  Monatomic metal (e.g. silver) structures could form preferably at graphene
edges. We explore their structural and electronic properties by performing
density functional theory based first-principles calculations. The results show
that cohesion between metal atoms, as well as electronic coupling between metal
atoms and graphene edges offer remarkable structural stability of the hybrid.
We find that the outstanding mechanical properties of graphene allow tunable
properties of the metal monatomic structures by straining the structure. The
concept is extended to metal rings and helices that form at open ends of carbon
nanotubes and edges of twisted graphene ribbons. These findings demostrate the
role of graphene edges as an efficient one-dimensional template for
low-dimensional metal structures that are mechanotunable.
