Study On The Preparation And Properties Of Silver, Copper Or Bismuth Containing Graphene Composites

Natural flake graphite has been widely used in different fields and its derivativeshave excellent performances. Graphene, which can be exfoliated from graphite，is anew carbon nanomaterial and is of great interest owing to its unique electronic, optical,mechanical, and thermal properties. The discovery of graphene is opening up a newresearch area for condensed-matter physics, materials science, and benefitinghigh-dielectric-constant materials. This paper focused on the graphene composites andtheir properties. Emphasis was placed on preparation, modification of graphene andthe dielectric and photocatalysis properties of its composites.First, the preparation process of graphene is studied and optimized. Grapheneoxide (GO) prepared with direct oxidation and pre-oxidationsuper respectively, isreduced by different reductants. The reduced products are characterized by scanningelectron microscopy, transmission electron microscopy, infrared spectroscopy, atomicforce microscope and X-ray diffraction. Results indicated that the GO prepared withpre-oxidationsuper presented larger oxidation degree, and the graphene which wasreduced by hydrazine hydrate showed highest conductivity (1.11×103s/cm).Secondly, sliver-loaded graphene composite where graphene was modified by Agnanoparticles was prepared, and then the sliver-loaded graphene/PI composites werefabricated by in-situ polymerization. As a contrast, graphene/PI composites, withgraphene as the filler and PI as the matrix, were fabricated by in-situ polymerization.The relationships between effects of sliver-loaded graphene or graphene volume anddispersion on dielectric properties of composites were discussed. Results indicatedthat graphene and sliver-loaded graphene were oriented to a certain extent in PI. Ahigh dielectric constant of13.87(100Hz) was obtained when the concentration ofgraphene was0.9vol%. The percolation threshold of sliver-loaded graphene/PInanocomposites was fc=1.07vol%, and when volume fraction of grapheme reachedthe percolation threshold, dielectric constant of sliver-loaded graphene/PI compositewas8.91(100Hz).Finally, cuprous oxide and bismuth phosphate loaded on reduced grapheme oxidewere prepared respectively by the method of sedimentation-reduction andhydrothermal synthesysis. The microstructure and properties of both composites werestudied. The addition of reduced graphene oxide changed the microstructure ofcuprous oxide, and the form of bismuth phosphate crystal was also affected. The photocatalytic research results of composites showed that the photocatalyticdegradation of red water could reach42.6%by Cu2O/rG composite, and the dye MBcould be effectively photocatalytically degraded by BiPO4/rG composite.