Boosting oxygen reduction activity of Fe-N-C by partial copper substitution to iron in Al-air batteries

Iron and nitrogen co-doped carbon materials (Fe-N-C) have been widely investigated as one of the most promising electrocatalysts with low cost and excellent catalytic activity towards oxygen reduction reaction (ORR). Herein, inspired by the cytochrome c oxidase (CcO), we have proposed a high-performance bimetal Cu/Fe-regulating nitrogen-doped carbon (Cu-Fe-N-C) electrocatalyst via using partial copper substitution to iron in Fe-N-C. The optimized Cu-Fe-N-C composite displays much better catalytic activity than the pristine Fe-N-C indicated by 20 mV positive shift of onset potential (0.967 V vs RHE), 25 mV positive shift of half-wave potential (0.864 V vs RHE) and higher limiting-current density. The significantly enhanced performance is also manifested by a higher discharging cell voltage and better stability in practical Al-air batteries at a constant current density. Both experimental and computational results confirm that the significantly enhanced performance should be mainly ascribed to the synergistic effects of the bimetallic doping in Cu-Fe-N-C catalysts.