Fig. 1: Support geometry engineering strategy and characterisation of the morphology, chemical, and electronic structures of ssCuNC and CuNC.

Schematic of the synthesis of (a) CuNC and (b) ssCuNC via support engineering. DCD dicyandiamide, PNP–Cu Cu-chelated polydopamine nanoparticles, ss–PNF–Cu Cu-bound polydopamine nanoparticles and films coated on ss. HAADF-STEM images with EDS mapping of C (yellow), N (blue), Cu (cyan) and O (tan) for c CuNC100 and d ssCuNC100. e N 1s and f Cu 2p XPS core spectra of ssCuNC100 and CuNC100. k3-weighted R-space Cu K-edge EXAFS spectra of (g) CuNC and (h) ssCuNC. i Cu K-edge EXAFS fitting in R space of CuNC100 and ssCuNC100. Simulated (Fit, yellow) curves are superimposed on experimental (Exp., blue) dots. Each spectrum contains the k3-weighted magnitude (dots) and real part (stars) of χ(R). j Average Cu–N bond lengths of CuN4 sites in CuNC and ssCuNC. Error bars represent one standard deviation from three independent trials. Source data are provided as a Source data file.