Effect of hydrogen concentration on the friction evolution mechanism of few-layer graphene: A molecular dynamics study in nanoscratch processes

Abstract

This article explored the friction evolution mechanism of graphene under different hydrogen concentrations and scratch depths based on molecular dynamics. In a vacuum, graphene exhibits excellent frictional properties when the scratch depth is less than the layer distance of graphene. However, as the depth increases, the diamond tip contacts more CC bonds, and the phenomenon of fracture and recombination of CC bonds in the graphene layer intensifies, increasing surface friction. In a low concentration of hydrogen environment, compared with the friction in a vacuum, it increases due to the interlocking effect of the protruding hydrogen atoms on the diamond tip and the scratch path. As the concentration of the hydrogen environment increases, the friction force does not increase monotonically. In addition, in a hydrogen environment, the stability of the planar structure of graphene will be weakened, thereby affecting the wrinkling effect and wear path.