Figure 3. Combined approach of three techniques for validation of surface structure and identification of Ag valence state.

(a) DFT-optimized model of the {110} NC surface showing the four different Ag sites shown in different colours. (b) Site-specific XANES spectra of the {110} surface were simulated by the FEFF program and then averaged. The simulated XANES spectra for the other surfaces are shown in the Supplementary Figs 10–13. (c) Averaged simulated XANES spectra were compared with experimental XANES spectra to verify the DFT models, as well as compared with reference materials to determine the valence state of Ag on the NC surfaces.