Preparation And Properties Of Graphene Based Nanostructures And Nanocomposites

In this paper, we theoretically and experimentally studied the applications of graphene innanostructures and polymer nanocomposites.It is demonstrated using molecular dynamics (MD) simulations that P-doped siliconnanowires (Si NWs) can activate graphenes self-scrolling onto Si NWs and thus produce newkinds of graphene nanoscroll (NS)/Si core/shell heterojunctions. The simulations show thatgraphene sheets can fully self-scroll onto SiNWs whenthe Si NW radius is larger than athreshold of about5, forming a stable core/shell structure. It is the van der Waals force thatplays a primary role in the self-scrolling process. The configuration of the graphene/Siheterojunction depends significantly on the diameter of the Si NWs. The final NS becomesmultiwalled with increasing graphene length when the diameter of the SiNWs is larger than athreshold of about6. The zigzagNS is proved to be themost stable, while the chiralNSs areunstable and tend to evolve into zigzag NS and a model is set up to interpret the tendency fromthe standpoint of bond. It is demonstrated that the graphene width has no influence on theself-scrolling process at all. The uniquestructure of the graphene/Si core/shell heterojunctionswill significantly enhance their applications in nanoelectronic devices, hydrogen storage, solarcells, chemical or biological sensors, and energy storage in supercapacitors or batteries.A novel sandwich structure based on few-layer graphene nanosheets (FLGs) composed offunctionalized porous graphene, pristine graphene and functionalized porous graphene isproposed. After one-step alkaline-mediated hydrothermal treatment, the outmost layers of FLGsare etched to porous structure. Sandwich FLGs/poly (vinylidene fluoride)(PVDF) compositesare fabricated and the composites show the best dielectric properties among carbon-basedfillers/PVDF composites. Owing to the unique semiconductor/conductor/semiconductorstructure, theoretical analysis indicates that the dielectric constant of the sandwich FLGs/PVDF composites can be even higher.