Formation of a wave structure on the surface of a graphene film

A wavy structure of the surface of graphene nanoparticles on a hydrocarbon substrate has been obtained. It has been shown that the wavy surface is the manifestation of the Kelvin–Helmholtz instability at the interface between liquid paraffin and graphene suspension with the inhomogeneity length $\lambda = 250$ nm. The manifestation of such wavy structures is due primarily to van der Waals forces.