Session: Physical Chemistry Poster:

The superior lubrication capabilities of two-dimensional crystalline materials such as graphene, hexagonal boron nitride (h-BN), and molybdenum disulfide (MoS₂) have been well known for many years. It is generally accepted that superlubricity in these materials is due to the misalignment of the surfaces in contact, known as incommensurability. However, recent studies using molecular dynamics simulations have demonstrated that incommensurability is not a requirement for the superlubric behavior in MoS₂. In this light, we present a detailed analysis of friction in various commensurate structures of bilayer graphene, h-BN, MoS₂, and the novel blue phosphorene using dispersion-corrected density-functional theory. For each material, the interaction energies between two adjacent layers, with one layer sliding atop the other, have been computed and the corresponding potential energy surfaces plotted. We have considered rotational angles of 0^o, 21.79^o, 32.20^o and, 13.17^o, and computed the rotational barriers for each case. We present an innate relationship between rotational barriers, interaction energy, and ultra-low frictional properties in these materials.

Dr. Erin R. Johnson

Professor, Dalhousie University

Appearances