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

Abstract

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 (E1/2) of 0.91 V and average kinetic current density (JK) 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 E1/2 of 0.82 V and average JK 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.