Preparation And Application Of Graphene Aerogels By Soft Template

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.