fig4

Figure 4. In-situ XAS characterizations of FCNCuMO_X@CNT under variations of applied potentials. XANES spectra of K-edge of (A) Fe, (B) Co, (C) Ni, (D) Cu, and (E) Mo; Inset figure of panel (C) shows locally enlarged absorption spectra; FT-EXAFS spectra of K-edge of (F) Fe, (G) Co, (H) Ni, (I) Cu, and (J) Mo; (K) Locally enlarged spectra of panel (H); (L) Fitted first-shells of Ni at OCP and 0.65 V. CNTs: Carbon nanotubes; XAS: X-ray absorption spectroscopy; XANES: X-ray absorption near edge structure; FT-EXAFS: fourier-transformed extended X-ray absorption fine structure; OCP: open circuit potential.