Structural superlubricity in graphene/GaSe van der Waals heterostructure

Two-dimensional layered materials arise enormous research enthusiasm for achieving superlubricity. We theoretically study the atomic friction behaviors of the heterogeneous graphene/GaSe bilayer system under normal load and defect/functionalization effects through first-principles methods. The heterogeneous graphene/GaSe exhibits much lower friction and shear strength than the homogeneous graphene/graphene and GaSe/GaSe, and the introduced OH-functionalized graphene can further reduce the friction. The ultralow friction coefficients of 0.0033∼0.080 indicate the heterogeneous graphene/GaSe is a promising solid lubricant with superlubricity. The larger electrostatic repulsion caused by the incommensurate interface of the heterogeneous bilayer system and the less variation of the charge density differences along the whole sliding is responsible for the lower friction.