Structurally engineered bifunctional oxygen electrocatalysts derived from a cobalt-based LDH-MOF architecture

Abstract

A pivotal challenge for rechargeable zinc–air batteries (ZABs) lies in designing air electrocatalysts that enable simultaneous enhancement of oxygen reduction and evolution reaction (ORR/OER) kinetics because the inefficiency of either reaction directly limits both power-energy performance and cycling durability. Herein, we present a rationally designed bifunctional oxygen electrocatalyst derived from a self-assembled cobalt-based metal–organic framework-layered double hydroxide (Co-LDH-MOF) hybrid precursor, fabricated via a rapid and scalable ultrasonication-assisted aqueous route. The resulting material featured a compact core–shell architecture comprising curved, N-rich carbon layers for efficient ORR and abundant exposed CoO_x sites for enhanced OER, while the strongly coupled metal-carbon interface facilitated electron transfer and reinforced electrochemical durability. Correspondingly, the catalyst exhibited exceptional bifunctional activity, reflected in a small potential gap (ΔE = E_j10 – E_1/2) of 0.69 V, outperforming the ZIF-67-derived counterpart (0.85 V) and the noble-metal benchmark Pt/C–RuO₂ (0.75 V). When assembled into a ZAB, it maintained a narrow charge–discharge voltage gap with minimal decay over 1000 h of charge–discharge cycling, ranking among the top-performing Co-based bifunctional catalysts reported. This work validates precursor-guided structural engineering as an effective strategy for the construction of electrocatalysts with dense and synergistic active sites for advanced energy applications.