Fe-N4/Co-N4 active sites engineered porous carbon with encapsulated FeCo alloy as an efficient bifunctional catalyst for rechargeable zinc-air battery

Design and synthesis of earth-abundant elements-based electrocatalysts with sufficient activity and stability remain challenging for oxygen-involved electrochemical energy conversion and storage devices. In this work, catalyst with simultaneously engineered Fe-N 4 and Co-N 4 active sites and graphitic carbon multilayer-encapsulated FeCo alloy is developed by pyrolysis of metal salts doped G-g-C 3 N 4 . The obtained composite material exhibits promising catalytic activity and good stability for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte , as evidenced by the positive shift of half-wave potential by 44 mV compared to 20% Pt/C for ORR and the potential of 1.596 V at current density of 10 mAcm −2 for OER. In addition, the thus-assembled rechargeable zinc-air battery using the synthesized material as cathode delivers a maximum power density of 311.2 mWcm −2 with an open circuit potential of 1.51 V and a long-term cycling stability. DFT calculation results indicate that catalyst with composite active sites displays smaller energy barrier than that with single active site.