fig7

Figure 7. (A) Schematic illustration of the preparation of the nitrogen-doped CoSe/C composites. Copyright 2017, ACS Applied Materials and Interfaces^[50]. (B) The DFT optimized structure of N6, N6-N5-1, and N6-N5-NG-1 N-doped graphene and the corresponding electron density. The blue and red regions correspond to the electron-rich and electron-deficient regions, respectively. (C) Optimized top and side views of Na⁺ adsorption on corresponding structures. Copyright 2019, Applied Surface Science^[51]. Top views of the K-absorption models (D) of defect C, P-3, P-2, pyrrolic N, graphite N, and pyridinic N frameworks, the Ead, and the differential charge density distribution maps. (E-G) The TDOS and the PDOS before and after K adsorption. Copyright 2021, Applied Surface Science^[52].