Fig. 1: Synthesis and structural characterization of element-doped porous graphene superlattice.

a Schematic representation of the synthesis process for graphene superlattice. The process to create element-doped graphene superlattice involves growing iron oxide nanoparticles on graphene, followed by carbon etching, nanoparticle removal with hydrochloric acid, and element doping of the graphene superlattice. b–e Transmission electron micrographs showing (b) monolayer graphene sublattice with monodisperse square-shaped nanopores and (c–e) bilayer graphene superlattice with partially overlapped square nanopore. The top and bottom layers in the graphene superlattice in (e) are distinguished in red and green, respectively. f The periodic arrangement of carbon atoms in (b) monolayer graphene sublattice and (c) bilayer graphene superlattice. g Representative transmission electron micrograph of graphene with overlapped square nanopore. The inset in (g) presents a magnified transmission electron micrograph of graphene. h Fitted extended X-ray absorption fine structure (EXAFS) spectra of Te foil and Te-doped graphene superlattice. i Density functional theory (DFT) calculation of the energy of diffusion for doped Te atoms towards either a pore edge or a framework. The inset in (i) depicts the atomic diffusion path of doped element on the graphene surface.