Characterization of graphene nanoplatelets prepared from polyimide-derived graphite

Multi-layered graphene platelets with tens of micrometer-wide were prepared from graphitized polyimide film by graphite intercalation compound (GIC) via exfoliation process. Sulfuric acid was used in the GIC formation step as the functional intercalating agent. Raman spectroscopy revealed that pristine graphitized polyimide film had the minimal intensity of D band peak with negligible R ratio value (ID/IG=0.01), while natural graphite flakes possessed much higher R ratio (ID/IG=0.104) due to their relatively high D band peak intensity. Exfoliated graphene platelets prepared from the graphitized polyimide film were analyzed to have the averaged lateral size of 42 μm at the thickness of 5 nm. Graphene platelets produced from natural graphite flakes were, however, found to be smaller (average lateral size of 30 μm) and more defective than the product derived from graphitized polyimide film. This implies the intrinsic graphitic defect of starting materials is substantially related to the properties of the graphene platelets prepared thereof.