Schiff-base polymer derived FeCo-N-doped porous carbon flowers as bifunctional oxygen electrocatalyst for long-life rechargeable zinc-air batteries

Rational design and exploration of low-cost and robust bifunctional oxygen electrocatalysts are vitally important for developing high-performance zinc-air batteries (ZABs). Herein, we reported a facile yet cost-efficient approach to construct a bifunctional oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) electrocatalyst composed of N-doped porous carbon nanosheet flowers decorated with FeCo nanoparticles (FeCo/N-CF). Rational design of this catalyst is achieved by designing Schiff-base polymer with unique molecular structure via hydrogen bonding of cyanuramide and terephthalaldehyde polycondensate in the presence of metal cations. It exhibits excellent activity and stability for electrocatalysis of ORR/OER, enabling ZAB with a high peak power density of 172 mW cm−2 and a large specific capacity of 811 mA h g−1Zn at large current. The rechargeable ZAB demonstrates excellent durability for 1000 h with slight voltage decay, far outperforming a couple of precious Pt/Ir-based catalysts. Density functional theory (DFT) calculations reveal that high activity of bimetallic FeCo stems from enhanced O2 and OH− adsorption and accelerated O2 dissociation by OO bond activation.