fig9

Figure 9. (A) Top view of a single K atom absorbed in quaternary-N (N-Q), pyrrolic-N (N-5), and pyridinic-N (N-6). (B) The adsorption energy of different amounts of one N-6, two N-6, and three N-6. (C) The DOS of the defect site without N-doping, one, two, and three N-6 doping sites. (D) The barrier energy of one N-6, two N-6, and three N-6 doping sites. Copyright 2021, Electrochimica Acta[75].