Fig. 2: Electronic and fine structural characterizations.

a Cu LMM spectra of Cuδ+NCN, CuNCN and CuO. b Normalized Cu K-edge XANES spectra and c the derived normalized χμ(E) spectra of Cuδ+NCN, CuNCN, CuO, Cu foil and standard Cu2O samples. d FT-EXAFS spectra of Cuδ+NCN, CuNCN, CuO, Cu foil and standard Cu2O samples. e Surface potential profiles of Cuδ+NCN, CuNCN and CuO. f FT-IR spectra of Cuδ+NCN, CuNCN and CuO.