Construction of Fe/Co-N 4 Single-Atom Sites for the Oxygen Reduction Reaction in Zinc-Air Batteries.

Insight into the modulation effect of oxygen reduction reaction (ORR) active centers is of profound significance but remains a great challenge. Here, we designed Co, Fe dual-metal single-atom sites (CoFe-DSAs/NC) uniformly anchored on nitrogen-doped multiwalled carbon nanotubes for boosting ORR performance through regulating the 4d electronic orbitals of the Co-N 4 active site. Mechanism studies revealed that for the first time the neighboring Fe-N 4 atomic sites were able to regulate the d-band center of Co-N 4 single-atom active centers while maintaining the balance of adsorption-desorption affinity for O 2 and oxygen-containing species on Co-N 4 , thereby resulting in a superior ORR performance with a positive half-wave potential (0.90 V vs RHE). The assembled zinc-air battery based on CoFe-DSAs/NC exhibited an increased open-circuit voltage (1.48 V) and an elevated specific capacity (782.33 mAh·g -1 ). The work provides a new clue for reasonably designing high-performance ORR catalysts through adjusting the d-band center of active sites.