Graphene coatings: An efficient protection from oxidation

TL;DR

This paper shows that graphene coatings effectively prevent oxidation by creating a high energy barrier, with bilayer graphene offering enhanced protection, and provides insights from first-principles calculations to guide nanocoating development.

Contribution

It presents a detailed first-principles analysis of how graphene and bilayer graphene act as oxidation barriers, highlighting the effects of vacancies and edge sites on protection efficiency.

Findings

Graphene coating creates a high energy barrier against oxygen penetration.

Bilayer graphene offers superior oxidation protection compared to monolayer.

Vacancies and edges reduce the protective barrier by facilitating oxygen dissociation.

Abstract

We demonstrate that graphene coating can provide an efficient protection from oxidation by posing a high energy barrier to the path of oxygen atom, which could have penetrated from the top of graphene to the reactive surface underneath. Graphene bilayer, which blocks the diffusion of oxygen with a relatively higher energy barrier provides even better protection from oxidation. While an oxygen molecule is weakly bound to bare graphene surface and hence becomes rather inactive, it can easily dissociates into two oxygen atoms adsorbed to low coordinated carbon atoms at the edges of a vacancy. For these oxygen atoms the oxidation barrier is reduced and hence the protection from oxidation provided by graphene coatings is weakened. Our predictions obtained from the state of the art first-principles calculations of electronic structure, phonon density of states and reaction path will unravel how a graphene can be used as a corrosion resistant coating and guide further studies aiming at developing more efficient nanocoatings.