Study On Preparation And Properties Of Multifunctional Graphene Aerogel

The graphene aerogels hold the excellent properties of graphene sheets and aerogels.Althrough a great deal of studies on fabricating graphene aerogels and their hybrid materials,there still remain many shortcomings about the preparation of graphene aerogels and the properties of hybrid graphene aerogels.Therefore,this paper mainly focuses on modifying the shortcomings,the substratal analysis and discussion using various characterization methods.Three main aspects of this paper are as follows:Ultralight graphene/cellulose nanocrystal(CNC)hybrid aerogels(GCHAs)were prepared via an integration strategy of a two-step reduction process and ambient drying technology.Such a preparation strategy makes the as-prepared GCHAs circumvent an issue of structural collapse induced by shrinkage in an ordinary ambient drying process.GCHAs have three-dimensional large cellular structure with CNCs sandwiched in graphene flakes.Incorporation of stiff rod-like CNCs in a flexible graphene aerogel(GA)realized the multifunction of hybrid GA materials.With increase of CNCs loading,the modulus of GCHAs enhanced obviously.The mechanical strength of GCHAs could be adjusted by the CNCs loading.The sorption experiments of both organic solvents and water on the GCHAs were carried out and GCHAs presented good amphiphilic absorption capacity.The work provides a promising amphiphilic graphene-based aerogel material with tunable mechanical strength by a facile,economic and environmentally-friendly approach,giving it high potential for use in waste water treatment and pressure sensitive materials.Second,this part studies the fabrication of graphene/chitin nanofiber hybrid nanocomposite.The results show that the chitin nanofiber prepared by Tempo oxidation can be hybrided with graphene sheets,while the specific surface areas of as prepared carbon aerogels are a bit small.The deacetylated chitin nanofiber can be compounded with the hybrid graphene aerogels containing 20 wt.% CNCs,and the composite aerogels exhibit dual network architecture.The carbonized as-prepared hybrid graphene aerogels by high temperature can be used as supercapacitor and they exhibited excellent stability based on the CV curves.They can remain good shape at 500mv/s,indicating the potential application in supercapacitor.Third,we fabricated the pure ultralight and super resistance to fatigue graphene aerogels tamplated by air bubble via a green and ambient drying technology,whose lowest density reaches to 2.4mg/cm3.Compared to previous method,the as prepared graphene aerogels present more uniform and smaller holes(300 ?m)with thinner walls.Their densities and hole walls can be tuned by the speed of strring and the concentration of GO.Besides,the resulting graphene aerogels can keep their original volume compressed for one million times at 70%,revealing the super resistance to fatigure.It is expected that this approach can achieve the industrial production of graphene aerogels,and further expand the practical application field of graphene aerogels.