Hierarchically porous Fe/N/S/C nanospheres with high-content of Fe-Nx for enhanced ORR and Zn-air battery performance

Heteroatom-doped carbon-based transition-metal single-atom catalysts (SACs) are promising electrocatalysts for oxygen reduction reaction (ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N-S-doped carbon catalyst (FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential (E1/2) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm-2 for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites (up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres (NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2 charge-discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion. (c) 2022 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).