Ultralow Friction in Graphene Multilayers with Amorphous Carbon Interlayers

Amorphous carbon layers (ACLs) have been experimentally realized as a two-dimensional carbon material, but their influence on sliding in graphene multilayers is still unclear. In this study, molecular dynamics simulations were carried out for pristine graphene (PG) multilayers and graphene/amorphous-carbon (AG) multilayers under normal pressures of 0.1, 1, and 10 GPa. Both models show ultralow friction. The coefficient of friction (COF) decreases with increasing pressure because the friction force increases much more slowly than the normal force. AG has lower COF than PG at all pressures, with reductions of about 60%, 54%, and 26%, respectively. Layer displacement and interlayer sliding analyses show that shear in PG is transferred through several graphene/graphene interfaces, whereas relative sliding in AG is mainly located near the ACLs. Under high pressure, the ACLs become flatter, which may help stabilize local sliding. These results suggest that amorphous carbon interlayers may modify shear transfer and facilitate ultralow-friction sliding in graphene-based multilayers under the present simulation conditions.