Friction characteristics in graphene/MoS2 heterojunction

• The size and twist angle of the slider invert the interlayer potential surface • Steady-state configuration determines the corrugated or linear motion of the flake • The incommensurate friction is about 100 times less than commensurate friction • The friction on the left and right sides of the contact edge cancel each other out • The maximum friction occurs when the edge is perpendicular to sliding direction The weak interlayer interaction and strong intralayer bonding in two-dimensional (2D) lamellar materials give rise to ultra-low friction properties when the contacted interface between two crystalline is incommensurate, known as structural superlubricity. The origin of friction in a two-dimensional heterojunction is complicated by the interplay among normal forces, edge effects and twist angle ( θ ). In this article, molecular dynamics (MD) has been adopted to theoretically investigate the friction characteristics in graphene/MoS 2 layered heterojunction. The results demonstrate that friction of graphene/MoS 2 interface at θ = 0° is approximately 100 times larger than the one at θ = 30°. Unexpectedly, whether graphene slider experiences in-plane vibrational motion perpendicular to the sliding path depends on the initial configuration and relative twist angle. To quantitatively understand the origin of friction, the friction contributions from different edge atoms and internal atoms have been investigated. It is found that friction of the edge perpendicular to the sliding direction is much larger than that of the other edges. In addition, friction from the front and back edges mostly cancels out at twist angles θ = 0° and 30°.