Three-dimensional bulk reduced graphene oxide coatings with strong metal adhesion via cold plasma and pulsed current

Both graphene, a single-atom-thick layer, and its derivative, reduced graphene oxide (rGO), are highly promising materials with a wide range of applications due to their exceptional mechanical, electrical, and thermal properties. However, the application of graphene in its natural form in engineering practice is challenging, which is why a three-dimensional structure is preferred. Additionally, a very strong bond with the metal substrate is highly desirable. Here, we present a method for obtaining such micrometer-thick 3D rGO coatings on various metal alloys. This bulk material coating inherits, to some extent, the exceptional properties of single-layer graphene. The method for obtaining 3D rGO is based on the preliminary preparation of the metal surface using an argon cold plasma and the application of rGO using a pulsed electric current. A good bond between the layer and the substrate has been demonstrated, confirmed both by TEM, where no porosity was found, and in a number of other studies, including XPS, nanoindentation, and scratch testing. To better determine the quality of the obtained bond with the substrate, a resistance measurement method was used during tensile-compression tests. The 3D rGO coating developed can be used in many practical engineering applications where the high strength or other remarkable properties of graphene are particularly desirable.