fig6

Figure 6. (A) The charge density difference of Fe-N-C/Pd_NC (top: top view; bottom: front view. The yellow and cyan regions represent electron accumulation and depletion, respectively). (B) Projected DOS diagrams of Fe-N-C and Fe-N-C/Pd_NC. (C) ORR polarization curves measured on RDE in O₂-saturated 0.1 M HClO₄ electrolyte for different catalysts. (D) Spin density diagrams of Fe-N-C and Fe-N-C/Pd_NC (the isosurface is 0.1 a.u.). (E) Tafel plots of catalysts. Reproduced with permission from Ref.^[94], © Elsevier Ltd. 2022. (F) Calculated relationship between μB and ΔE_ads (O₂) of FeN₃O and FeN₃O-O-Ti. (G) The PDOS of Fe 3d orbital for FeN₃O and FeN₃O-O-Ti and (H) The free energy changes for ORR. The blue dotted lines denote the d-band centers, while the gray dotted line denotes the Fermi level. Reproduced with permission from Ref.^[95], © WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 2022.