A Study of Ultra-Low Friction in Two-Dimensional Materials using Density-Functional Theory

Abstract

Overcoming friction in any mechanical system is a universal problem in many aspects of engineering and nanotechnology. Being a dissipative force, friction reduces the efficiency of the system while adding unwanted heat and introducing wear between the surfaces in contact. Solid lubricants have attracted increasing attention in recent years and are starting to gain preference over petroleum-based lubricants because of their biodegradable properties and high-temperature tolerance, which makes them ideal candidates for clean technologies, aviation, aerospace, and defense-related applications. In this thesis, a unique, ultra-low frictional property in two-dimensional (2D) materials, known as structural superlubricity, has been theoretically investigated. Superlubricity has been experimentally observed in a wide range of 2D materials, including graphene, molybdenum disulfide (MoS2), hexagonal boron nitride (h-BN). Herein, a detailed analysis of friction in commensurate, and structurally incommensurate, bilayer graphene, h-BN, MoS2, and a novel material blue phosphorene, has been executed using dispersion-corrected density-functional theory (DFT).