Friction at the homogenous and heterogenous interfaces of penta-graphene and B₂N₄

This study is to examine the effectiveness of the two ways forming the incommensurate contacts on reducing friction. Two dimensional (2D) penta-graphene (PG) and B₂N₄ possessing the same lattice structure and excellent lubricating property were chosen to construct the homogenous and heterogenous interfaces. We studied the frictional properties at the homogenous interfaces of PG/PG and B₂N₄/B₂N₄, and the heterogenous interface of B₂N₄/PG. Our calculations show that the friction coefficients at the homogenous interface of B₂N₄/B₂N₄ are smaller than those at the heterogenous interface of B₂N₄/PG. The different compositional elements at the commensurate contacting surfaces hardly reduce the interlayer friction. It indicates the ineffectiveness of heterogenous interface on reducing friction when it is commensurate contacting. Additionally, the incommensurate contact formed via biaxial stretching one layer can significantly reduce the interlayer friction, which is the superposition of uniaxial stretching. In addition, the interlayer friction was elucidated from the point views of potential energy, charge density difference and registry index (RI). This study highlights the importance and effectiveness of twisting in reducing the interlayer friction compared to stretching.