Ab Initio Molecular Dynamics Study on the Interlayer Bonding of Few-Layer Graphene under Pressures

Studying the formation of diamane through simulation is crucial for exploring the synthesis of ultrathin diamond films with excellent physical properties. However, dynamic studies of the phase transition from few-layer graphene to diamane under pressures using ab initio molecular dynamics (AIMD) and investigations on the corresponding evolution of the electronic structure have not yet been reported. In this study, we combined AIMD with static electronic calculations to explore the geometric and electronic structure evolution of bilayer graphene under different pressure-transmitting media (PTM). It is found that the pressure required for surface functionalization of bilayer graphene decreases in the order of halogens, hydrogen, hydrogen halides, and hydroxyl-containing systems, attributed to their different affinity for charge transfer to graphene. Additionally, as the number of graphene layers increases, the surface functionalization becomes easier under most PTM, especially in hydrogen-, hydrogen halide-, and hydroxyl-containing systems. Our research provides valuable insight into a deeper theoretical understanding of the interlayer bonding mechanism, offering potential for the experimental fabrication of diamane.