Structural characterization of nitrogen-doped y-graphynes by computational X-ray spectroscopy

Heterogeneous atomic doping, especially with nitrogens, can improve the interfacial properties and electrical conductivity of carbon-based materials like y-graphyne (y-GY), thereby improving the energy storage capacity and expanding various electrical applications. Properties of doped structures are affected by the local structures around the impurity atoms, which can be sensitively determined by the X-ray photoelectron (XPS) and near-edge X-ray absorption fine-structure (NEXAFS) spectra. In the present work, we have simulated the XPS and NEXAFS spectra of pristine y-GY as well as five nitrogen-doped y-GYs in both the C and N K-edges with the density functional theory. The theoretical C and N 1s ionic potentials of the N-doped systems can be well fitted to the experimentally XPS spectra, which can accurately characterize the experimental peaks. These five N-doped y-GYs can be well distinguished by NEXAFS. Our results provide clear local structure-spectroscopy relation and a theoretical reference for identifying different N-doped y-GYs, which are also insightful for general two-dimensional carbon-based materials.