Field Effect and Local Gating in Nitrogen‐Terminated Nanopores (NtNP) and Nanogaps (NtNG) in Graphene

Functionalization of electrodes is a wide‐used strategy in various applications ranging from single‐molecule sensing and protein sequencing, to ion trapping, to desalination. We demonstrate, employing non‐equilibrium Green′s function formalism combined with density functional theory, that single‐species (N, H, S, Cl, F) termination of graphene nanogap electrodes results in a strong in‐gap electrostatic field, induced by species‐dependent dipoles formed at the electrode ends. Consequently, the field increases or decreases electronic transport through a molecule (benzene) placed in the nanogap by shifting molecular levels by almost 2 eV in respect to the electrode Fermi level via a field effect akin to the one used for field‐effect transistors. We also observed the local gating in graphene nanopores terminated with different single‐species atoms. Nitrogen‐terminated nanogaps (NtNGs) and nanopores (NtNPs) show the strongest effect. The in‐gap potential can be transformed from a plateau‐like to a saddle‐like shape by tailoring NtNG and NtNP size and termination type. In particular, the saddle‐like potential is applicable in single‐ion trapping and desalination devices. Mind the gap termination! Graphene nanopore (nanogap) single‐species edge functionalization leads to a termination‐dipole‐induced in‐pore (in‐gap) electrostatic field. The termination‐dependent field increases or decreases electronic transport through a molecule in the nanogap by shifting its levels by almost 2 eV with respect to the electrode Fermi level. Such a field effect, akin to field‐effect transistors is applicable in single‐ion trapping and desalination devices.