fig5

Figure 5. The catalytic mechanism of Fe₂NC. (A-D) On Fe₁NC and Fe₂NC nanozymes, (A) the structure diagram for adsorbed oxygen; (B) the charge density (yellow isosurfaces: the increase of 0.02 e/Å^-3 for electronic density; blue isosurfaces: the decrease of 0.02 e/Å^-3 for electronic density); (C) PDOS of the oxygen adsorption state, with the dashed line indicating the Fermi level and the solid lines representing the d-band centers of Fe and the p-band centers of O for each sample. (D) The free energy diagram for oxygen reduction pathways via AEM and ODM. (E) the diagram illustration of O₂ reduction process, with AEM shown on the left and ODM on the right. Reproduced with permission from Ref.^[53] Copyright 2021, Springer Nature.