Enhanced chemical reactions of oxygen at grain boundaries in polycrystalline graphene

Oxygen adatoms on graphene and their potential reactions have been studied extensively as a way to modify and control the material’s properties. Here, we report first-principles calculations and Kinetic Monte Carlo simulations to describe oxygen binding, diffusion, and reactions on graphene in the presence of grain boundaries. We show that the defects attract and accumulate oxygen caused by the local strain. Moreover, we find that the reaction of a three-atom oxygen cluster, which consumes carbon atoms and creates vacancies in graphene, has a lower reaction barrier at grain boundaries than that on pristine graphene. Kinetic Monte Carlo simulations suggest that the dynamics of oxygen on graphene is controlled by two processes, oxygen reaction and migration, which depend on temperature and oxygen coverage. Because of the comparable activation barrier for both processes, etching at grain boundaries and the pristine region occurs simultaneously.

Density functional calculations and Kinetic Monte Carlo simulations have been performed to describe oxygen binding, diffusion, and reactions on graphene in the presence of grain boundaries. Because of the local tensile strain, the binding of oxygen to graphene is enhanced, the migration is suppressed, and reaction barrier of oxygen clusters decreases at grain boundaries. KMC simulations suggest that two processes, oxygen migration and reaction, control the dynamics of oxygen on graphene.Figure optionsDownload as PowerPoint slide