Free-Standing Single-Atom-Thick Iron Membranes Suspended in Graphene Pores

Iron in Graphene Carbon or other covalently bonded materials, like boron nitride, can form two-dimensional sheets because of the strong bonding between the atoms. In contrast, metals share electrons in a three-dimensional delocalized way, and this could preclude the formation of thin stable sheets. Nevertheless, Zhao et al. (p. 1228 ) observed pure iron membranes suspended across the pores in a graphene sheet. This phenomenon was discovered when an iron chloride solution, used to process the graphene, decomposed to form pure iron films across the pores.