Rotation induced symmetry change of friction coefficient of water on graphene/h-BN heterostructures

Abstract

The graphene/h-BN heterostructure provides a promising device for biomedical applications and biosensor. However, the friction characteristics of water on graphene/h-BN are still elusive. By means of molecular dynamics simulations, we investigated the friction coefficient of water on both sides of graphene/h-BN heterostructures under various rotation angle, which shows a non-monotonic but symmetrical variation with relative interlayer angle. Despite that friction coefficient of h-BN surface is larger than that of graphene, as the rotation angle increases, the friction coefficient of water on both sides of the graphene/h-BN heterostructure exhibits the same “M”-shaped curve. The center of symmetry of the curve is at the rotation angle of 30°; the friction coefficient is the largest when the rotation angle is 10° and 50°. It was found that graphene/h-BN heterostructure is a device whose friction coefficient is different on both sides and can be adjusted by twisting the relative interlayer angle. These results could be demonstrated by the van der Waals interaction and different pattern of free energy landscape. These findings provide detailed insights into the mechanism of the friction property of water at nanoscale, which would facilitate feasible applications of graphene/h-BN heterostructure in biosensor and biomedicine.