Mn–Fe dual atomic pairs on highly graphitized N-doped carbon support for oxygen reduction reaction

Abstract

Developing highly active and durable catalysts for the sluggish oxygen reduction reaction (ORR) is crucial for the widespread application of metal–air batteries. In this work, a Mn–Fe diatomic catalyst supported on N-doped carbon (Mn–Fe/NC) was synthesized via a two-step pyrolysis method. Structural characterization confirmed that the atomically dispersed Mn–Fe pair sites were anchored on a support rich in pyridinic N and graphitic N. The catalyst exhibits outstanding ORR performance in alkaline conditions, with a high half-wave potential of 0.903 V (vs. RHE), a low Tafel slope of 79.7 mV dec−1, and excellent stability (<10% decay after 15 h), outperforming commercial Pt/C and the corresponding single-metal counterparts. The enhanced activity is attributed to the synergistic electronic interaction between adjacent Mn and Fe sites. When applied as a cathode in zinc–air batteries (ZABs), Mn–Fe/NC delivers higher peak power density (80.3 mW cm−2) and specific capacity (806.1 mAh gZn−1) than Pt/C, demonstrating great potential for practical application in energy conversion devices.