Fig. 2: Structural characterizations of various catalysts.

a XPS spectra of Cu–N₄ SAC, Cu–N₃ SAC, and Cu NPs/C₃N₄. b CO-DRIFT spectra of Cu–N₄ and Cu–N₃ SACs. c XANES and (d) EXAFS spectra of Cu–N₄ SAC, Cu–N₃ SAC, Cu foil, Cu₂O, and CuO at Cu K-edge. e Wavelet transform of EXAFS spectra at Cu K-edge. Source data are provided as a Source Data file.