Atomistic modelling of friction of Cu and Au nanoparticles adsorbed on graphene

TL;DR

This study uses classical molecular dynamics to investigate how copper and gold nanoparticles interact with graphene, revealing material-dependent friction behaviors and a linear relationship between friction force and contact area.

Contribution

The paper introduces a detailed atomistic simulation approach to compare frictional behaviors of Cu and Au nanoparticles on graphene, highlighting material-specific interactions.

Findings

Friction force increases linearly with contact area for Au nanoparticles.

Friction force exhibits a sawtooth time dependence due to local commensurability.

A qualitative model explains the observed frictional behaviors.

Abstract

We present classical molecular dynamics calculations of the behavior of copper and gold nanoparticles on a graphene sheet, sheared with a constant applied force $F_{\rm a}$. The force $F_{\rm s}$ acting on the particle from the substrate depends on the material of the nanoparticles (Au or Cu), and exhibits a sawtooth dependency on time, which we attribute to local commensurability between the metal nanoparticle surface atomic positions with the graphene lattice. The time-averaged value of $F_{\rm s}$ (the friction force) acting on Au nanoparticles increases linearly with the contact area, having slopes close to the experimentally observable ones. A qualitative model is proposed to explain the observed results.