▎ 摘　　要

Double atoms catalysts (DACs) emerged very recently as excellent materials and were used in various catalytic reactions due to their excellent catalytic activity. Although active research on the design DACs has been ongoing for almost a decade, little attention has been paid to the detailed catalytic mechanisms. Based on density functional theory (DFT) analysis, the iron dimer embedded in N-containing graphene (FeFe@N6) has the most excellent adsorption properties of O2 and CO among DACs systems (M1M2@N6, M1/M2 = Fe, Co, Ni). We considered the influence of N atoms concentration and position on the adsorption performance and stability of the iron dimer, FeFe@N6 was screened as a potential DAC. We systematically studied the catalytic mechanisms of CO oxidation on FeFe@N6 and its monometallic counterpart (VFe@N6). CO oxidation on FeFe@N6 along the Eley-Rideal (ER) and termolecular Eley-Rideal (TER) mechanisms needs to overcome the low energy barriers of 0.513 eV and 0.299 eV, which is smaller than the maximum energy barrier (0.584 eV) of CO oxidation along the Langmuir-Hinshelwood (LH) mechanism on VFe@N6. Therefore, FeFe@N6 has high activity for CO oxidation, which can provide useful guidance for the development of low-cost and efficient green DACs.