fig4

Figure 4. (A) XANES spectra and (B) FT-EXAFS spectra of Co SAs/NPs@N-CNTs, Co foil, CoO, Co₃O₄ and CoPc at Co K-edge; (C) FT-EXAFS fitting curve of Co SAs/NPs@N-CNTs in R space; Wavelet transform K³-weighted EXAFS plots of (D) Co foil, (E) CoPc and (F) Co SAs/NPs@N-CNTs. XANES: X-ray absorption near edge structure; FT-EXAFS: Fourier transform extended X-ray absorption fine structure; SAs: single atoms; NPs: nanoparticles; CNTs: carbon nanotubes.