High efficient oxygen reduction performance of Fe/Fe₃C nanoparticles in situ encapsulated in nitrogen-doped carbon via a novel microwave-assisted carbon bath method

Fe-based carbon materials are widely considered promising to replace Pt/C as next-generation electrocatalysts towards oxygen reduction reaction (ORR). However, the preparation of Fe-based carbon materials is still carried out by conventional heating method (CHM). Herein, a novel microwave-assisted carbon bath method (MW-CBM) was proposed, which only took 35 min to synthesize Fe/Fe₃C nanoparticles encapsulated in N-doped carbon layers derived from Prussian blue (PB). The catalyst contained large specific surface area and mesoporous structure, abundant Fe-N_x and CN active sites, unique core-shell structure. Due to the synergistic effects of these features, the as-prepared Fe/Fe₃C@NC-2 displayed outstanding ORR activity with onset potential of 0.98 V_RHE and half-wave potential of 0.87 V_RHE, which were more positive than 20 wt.% Pt/C (0.93 V_RHE and 0.82 V_RHE). Besides, Fe/Fe₃C@NC-2 gave a better stability and methanol tolerance than Pt/C towards ORR in alkaline media, too.