Doubly-enhanced strategy to construct a highly efficient carbon-based bifunctional catalyst to oxygen reduction and oxygen evolution reactions for rechargeable zinc-air batteries

Regulating the oxygen evolution reaction (OER) performance of N-doped carbon-based catalyst to oxygen reduction reaction (ORR) is of prospective to the wide-ranging applications of rechargeable zinc-air batteries. In this work, a facile double-enhancing strategy is proposed to prepare a bifunctional catalyst to ORR and OER. In the strategy, the smaller carbon particles were generated by carbonizing cyclodextrin. The fresh carbon particles can well react with the gasified product of melamine to facilitate the anchoring of nitrogen to prepare the N- doped Fe-N-CD-C-A2 catalyst for ORR. Then, an OER enhanced bifunctional catalyst Fe-N-CD-C-A2-Ni was prepared by separately blending Ni2+and OHwith Fe-N-CD-C-A2 to evenly load Ni(OH)2 particles as an OER catalyst. Benefiting from the intentionally regulated properties, the Fe-N-CD-C-A2-Ni shows 0.8728 V of ORR half wave potential and 1.5868 V of OER potential at 10 mA cm2, both being realized in a practical rechargeable zinc-air battery with 1.526 V of open circuit potential, 192 mW cm2 of peak power density, 1.18-1.27 V of discharge voltage plateau and 957 mWh g-1 Zn of energy density. Importantly, the Fe-N-CD-C-A2-Ni exhibits superior rechargeability and durability during the discharge-recharge cycles, being better than Pt/C +RuO2 catalyst and revealing promising prospects for practical application