Electronic Structure of Nitrogen-Doped Graphene in the Ground and Core-Excited States from First-Principles Simulations

Abstract

We have calculated the N 1s near-edge X-ray absorption fine structure (NEXAFS) spectra of nitrogen-doped monolayer graphene (NG) using density functional theory (DFT) with the equivalent core hole approximation. The hexavacancy (6V) defect and its dependence on the nitrogendoping concentration have been analyzed in detail via both N 1s → π* and N 1s → σ* transitions. The NEXAFS spectra are sensitive to the doping concentration of N in the π* region: diluted doping weakens the main π* peak and smears the oscillations in this region. The vacancy defect leads to a redshift in both the π and σ spectra. A pyridinic nitrogen at the 6V defect center exhibits a sharp π* peak at 398.4 eV, which agrees well with the experimental pre-edge structure at 398.6 eV. The σ* peak is split in two, which can serve as the fingerprint to reveal the nature of the defect. A structural change from pyridinic to pyrrolic NG results in a distinctive difference in the spectral shape. The ground-state band structure has also been simulated at the DFT level with periodic boundary conditions. Similar profiles are found in the N 2p projected density of states above the Fermi level and in the N 1s NEXAFS spectra.

N-Graphene Nanowalls via Plasma Nitrogen Incorporation and Substitution: The Experimental Evidence

“…To date, different groups confirmed theoretically that the formation of additional peaks in the “fingerprint” region (binding energy ~ 286–290 eV) of the graphene NEXAFS spectrum is mainly due to the structural defects [ 49 , 50 ]. Significant variations in the NEXAFS “fingerprint” region due to the interaction of heterogeneous atoms with the structural defects are also reported elsewhere [ 51 , 52 ]. Thus, comparing various established DFT calculations of the NEXAFS spectra with experimental results can enlighten the mechanism of interaction of nitrogen with the structural defects to form N-CNWs.…”

Nitrogen-doped graphene: Synthesis, characterizations and energy applications

“…A feature about 402 eV (N4) is observed, and it can be attributed to the attachment of urea species [33] . What is more, amino induced small features at about 399 eV (N1 and N2) can also be observed [92] . Because of a reduction of urea specie, decreased N4 peak is observed while the temperature increasing to 300 °C.…”

In Situ X-ray Photoelectron Spectroscopy Study of Lithium Interaction with Graphene and Nitrogen-Doped Graphene Films Produced by Chemical Vapor Deposition

“…Both spectra have two main resonances at 285.4 and 291.7 eV assigned to 1s → π* and 1s → σ* transitions, respectively (Figure b). Incorporation of N atoms in graphene results in a lowering of the π*-resonance intensity, due to the moving of a part of the carbon π-electron density toward nitrogen − and smearing of the σ*-resonance with an addition of imperfections in the lattice . The peaks at 287.1 and 288.6 eV are attributed to the transitions with participations of covalently functionalized carbon atoms …”