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

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 Fe2O(SeO3)2/Fe3C@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 Fe2O(SeO3)2 crystal phase of Fe2O(SeO3)2/Fe3C@NC, and the Fe−O−Se bonds could obviously enhance ORR and OER catalytic performance of Fe2O(SeO3)2/Fe3C@NC. Density functional theoretical calculations (DFT) confirmed that the Fe2O(SeO3)2 in Fe2O(SeO3)2/Fe3C@NC had a higher d‐band center of Fe atom and a lower p‐orbital coupling degree with its own lattice O atom than Fe2O3, which leads to Fe site of Fe2O(SeO3)2 being more likely to adsorb external oxygen intermediates. The Fe−O−Se bonds in Fe2O(SeO3)2 results in the modification of coordination environment of Fe atoms and optimizes the adsorption energy of Fe site for oxygen intermediates. Compared with Fe2O3/Fe3C@NC, the Fe2O(SeO3)2/Fe3C@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 Fe2O(SeO3)2/Fe3C@NC‐based ZABs are higher than those of Pt/C+RuO2‐ZABs. The above results demonstrate that the asymmetrical Fe−O−Se bonds in Fe2O(SeO3)2 plays a key role in improving the bifunctional catalytic activities of ORR/OER for ZABs. The N‐doped carbon‐coated Fe‐based selenium oxide catalyst Fe2O(SeO3)2/Fe3C@NC was fabricated for zinc‐air batteries (ZABs). The Fe−O−Se bonds in Fe2O(SeO3)2/Fe3C@NC@NC could obviously enhance catalytic performance of ORR and OER because it can modify coordination environment surrounding Fe atoms and accordingly realize an optimization of the adsorption energy of oxygen intermediates. Furthermore, the Fe2O(SeO3)2/Fe3C@NC‐based ZABs exhibit superior peak power density and specific capacity in comparison to Pt/C+RuO2‐based ZABs.