Tuning adlayer-substrate interactions of graphene/h-BN heterostructures on Cu(111)-Ni and Ni(111)-Cu surface alloys.

The evolution of the interface and interaction of h-BN and graphene/h-BN (Gr/h-BN) on Cu(111)-Ni and Ni(111)-Cu surface alloys versus the Ni/Cu atomic percentage on the alloy surface were comparatively studied by the DFT-D2 method, including the critical long-range van der Waals forces. Our results showed that the interaction strength and interface distance of Gr/h-BN/metal can be distinctly tuned by regulating the chemical composition of the surface alloy at the interface. The initially weak interaction of h-BN/Cu(111)-Ni increased linearly with increasing Ni atomic percentage, and the interface distances decreased from ∼3.10 to ∼2.10 Å. For the h-BN/Ni(111)-Cu interface, the strong interaction of the N top B fcc/hcp stacking decreased sharply with increasing Cu atomic percentage from 0% to 50%, and the interface distances increased from ∼2.15 to ∼3.00 Å; meanwhile, the weak interaction of the B top N fcc/hcp stacking decreased slightly with increasing Cu atomic percentage. The absorption of graphene on h-BN/Cu(111)-Ni with B top N hollow /N top B fcc and B top N hollow /B top N fcc stacking was more energetically favorable than that with N top B hollow /N top B fcc and N top B hollow /B top N fcc at Ni atomic percentages under 75%, while the interaction energy of graphene on h-BN/Cu(111)-Ni increased sharply at Ni atomic percentages higher than 75% for the B top N hollow /N top B fcc and N top B hollow /N top B fcc stacking. In contrast, the interaction between graphene and the h-BN/Ni(111)-Cu surface increased sharply at Cu atomic percentages lower than 25% and decreased sharply at Cu atomic percentages higher than 75%. The interaction energies were higher when the percentage of Cu atom was between 25% and 75%. The analysis of charge transfer and density of states provided further details on the changing character and evolution trends of the interactions among graphene, h-BN, and Cu-Ni surface alloy versus the Ni/Cu atomic percentage.