Study on Preparation of Graphene Material via Microwave Assisted Intercalation Exfoliation Method and Its Application
Supervisor:song li zuo yu yun
Graphene,a perfect monolayer of carbon atoms arranged into a two-dimensional(2D)honeycomb lattice,has attracted tremendous attention in recent years.Graphene has unique physical and chemical properties,including hydrophobicity,high specific surface area and quantum Hall effect.In this dissertation,graphene has been prepared for the first time via microwave assisted intercalation-exfoliation of graphite.The influences of process parameters on the structure and performance of graphene have been systematically investigated.Then graphene films were coated on glass substrate and melamine foam,and the effects of technological parameters on the hydrophobicity have also been systematically studied.Finally,the hydrophilic and the hydrophobic graphene composite membranes were prepared respectively by modifing graphene with nano titania.Based on the work mentioned above,super-hydrophobic graphene foam and hydrophilic modified alumina microfiltration membrane were successfully obtained.It is found that:(1)The mechanism of microwave expanding graphite is systematically studied for the first time.The results show that microwave radiation can increase both the disorder degree and the interplanar distance of graphite.(2)Ammonia is innovatively utilized as the intercalating agent for graphene preparation,and the intercalation mechanism is also systematically investigated.C=N bond between graphite and ammonia is conductive to the intercalation of ammonia to graphite.Compared with ethylene diamine and diethanolamine,the molecular diameter and steric hindrance of the ammonia is more appropriate for the size in the “wedge” model.Thus,ammonia is a good intercalation agent for the intercalation exfoliation of graphite to prepare graphene.Few-layer graphene with the thickness of about 2.3 nm and 3-8 layers is obtained with the optimization process parameters.(3)Graphene film with excellent hydrophobicity is coated on hydrophilic porous melamine foam via optimized process parameters,and its water wetting angle reaches to 166°.Graphene can combine strongly with the melamine in the form of C-H,C=C and C-N bonds.(4)Super-hydrophobic composite film is designed and prepared via the dopping of nano titania sol to graphene.A “Lotus leaf” microstructure of nano titania with the size of 50 nm has been obtained on the surface of graphene.This special complex structure achieves the superhydrophobic surface,and its wetting angle is up to 171°。(5)The commercial alumina microfiltration membrane has been modified by graphene-titania composite material,which has excellent visible photocatalytic activity and hydrophilic properties.By this modification,the wetting angle of modified alumina membrane reduces from the original 21.7° to 9.8°,resulting in the increase of permeation flux by 36.8%,and the oil rejection is also improved to 98.7%.