Plasma Jet-Assisted Synthesis of Graphene Using a DC Plasma Torch

Conditions of substrate-free syntheses of graphene and graphene-based systems based on conversion of liquid and gaseous carbon precursors in helium, nitrogen, and argon plasma jets generated by a dc plasma torch at a reduced pressure are investigated. Using a number of physical characterization techniques, it is shown that bulk-synthesized (i.e., substrate-free) graphene has the morphology of crumpled paper. By changing the geometry of the flow-through section of the reactor, without using substrates, hydrogenated graphene structures are synthesized. Nitrogen- or copper-doped graphene can be prepared using nitrogen plasma. Thermally stable graphene oxide is obtained by introducing alcohols into argon or helium plasmas. It is concluded that graphene materials can be prepared by the plasma-assisted one-step syntheses.