Fig. 3: Characterizations of Ni-based catalysts.

Nitrogen physisorption isotherm (a), and pore size distribution of NC, NC-T, and NiN2-Nin (n = 5, 6, 10) samples (b). c Small-angle X-ray Scattering (SAXS) of NC, NC-T, and NiN2-Nin (n = 5, 6, 10) samples. X-ray absorption of various Ni catalysts and standard materials, XANES (d) and EXAFS (e) spectra and fitting data for all related Ni materials. Source data for Fig. 3 are provided as a Source Data file.