Engineering Electronic Spin State of a CoNi Alloy for an Efficient Oxygen Reduction Reaction

Developing cost-effective electrocatalysts for oxygen reduction reaction (ORR) is of great importance to improve the performance of metal–air batteries. Herein, a CoNi alloy encapsulated in an N-doped carbon framework (CoNi@NC) with a high saturation magnetization (89.1 emu g–1) is prepared by nanoalloying, and an external magnetic field is employed to directly enhance the ORR performance of CoNi@NC. The electronic structure of CoNi@NC is greatly optimized by electron cloud redistribution and spin-state adjustment, leading to Pt/C-comparable ORR performance in an alkaline electrolyte (the onset potential of 0.98 V and half-wave potential of 0.86 V in 0.1 M KOH). Furthermore, the CoNi@NC-based Al–air battery with magnet delivers a larger power density of 161.27 mW cm–2 and exhibits better durability compared with those with Pt/C. This work provides a promising approach to using magnetic induction to enhance oxygen reduction activity for metal–air batteries.