Cobalt-nanoparticle impregnated nitrogen-doped porous carbon derived from Schiff-base polymer as excellent bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

Designing transition metal and nitrogen co-doped carbon as efficient oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) bifunctional electrocatalysts is pivotal for rechargeable zinc-air batteries. Herein, a triazine-containing poly(Schiff-base) has been synthesized and used as the nitrogen-rich precursor to prepare Co/Co 2 N modified nitrogen-doped porous carbon (Co@NC). The formed cobalt nanoparticles are impregnated in the porous carbon matrix with an intermediary layer of catalytically active Co 2 N. Co@NC exhibits a specific surface area of 2513 m 2  g −1 and remarkable bifunctional catalytic activities with a low gap of 0.76 V between ORR and OER overpotentials. The Co@NC-based battery possesses a peak power density of 141.6 mW cm −2 , a specific capacity of 776 mAh g −1 and superior long-term cycling stability, stemmed from the unique impregnated structure with sufficient accessible active sites.