Biphase Alloy Nanoheterojunction Encapsulated within N‐Doped Carbon Nanotubes as Bifunctional Oxygen Electrocatalyst for High‐Performance Zn‐Air and Mg‐Air Batteries

Abstract N‐doped carbon confined alloy catalysts possess considerable potential in facilitating oxygen electrocatalytic reaction and consequent applications in metal air batteries, but the sluggish catalytic kinetics and high reaction barrier of oxygen reduction reaction (ORR) remain the bottleneck restricting its further development. Here, a novel CoFe‐NiFe biphase alloy nanoheterojunction encapsulated within N‐doped carbon nanotubes (CoFe‐NiFe@NCNT) is fabricated via the hydrothermal carbothermic reduction approach. Owing to the plentiful active sites and high electrical conductance, the potential difference between OER and ORR amounts to merely 0.68 V. Simultaneously, the performance of the Zn‐air and Mg‐air batteries assembled by CoFe‐NiFe@NCNT serving as the air‐cathode are superior to that of commercial Pt/C + RuO ₂ . The DFT outcomes reveal that the transformation between *OOH and *O is the rate‐determining step (RDS) of ORR/OER. Also, the synergy between the biphase alloy heterojunction and N‐doped carbon nanotubes is conducive to reduce the reaction energy barrier. This study offers a profound understanding toward the structural design of biphase alloy nanoheterojunction electrocatalysts and the utilization in metal‐air batteries for portable wearable electronic apparatuses.