能、库伦效率、倍率性能均有不同程度提升。通过循环伏安测试和阻抗测试可以看出,FGA的引入不仅提高了硫正极的电导率,而且提供了更多的反应位点和电子传输通道。更多还原

【Abstract】 Graphene aerogel(GA)is a three-dimensional assembly of two-dimensional graphene,which is attracted the attention of many researchers,due to its high specific surface area,high porosity and high electrical conductivity.GA-based materials developed rapidly in many fields,such as adsorbent,photocatalysts,sensors,electrode materials and so on.However,the internal porous structure of GA prepared by traditional methods is randomly arranged,and the applications was limited by the random pore size and pore type.Therefore,how to realize the controlled assembly of GA with a simple process is the focus of current research.The main research content of this article is the preparation of template-based graphene aerogel and its application in the field of adsorption and lithium-sulfur battery electrodes,including the following three aspects:The GO/cyclohexane/n-butanol emulsion was prepared as a template for graphene aerogels,and the system was stable for 2 h with the help of emulsifiers.In the emulsion,GO acts as the continuous phase,and organic oil droplets act as the dispersed phase.The organic oil droplets act as a physical barrier during the hydrothermal reaction to form a cavity in the graphene hydrogel(GAH).At the same time,the process parameters of graphene hydrogel preparation were dicussed.The experimental results show that the best GAH was obtained at the emulsion dosage of 10 g,the reducing agent dosage of 50 ul,hydrothermal temperature of 150℃ within 6 h.Scanning electron microscopy(SEM),X-ray diffraction(XRD),Raman spectroscopy,X-ray photoelectron spectroscopy(XPS),fully automatic specific surface area and pore analyzer(BET)were used to compare the similarities and differences in appearance,internal structure,internal composition and common aerogel physical parameters between the aerogel prepared by traditional hydro thermal method(GA)and the aerogel prepared by the soft template method(GA-T).In the study of pollutant adsorption,GA-T and its further calcined aerogel(FGA)have an obvious improvement in the adsorption of GA to n-hexane and xylene.GA-T performs well in offshore oil spill treatment and show a good application prospect.FGA/S composite materials were prepared by the the framework of FGA with the sublimation sulfur as the main body.Using FGA/S as the positive electrode material for lithium-sulfur batteries,with a current carrying capacity of 60 wt%,the battery was assembled to test its electrochemical performance.It was found that the first-cycle specific capacity of lithium-sulfur batteries reached 654mAhg-1 at 0.5C.Compared with GA/S cathode,FGA/S cathode batteries was improved to varying degrees in the cycle performance,coulombic efficiency,and rate performance.It can be seen from the cyclic voltammetry test and impedance test that the introduction of FGA not only improves the conductivity of the sulfur cathode,but also provides more reaction sites and electron transmission channels.更多还原