A grain boundary regulates the friction behaviors between graphene and a gold substrate

The nanofriction of graphene is critical for its broad applications as a lubricant and in flexible electronics. Herein, using a Au substrate as an example, we have investigated the effect of the grain boundary on the nanofriction of graphene by means of molecular dynamics simulations. We have systematically examined the coupling effects of the grain boundary with different mechanical pressures, velocities, temperatures, contact areas, and relative rotation angles on nanofriction. It is revealed that grain boundaries could reduce the friction between graphene and the gold substrate with a small deformation of the latter. Large lateral forces were observed under severe deformation around the grain boundary. The fluctuation of lateral forces was bigger on surfaces with grain boundaries than that on single-crystal surfaces. Friction forces induced by the armchair grain boundaries was smaller than those by the zigzag grain boundaries.