Fig. 3: Determination of the GCN adsorption sites and the coordination of the Cu atoms.

a−c Cu 2p, C 1s, and N 1s regions of experimental XPS and their corresponding deconvolution. The inset in (a) shows the LMM Auger peak of Cu. For the attribution of the N 1s components in (c), see Table S2 and Fig. S3e. d Top view of the structure of one model included in the ‘high’ coverage regime of Cu-GCN: C, N, H, and Cu are represented by grey, blue, white, and orange spheres, respectively. The green, orange, red and blue circles indicate the inequivalent N atoms, namely pyridinic, primary amino, secondary amino, and graphitic, respectively. Additionally, the triangle, square, and rhombus indicate the ‘Amino I’, ‘Amino II’ and ‘Top’ adsorption sites for Cu. e Simulated N 1s XPS spectrum of the mixture of coverage regimes (dashed red line) compared with the experimental one for Cu-GCN(20) (dotted grey line); contributing spectra from different regimes are also shown; below, lines for different N atoms at each regime (for pristine, lines of alternated and linear models are resolved whereas for low and high coverage regimes there is no resolution for different models).