Diffusion, Nucleation, and Self-Optimization in the Forming Process of Graphene in Annealed Nickel–Carbon Alloy

Abstract

Reactive molecular dynamics simulation is used to explore the forming mechanism of graphene in an annealed nickel–carbon alloy. Results show that after internal carbon atoms diffuse to the surface of the alloy spontaneously with a large diffusion coefficient, graphene nuclei are formed due to the catalysis of nickel atoms. The nuclei can grow into large graphene and then the large graphene optimizes itself when annealing time is sufficient, accompanied by some nickel–carbon compounds and unstable nickel clusters in this alloy. The substrate, carbon concentration, annealing temperature, and alloy thickness could affect the morphology of the obtained graphene. Our simulation provides insight into the structural evolution of annealed nickel–carbon alloys at the atomistic level and will be valuable to the preparation of graphene.