Deposition of carbon-based materials directly on copper foil and nickel foam as 2D-and 3D-networked metal substrates by in-liquid plasma

In-liquid plasma (ILP) process has been an attractive route for nanomaterial synthesis due to its high-yield production in low-temperature atmospheric pressure conditions. In comparison with conventional ILP synthesis that produces free-standing nanomaterials, this work brings a new perspective on the application of the ILP process through carbon formation directly on ethanol-immersed two-dimensional (foil) and three-dimensional (3D) (foam) metal substrates. Three types of carbon, including graphene, graphitic carbon, and amorphous carbon, were simultaneously produced during plasma discharge. Graphitic and amorphous carbon formed radially and coexisted on the metal substrate surface, while free-standing graphene was produced in ethanol. A conformal coating was achieved on the exterior surface of the 3D-networked substrate. The proposed mechanism for carbon formation on metal substrates is presented here.