Cobalt oxide nanosheets anchored on loofah sponge-derived carbon as a high-performance bifunctional electrocatalyst for rechargeable zinc-air batteries

Rechargeable zinc-air batteries need bifunctional electrocatalysts to improve the kinetics of both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Herein, we prepare a CoO@NC catalyst employing the 'carbonization-solvothermal-calcination' method, which involves affixing CoO nanosheets to the nitrogen-doped carbon matrix derived from the loofah sponge. The synergy of NC and CoO components creates abundant active sites, and their hierarchical porous structure enables the swift movement of relevant species, thus allowing the CoO@NC catalyst to display remarkable bifunctional performance with a potential difference of 0.73 V. Additionally, the CoO@NC-driven zinc-air battery exhibits a remarkable peak power density of 112.4 mW cm-2 and works reliably for more than 200 h, outperforming the commercial Pt/C-RuO2 catalysts. This research proposes a novel strategy for constructing noble-metal-free bifunctional electrocatalysts.