Tailoring the Stability of Fe-N-C Via Pyridinic Nitrogen for Acid Oxygen Reduction Reaction

Developing advanced non-precious metal catalysts towards acidic oxygen reduction reaction (ORR) is critical for electrochemical energy conversion devices. Fe-N-C catalysts are demonstrated to be the most promising alternatives to platinum-based catalysts for ORR. Herein, Fe single atoms (SAs) coordinated by pyridinic nitrogen catalysts (denoted as Fe-pyridinic N-C) are synthesized through pyrolysis of ZIF-8 encapsulating ferrocene. Owing to the synergistic effects between Fe SAs and pyridinic N, Fe-pyridinic N-C exhibits remarkable ORR activity and outstanding stability in acid media, evidenced by golden kinetic current density of 9.71 mA cm -2 at 0.8 V, along with only 21 mV decrease in half-wave potential after 20000 cycles. Theoretical calculations demonstrate that pyridine-type N possesses stronger binding energy with Fe SAs compared with pyrrole-type N, thus, effectively stabilizing Fe SAs against demetallation. This study will be of great significance for the development of non-noble metal catalysts towards ORR with enhanced stability in acidic media.