Atomic-scale characterization of nitrogen-doped graphite: Effects of dopant nitrogen on the local electronic structure of the surrounding carbon atoms

We report the local atomic and electronic structure of a nitrogen-doped\ngraphite surface by scanning tunnelling microscopy, scanning tunnelling\nspectroscopy, X-ray photoelectron spectroscopy, and first-principles\ncalculations. The nitrogen-doped graphite was prepared by nitrogen ion\nbombardment followed by thermal annealing. Two types of nitrogen species were\nidentified at the atomic level: pyridinic-N (N bonded to two C nearest\nneighbours) and graphitic-N (N bonded to three C nearest neighbours). Distinct\nelectronic states of localized {\\pi} states were found to appear in the\noccupied and unoccupied regions near the Fermi level at the carbon atoms around\npyridinic-N and graphitic-N species, respectively. The origin of these states\nis discussed based on the experimental results and theoretical simulations.\n