Structural characterization of the NCAC-Zn/Fe carbon aerogel. (a) N2 adsorption-desorption isotherm of NCAC-Zn/Fe. Inset is the corresponding pore size distribution. (b) Raman spectra of CAC, CAC/Fe, NCAC/Fe, and NCAC-Zn/Fe. (c) XPS spectra of the N 1s electrons in CAC/Fe and NCAC-Zn/Fe. (d) K-edge XANES of NCAC-Zn/Fe, FePc, and Fe foil. (e) K-edge EXAFS of NCAC-Zn/Fe, FePc, and Fe foil. (f) The corresponding EXAFS fitting curves for the NCALR/Fe sample.