Fig. 5From: Ultrasonic Plasma Engineering Toward Facile Synthesis of Single-Atom M-N4/N-Doped Carbon (M = Fe, Co) as Superior Oxygen Electrocatalyst in Rechargeable Zinc–Air BatteriesThe local electronic state and chemical environment of Fe-N4/NC. a Comparison of Fe K-edge XANES spectra of Fe foil, Fe2O3, FePc, and Fe-N4/NC. b Fourier transform of the EXAFS spectra of Fe foil, Fe2O3, FePc, and Fe-N4/NC. c, d EXAFS analysis of Fe-N4/NC at K and R space, respectively. The inset in d demonstrates the model derived from the EXAFS results. e Wavelet transform of Fe K-edge XANES spectra of Fe foil, Fe2O3, FePc, and Fe-N4/NCBack to article page