Redox Activity of Co Species in the Active Sites of CoNx/CoOx Facilitates Oxygen Electrocatalysis for Zn‐Air Batteries

Abstract Developing efficient bifunctional oxygen electrocatalysts is crucial for enhancing the performance of rechargeable Zn‐air batteries (ZABs). In this study, cobalt/cobalt oxides embedded in N‐doped carbon nanofibers (Co/CoO x /NCNFs) were synthesized through a combination of electrospinning and annealing processes. The resulting Co/CoO x /NCNFs catalysts feature abundant CoN x and CoO x active species, leveraging the large specific surface area of nanofibers to facilitate oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The optimized Co/CoO x /NCNFs‐0.1 achieved a half‐wave potential (vs. RHE) of 0.82 V and required only 429 mV to reach 10 mA cm −2 in a typical three‐electrode system with 0.1 M KOH using an electrochemical workstation equipped with a pine instruments rotator, outperforming the Pt/C+RuO 2 . The assembled ZABs exhibited high specific capacity (771 mAh g Zn −1 ), substantial power density (981.6 mWh g Zn −1 ), and long‐term stability (>325 h). In situ Raman spectroscopy confirmed that the electrocatalytic processes involve the redox activity of Co (II and III) species derived from abundant CoN x and CoO x , elaborating the origin of the catalysts’ exceptional oxygen electrocatalysis performance. This work not only presents a straightforward and effective approach for producing bifunctional oxygen electrocatalysts in ZABs but also sheds light on the catalytic mechanisms underlying ORR and OER for CoN x /CoO x ‐based oxygen electrocatalysts.