Space-Confined Growth of Co₉S₈ Nanoparticles in Covalent Organic Framework-Derived Porous Carbon for Efficient Bifunctional Oxygen Electrocatalysis

Fine regulation of the physicochemical structure of carbon-based electrocatalysts to optimize the adsorption energies of oxygen intermediates is critically important to enhance the reaction kinetics of the oxygen evolution/reduction reaction (OER/ORR) but remains a huge challenge. Herein, nano-space confined growth of Co₉S₈ nanoparticles (NPs) in porous carbon is realized through an in situ confined growth strategy by using thiol-chains functionalized COF (COF-S-SH) as a confined template. COF-S-SH is used as binding sites to immobilize Co ions to improve the interaction between metal nanoparticles (NPs) and carbon skeletons, and simultaneously serves as a confined void to avoid the aggregation metal NPs. Impressively, as an efficient bifunctional catalyst, the resulting Co₉S₈/COF-S₈₀₀ shows significantly enhanced oxygen electrocatalysis with a small OER-ORR voltage gap of 0.76 V, vastly superior to that of pristine COF-S₈₀₀. Furthermore, the assembled Zn–air battery with Co₉S₈/COF-S₈₀₀ catalyst displays a high peak power density of 181.5 mW cm⁻² and great durability over 60 h charge–discharge cycles.