Nanoporous graphene homojunction mediated by interface charge transfer

The construction of carbon-based hetero- or homojunctions is a key strategy for expanding their functional boundaries and enabling new quantum devices. On-surface synthesis provides a promising route for the precise fabrication of such structures. Although significant progress has been achieved in one-dimensional graphene nanoribbon hetero- or homojunctions, analogous two-dimensional systems remain largely unexplored. Here, we developed an AgTe monolayer intercalation method to fabricate nanoporous graphene (NPG) homojunctions. By controlling tellurium deposition, NPG islands spanning both the Ag(111) substrate and the AgTe monolayer were successfully synthesized. Owing to the interfacial charge transfer differences, the NPG exhibits different semiconductor behaviors on Ag(111) and the AgTe monolayer, resulting in the formation of an NPG homojunction with the type-II band alignment. The entire fabrication process of the NPG homojunctions was examined by scanning tunneling microscopy, and evidence for the type-II band alignment was obtained by scanning tunneling spectroscopy and density functional theory calculations. This intercalation strategy circumvents the randomness inherent in the synthesis of carbon-based heterostructures and offers a promising route toward two-dimensional carbon-based junctions with controllable band alignment.