Arrays of Ru nanoclusters with narrow size distribution templated by monolayer graphene on Ru

► Ru nanoclusters self-assemble on monolayer graphene (MLG) on Ru(0001). ► MLG/Ru(0001) moiré templates small monodisperse Ru clusters over macroscopic areas. ► The preferred binding site of the Ru clusters is the low fcc region of the moiré. ► Ru clusters on strongly coupled MLG/Ru(0001) cause local lifting of the MLG layer. ► Ru clusters grow larger when MLG-support coupling is weakened (O2 intercalation).