fig5

Figure 5. (A) Schematic diagram of d-orbital spin-electron filling states; (B) LSV curves of FeN/OC, FeNC and Pt/C 20% in 0.1 M KOH at the rotation speed of 1,600 rpm; (C) LSV curves of FeN/OC, FeNC and Pt/C 20% in 0.1 M HClO₄ at the rotation speed of 1,600 rpm; (D) Polarization curves and corresponding power density plots of FeN/OC, FeNC and Pt/C-assembled 2.0 bar H₂-O₂ PEMFCs^[55]. Copyright 2024, Wiley-VCH; (E) E_1/2, J_k, Tafel, mass activity, and TOF at 0.87 V of the catalysts in 0.1 M KOH and (F) 0.5 M H₂SO₄^[79]. Copyright 2024, Wiley-VCH; (G) In situ ATR-SEIRAS spectra of ORR over Co₁/BNG in O₂-saturated 0.1 M KOH^[80]. Copyright 2024, Wiley-VCH; (H) The corresponding EXAFS R-space fitting curves of CoSAs/PSNC^[81]. Copyright 2023, Wiley-VCH; (I) O₂ absorption energies on the optimized model structures of SnN₄ and SnN₂O^[83]. Copyright 2024, Wiley-VCH. LSV: Linear sweep voltammetry; PEMFCs: proton exchange membrane fuel cells; TOF: turnover frequency; ATR-SEIRAS: attenuated total reflection-surface-enhanced infrared absorption spectroscopy; ORR: oxygen reduction reaction; EXAFS: extended X-ray absorption fine structure.