Electronic Structure of Nitrogen-Doped Graphene in the Ground and Core-Excited States from First-Principles Simulations
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- 作者：Xin Li ; Weijie Hua ; Jinghua Guo ; Yi Luo
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：July 23, 2015
- 年：2015
- 卷：119
- 期：29
- 页码：16660-16666
- 全文大小：524K
- ISSN：1932-7455
文摘
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 nitrogen-doping concentration have been analyzed in detail via both N 1s 鈫?蟺* and N 1s 鈫?蟽* transitions. The NEXAFS spectra are sensitive to the doping concentration of N in the 蟺* region: diluted doping weakens the main 蟺* peak and smears the oscillations in this region. The vacancy defect leads to a red-shift in both the 蟺 and 蟽 spectra. A pyridinic nitrogen at the 6V defect center exhibits a sharp 蟺* peak at 398.4 eV, which agrees well with the experimental pre-edge structure at 398.6 eV. The 蟽* 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.