Cu Nanoclusters Accelerate the Rate‐Determining Step of Oxygen Reduction on Fe─N─C in All pH Range.

Incorporating atom‐nanocluster interactions into Fe─N─C single‐atom catalysts (Fe‐SACs) represents a viable strategy for enhancing their oxygen reduction reaction (ORR) activity, however, further investigation is necessary to elucidate the underlying mechanism. Herein, Cu nanoclusters are incorporated into Fe‐SACs to realize markedly enhanced pH‐universal ORR performance and investigate the underlying mechanism. The rate‐determining step (RDS) investigation reveals that the existence of Cu nanoclusters does not alter the RDS of Fe─N─C despite their differences in acidic, neutral, or alkaline media but instead optimizes the electronic configuration of Fe─N─C and significantly promotes the RDS. The synergistic effect between the Fe single atoms and Cu nanoclusters significantly enhances the half‐wave potential by 45, 90, and 18 mV in the HClO4, PBS, and KOH electrolytes, respectively. The catalysts further demonstrate remarkable maximum power densities of 971.4, 94.9, and 234.7 mW cm−2 in H2/O2 fuel cells, neutral Zn‐air batteries, and alkaline Zn‐air batteries, respectively. [ABSTRACT FROM AUTHOR]