Gold in graphene: In-plane adsorption and diffusion

We study the bonding and diffusion of Au in graphene vacancies using density-functional theory. Energetics show that Au adsorbs preferably to double vacancies, steadily in-plane with graphene. All diffusion barriers for the complex of Au in double vacancy are above 4 eV, whereas the barriers for larger vacancies are below 2 eV. Our results support the main results of a recent experiment [ Y. Gan , Small 4 , 587 ( 2008 ) ] but suggest that the observed diffusion mechanism is not thermally activated but radiation enhanced.