N,S co-doped porous carbon with Co9S8 prepared with a Co-FF-derived Co3O4 template: a bi-functional electrocatalyst for rechargeable zinc–air batteries

Abstract

To achieve broad commercialization of rechargeable metal–air batteries, the development of non-precious metal-based bi-functional oxygen electrocatalysts is critical. In this study, we prepared N,S co-doped porous carbon materials containing Co₉S₈ nanoparticles (Co₉S₈/NSC) through a one-step pyrolysis process. The process involved the pyrolysis of a polydopamine (PDA) coated Co-formic acid framework (Co-FF) derived Co₃O₄ and thiourea. The improved catalyst Co₉S₈/NSC-1 exhibited satisfactory long-term durability and superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity, the half-wave potential (E_1/2) of the ORR reached 0.83 V, and the OER overpotential at 10 mA cm⁻² (η₁₀) was 300 mV. The zinc–air battery (ZAB) based on Co₉S₈/NSC-1 assembly had a maximum power density of 102.0 mW cm⁻² and the cycle life reached 500 cycles. The material preparation method was simple, environmentally friendly and inexpensive, providing a feasible strategy for the development of non-precious metal-based electrocatalysts.