fig5

Figure 5. X-ray absorption spectroscopy of samples. (A) Co K-edge XANES spectra of Co foil, CoO, Co₃O₄, (Co)N, and (FeCoNiCuZn)N; (B) EXAFS fitting of (FeCoNiCuZn)N; (C) Fourier transform (FT) of the Co K-edge EXAFS spectra of Co foil, (Co)N, and (FeCoNiCuZn)N; (D) The corresponding EXAFS fitting curve of Co-(FeCoNiCuZn)N: Fe (yellow), Co (grey), Ni (green), Cu (pink), and Zn (blue); (E) the WT contour plot of Co foil, (Co)N, and (FeCoNiCuZn)N.