Indirect interactions of metal nanoparticles through graphene

We employ ultra-high vacuum electron microscopy to investigate the interaction of metal nanoparticles through graphene. The nanoparticles attract those on the other side of graphene in the systems of Ag/graphene/Ag and Cu/graphene/Cu. In contrast, the system of Au/graphene/Au manifests the repelling interaction. Our density functional theory calculations demonstrate that for lower electron-affinity metals such as Cu and Ag, the clusters on opposite sides of graphene prefer the same site to share the electron-loss and reduce the energy. While for higher electron-affinity metals such as Au, they prefer to stay away from the clusters on the other side of graphene.