“…In addition, a pair of peaks at binding energies of 712.05 eV (2p 3/2 ) and 725.65 eV (2p 1/2 ) can be assigned to Fe 2+ , which have a typical energy difference of 13.6 eV. As exhibited in Figure e, the N 1s spectra are deconvoluted into four peaks located at 398.3, 399.0, 399.9, and 400.9 eV, which could be ascribed to pyridinic N, N–Fe bond, pyrrolic N, and graphitic N, respectively. , However, compared with Fe 4 N-DMAC, the peak of graphite N in Fe 4 N-NMP is obviously enhanced, which may affect OER catalysis. Although the metal–N bond is proposed to easily form electron deficiencies that can absorb more OH – as active species, the formation of pyridinic N and graphitic N is also significant for accelerating the water-splitting process .…”