Fig. 2: Structure characterizations.

a Normalized Cu K-edge XANES and (b) FT-EXAFS spectra of different Cu-Nx-y catalysts. c FT-EXAFS spectra and corresponding fitting EXAFS spectra of Cu foil and different Cu-Nx-y catalysts. d Wavelet transform EXAFS plots of different Cu-Nx-y catalysts. All the FT-EXAFS data are presented without phase correction. The grayish-white, light blue and dark blue refer to C, N, and Cu atoms, respectively.