Nitrogen-Doped Carbon Supported FeS Nanoparticles as a Bifunctional Electrocatalyst for High-Performance Zn–Air Batteries

The modification of TMS nanocrystals on highly conductive carriers (e.g., carbon black, graphene, carbon nanotubes) is an effective strategy to adjust the electronic structure and enhance the exposure of active sites, thereby achieving high-performance bifunctional electrocatalysts. In this study, a simple one-step pyrolysis strategy was employed to anchor FeS particles on a nitrogen-doped carbon electrocatalyst (FeS/NC). It was demonstrated that the use of NC as a carrier enriched the morphological structure, enhanced the specific surface area and graphitization degree, and thereby provided more active sites. More importantly, the strong electronic interaction between FeS and NC is suggested to optimize the free energy between reaction intermediates and adsorption sites, as well as the d-band center of FeS/NC, leading to a 0.19 V higher onset potential than that of pristine FeS. FeS/NC exhibited outstanding bifunctional oxygen catalytic performance for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) (ΔE = 0.87 V), superior to that of FeS and NC. Furthermore, rechargeable zinc-air batteries based on FeS/NC demonstrated a high peak power density (144.08 mW·cm–2), high specific capacity (716.74 mAh·gZn–1), high energy density (724.62 Wh·kgZn–1), and excellent stability.