Enhanced Bifunctional Oxygen Electrocatalysis by Synergistic Active Heterostructure Design

Abstract Due to the slower kinetics and different reaction requirements of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), it is challenging to balance between the two reaction properties. In this work, CoFe 2 O 4 /Co heterostructure are designed by in situ loading of carbon dots (CDs) ‐mediated metal sites onto porous carbon sphere substrates (CSs) to achieve highly durable bifunctional catalysts (FeCoCDs/CSs). Experimental and theoretical calculations demonstrate that the strong metalcarrier interaction interface promotes dynamic electron transfer between CoFe 2 O 4 and Co, improves electronic conductivity, and enhances the stability of FeCoCDs/CSs catalysts. CDs effectively regulate the electronic environment of the active sites of Co, optimize the adsorption behavior of O * /OH * , and promote the release of final products. The designed FeCoCDs/CSs exhibit excellent ORR/OER performance with an oxygen potential difference (ΔE) of 0.635 V. Liquid zinc‐air batteries (ZABs) with FeCoCDs/CSs show outstanding cycling stability (Δ E ) of 0.635 V) and high round‐trip efficiency (64.7%). The flexible ZABs (FZABs) with FeCoCDs/CS also deliver excellent cycling stability over a wide temperature range (60–‐40 °C), demonstrating its ruggedness and suitability for practical applications under various environmental conditions.