Biomass gelatin-derived mesoporous nitrogen-doped carbon networks and its bifunctionality to effectively catalyze oxygen reduction and evolution reactions for rechargeable zinc-air battery

Developing cost-effective bifunctional catalysts with high performance to oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is key to the commercialization of rechargeable zinc-air batteries. Herein, biomass-derived gelatin is utilized as the common source of carbon and nitrogen to fabricate an iron and nitrogen co-doped carbon catalyst to ORR. Mesoporous carbon networks are generated by using silicon dioxide as the pore template in the preparation of the catalyst with a large BET surface area and hierarchical structure. Furthermore, nickel hydroxide particles are anchored on the carbon networks with high dispersion under the buffering of ammonia, which endows the carbon material with OER activity. The resultant catalyst FeGeSi-A2-Ni provides satisfactory bifunctionality to ORR and OER with 0.8693 V of ORR halfwave potential and 398 mV of OER overpotential at 5 mA cm⁻². Practically, the rechargeable zinc-air battery assembled from the FeGeSi-A2-Ni exhibits highly stable rechargeability with ∼ 1.15 V of discharge voltage and ∼ 2.05 V of charge voltage in the total process, being obviously excellent than the battery of Pt/C-RuO₂.