N 1s HXPES spectra. (a) FePc/PhRs and (b) HB-FePc catalysts, each spectrum fitted with Voigt functions followed by background subtraction by the Shirley method (dashed line). Orange, green, red, and purple solid lines are pyridine-like or FePc (NP1), pyrrole- or cyanide-like (NP2), graphite-like (NP3), and oxide (NP4) nitrogen components, respectively. (c) Structural formulae of four nitrogen components in graphite. (d) Plot of calculated nitrogen content as a function of pyrolysis temperature.