The Asymmetrical Fe−O−Se Bonds in Fe₂O(SeO₃)₂ Boosting Bifunctional Oxygen Electrocatalytic Performance for Zinc‐Air Battery

Abstract Zinc‐air batteries (ZABs) have the advantages of high energy density and rich zinc raw materials. It is a low‐cost, green and sustainable energy storage device. At present, one of the key technologies that hinder the large‐scale application of ZABs is the design and fabrication oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) bifunctional catalysts with excellent performance, especially the non‐platinum‐based catalysts. Here N‐doped carbon‐coated Fe‐based selenium oxide catalyst Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC with high performance has been fabricated by a one‐step pyrolysis and then the electrochemical oxidization. The experimental results confirmed that the existence of Fe−O−Se bonds in Fe 2 O(SeO 3 ) 2 crystal phase of Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC, and the Fe−O−Se bonds could obviously enhance ORR and OER catalytic performance of Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC. Density functional theoretical calculations (DFT) confirmed that the Fe 2 O(SeO 3 ) 2 in Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC had a higher d ‐band center of Fe atom and a lower p ‐orbital coupling degree with its own lattice O atom than Fe 2 O 3 , which leads to Fe site of Fe 2 O(SeO 3 ) 2 being more likely to adsorb external oxygen intermediates. The Fe−O−Se bonds in Fe 2 O(SeO 3 ) 2 results in the modification of coordination environment of Fe atoms and optimizes the adsorption energy of Fe site for oxygen intermediates. Compared with Fe 2 O 3 /Fe 3 C@NC, the Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC showed the obvious enhancements of ORR/OER catalytic activities with a half‐wave potential of 0.91 V for ORR in 0.1 M KOH electrolyte and a low overpotential of 345 mV for OER at 10 mA cm −2 in a 1.0 M KOH electrolyte. The peak power density and specific capacity of Fe 2 O(SeO 3 ) 2 /Fe 3 C@NC‐based ZABs are higher than those of Pt/C+RuO 2 ‐ZABs. The above results demonstrate that the asymmetrical Fe−O−Se bonds in Fe 2 O(SeO 3 ) 2 plays a key role in improving the bifunctional catalytic activities of ORR/OER for ZABs.