Density Functional Theory Study of Metal Adatoms at or Near a Stone-wales Defect in Graphene

Research interest of small clusters of the transition metals continues to grow given their wide range of applications. In recent years, graphene with vacancy and structural defects have attracted increasing attention due to the fact that manufactured graphene is often not pristine, and crystal defects are considered useful in the context of modifying and engineering the band structure of graphene, hence altering both its physical and chemical properties significantly. Previous studies done on the Stone-Wales defect shows that C–C bonds associated with Stone-Wales defects are more reactive than the case for a perfect hexagon. In this work, we investigated the structural, electronic and magnetic properties of Co, Rh and Ir adatoms and dimers in various configurations adsorbed on a graphene sheet with a Stone-Wales transformation. We are interested in the change in bonding and the change in electronic and magnetic properties as a result of the presence of the metal adatom near the Stone-Wales defect by comparison to previous work done where the adatom was adsorbed on graphene with no defects. The results of this work will impact our view on the application of small metal clusters adsorbed on defected or non-defected graphene. Our results show that the Stone-Wales defect significantly increased the adsorption energy by 0.32 eV of a Co atom positioned at the hole site of a 6-carbon ring but the magnetic moment showed no significant change. Hence, the Stone-Wales defect could be used to significantly alter the stability of the adsorption of adatoms on graphene.