fig3

Figure 3. (A) Normalized Ni K-edge XANES spectra of NiO_x@DG and reference materials; (B) FT of Ni K-edge EXAFS data of NiO_x@DG and reference materials. The boxed area is enlarged in Figure 3A’s inset; (C) Ni K-edge WT-EXAFS contour plots for NiO_x@DG and reference materials; (D) Ni K-edge EXAFS fitting curves for NiO_x@DG. XANES: X-ray absorption near-edge structure; DG: defective graphene; FT: fourier transform; EXAFS: extended X-ray absorption fine structure; WT: wavelet transform.