Fig. 1: Structure analysis of Fe–NC and Fe–NCBrCl catalysts.

a Aberration-corrected atomic resolution HAADF-STEM micrograph of Fe–NCBrCl. b, c HAADF-STEM images and corresponding EDS mapping. d XAS spectra collected at N K-edge. e The deconvoluted high-resolution N 1s XPS. f The hysteresis curves. g Normalized Fe K-edge XANES spectra. h Fourier transform of k3-weighted EXAFS spectra. i FT-EXAFS fitting curve, gray ball represents C atom, blue ball represents N atom, red ball represents Fe atom, yellow ball represents Br atom.