A nanotube-graphene hybrid film and method for forming a cleaned nanotube-graphene hybrid film. A method includes depositing nanotube film over a metal foil to produce a layer of nanotube film, placing the metal foil with as-deposited nanotube film in a chemical vapor deposition furnace to grow graphene on the nanotube film to form a nanotube-graphene hybrid film, and transferring the nanotube-graphene hybrid film over a substrate.

Disclosed herein is a preparation method of graphene, capable of preparing graphene having a smaller thickness and a large area, and with reduced defect generation, by a simplified process. The preparation method of graphene includes forming dispersion including a carbon-based material including unoxidized graphite, and a dispersant; and continuously passing the dispersion through a high pressure homogenizer including an inlet, an outlet, and a micro-channel for connection between the inlet and the outlet, having a diameter in a micrometer scale, wherein the carbon-based material is exfoliated, as the material is passed through the micro-channel under application of a shear force, thereby forming graphene having a thickness in nanoscale.

Described herein are hybrid nanomaterials that can include a functionalized nanodiamond and a functionalized graphene and/or functionalized graphene oxide. Also described herein are composite materials that can include a hybrid nanomaterial described herein and a polymer or polymeric material. Also described herein are methods of making and using the hybrid nanomaterials and composite materials described herein.

Hybrid nanomaterials that can include a functionalized nanodiamond and a functionalized graphene and/or functionalized graphene oxide. Composite materials that can include a hybrid nanomaterial described herein and a polymer or polymeric material. Methods of making and using the hybrid nanomaterials and composite materials described herein.