The influences of internal interactions and functional groups on the adsorption of graphene and graphene oxide with alumina substrate

Molecular dynamics is used to simulate the adsorption process of graphene and graphene oxide fragments with different sizes on the (0001) crystal plane of Al 2 O 3 . The results reveal that the influence of internal interaction and functional groups on graphene and graphene oxide adsorbed by the alumina surface. From the atomic simulation, it can be found that the Coulomb interaction between graphene and the substrate can enhance the interaction between graphene oxide and the substrate after oxidation. It also promotes the spontaneous adsorption of graphene oxide to the substrate, and its influence on the process is much greater than that of the van der Waals force interaction. Before graphene was oxidized, the Coulomb interaction and van der Waals force interaction inhibited the desorption of graphene, but the Coulomb interaction was relatively weak. In addition, the increase of the size of graphene and graphene oxide can reduce the adhesion energy and desorption free energy, resulting in the instability of adsorption state, which is more unfavorable to the occurrence of the adsorption process. In graphene oxide, the oxidized carbon atom bears most of the potential energy and induces the instability of the structure. Its three functional groups, carboxyl, hydroxyl and epoxy, play a role in reducing the overall potential energy of graphene oxide and stabilizing the structure of graphene. Therefore, compared with pristine graphene, graphene oxide with a high degree of oxidation can form a much stable coating on the alumina substrate. By means of multiscale modelling and simulation, this article may theoretically contribute to the application of graphene coating on the aluminum alloy surface and gives guiding opinions for enhancing the strength of graphene coating.