Fig. 2
From: Regulating the coordination structure of single-atom Fe-NxCy catalytic sites for benzene oxidation
Structure characterization of Fe-NxCy SAs/N-C. a–c AC-HAADF-STEM images of the as-synthesized a Fe-N4 SAs/N-C, b Fe-N3C1 SAs/N-C, c Fe-N2C2 SAs/N-C. The insets are the corresponding structure model. The yellow, red and green balls refer to C, N, and Fe atoms, respectively. Scale bar, 5 nm. d HAADF-STEM-EDS mapping of the Fe-N4 SAs/N-C. Scale bar, 500 nm. e–g XANES spectra at the e C K-edge, f N K-edge, and g Fe L-edge. h XANES spectra at the Fe K-edge of the Fe-N4 SAs/N-C, Fe-N3C1 SAs/N-C, Fe-N2C2 SAs/N-C, Fe foil, Fe2O3, FeO. i FT k3-weighted χ(k)-function of the EXAFS spectra of the Fe-N4 SAs/N-C, Fe-N3C1 SAs/N-C, Fe-N2C2 SAs/N-C, and Fe foil. j WT of the Fe K-edge. k–m Comparison between the experimental K-edge XANES spectra and the theoretical spectra of k Fe-N4 SAs/N-C, l Fe-N3C1 SAs/N-C, m Fe-N2C2 SAs/N-C. The grayish-white, blue and pink balls refer to C, N, and Fe atoms, respectively
