Synthesis of self-supported non-precious metal catalysts for oxygen reduction reaction with preserved nanostructures from the polyaniline nanofiber precursor

► Novel preparation of self-supported and nano-structured NPMCs for ORR. ► An onset potential of 0.905 V vs. RHE and nearly four-electron ORR pathway. ► Effects of ferrous species in precursors on the final catalysts explored. ► Onset ORR potentials increasing with the initial Fe content from 0 to 3.0 wt.%.