MOF-derived multi-metal embedded N-doped carbon sheets rich in CNTs as efficient bifunctional oxygen electrocatalysts for rechargeable ZABs

摘要

The rational design and preparation of bifunctional electrocatalysts with pleasant oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is crucial for extensive commercial applications of rechargeable Zn-air batteries (ZABs). Herein, we report a simple method to obtain multi-metal (Fe, Ni, Zn) embedded in N-doped carbon sheets entan-gled with carbon nanotubes (CNTs) as superior oxygen electrocatalysts (FeNi-NCS-2). The resultant FeNi-NCS-2 exhibits an impressive electrochemical performance, providing a reversible oxygen overpotential as low as 0.758 V. The ZAB with FeNi-NCS-2 as the air cathode shows a promising capacity of 639.71 mAh g(-1) at 20 mA cm(-2), a power density of 109.8 mW cm(-2) and cycling stability of over 130 cycles at 10 mA cm(-2) with an energy efficiency of about 55, superior to the ZAB based on Pt/C-IrO2. The satisfactory electrocatalytic per-formance is mainly due to the Fe, Ni-based nanoparticles protected by graphitic carbon layers, hierarchical porous lamellar structures that promote the accessibility between the active centers and the electrolyte as well as self-growing tangled carbon nanotubes that provide fast transmission channels. This study presents a facile way for the synthesis of highly efficient ORR/OER bifunctional electrocatalysts for high-performance rechargeable ZABs. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.