▎ 摘　　要

Herein, we introduced surface modification of a Cu catalyst by employing CH4 pre-annealing, which changed the uniformly rough Cu surface; this resulted in formation of high-quality and uniform Bernal-stacked bilayer graphene as well as monolayer graphene due to controlled synthesis time. A well-designed Cu surface was developed for synthesis of bilayer graphene with high coverage (>95%) and a high Bernal-stacking ratio (similar to 99%). Dual-gated transistors of Bernal-stacked bilayer graphene showed typical tunable transfer characteristics under varying gate voltages with carrier mobilities of 1000-2000 cm(2) V-1 s(-1). Through density functional theory calculations, we demonstrated that a uniformly rough Cu surface is favorable for synthesis of Bernal-stacked bilayer graphene. Finally, we employed bilayer graphene as a perfect diffusion barrier facilitated by complementing the diffusion pathway of numerous grain boundaries in graphene.