The Heterointerface between Fe₁/NC and Selenides Boosts Reversible Oxygen Electrocatalysis

The rational design and construction of efficient and inexpensive bifunctional oxygen electrocatalysts are highly desirable for the development of rechargeable Zn-air batteries (ZABs). Although single-atom Fe sites anchored on N-doped carbon catalysts (Fe-1/NC) ensure high oxygen reduction reaction activity, their unitary atomically dispersed active center faces difficult condition in catalyzing oxygen evolution reaction simultaneously. Herein, a composite catalyst containing heterointerface between Fe-1/NC and selenides ((Fe,Co)Se-2) is constructed. The obtained (Fe,Co)Se-2@Fe-1/NC exhibits extremely narrow potential gap of 0.616 V and remarkable stability in alkaline media, outperforming the benchmark catalysts (Pt/C+RuO2: 0.720 V). Experimental results and density functional theory calculations reveal that heterointerface between Fe-1/NC and (Fe,Co)Se-2 accelerates the electron transfer and provides more moderate adsorption sites, which endow (Fe,Co)Se-2@Fe-1/NC with extremely high bifunctional oxygen catalytic activity. This study not only provides a superior bifunctional catalyst for ZABs, but also enriches the application of single-atom catalysts in multifunctional energy storage and conversion devices.