Secondary-Atom-Assisted Synthesis of Single Iron Atoms Anchored on N-Doped Carbon Nanowires for Oxygen Reduction Reaction

The development of efficient Fe-N-C materials enriched with single-atom Fe sites toward the oxygen reduction reaction (ORR) is still a great challenge because Fe atoms are mobile and easily aggregate into nanoparticles during the high-temperature treatment. Herein, we proposed a facile and universal secondary-atom-assisted strategy to prepare atomic iron sites with high density hosted on porous nitrogen-doped carbon nanowires (Fe-NCNWs). The Fe-NCNWs showed an impressive half-wave potential (E-1/2) of 0.91 V and average kinetic current density (J(K)) of 6.0 mA cm(-2) at 0.9 V in alkaline media. They also held a high ORR activity in acidic solution with the E-1/2 of 0.82 V and average J(K) of 8.0 mA cm(-2) at 0.8 V. Density functional theory calculations demonstrated that the high ORR activity achieved is originated from single-atom iron sites that decrease the energy barrier in the reaction path efficiently.