FeN<sub>4</sub>S<sub>1</sub> Single-Atom Sites Anchored on Three-Dimensional Porous Carbon for Highly Efficient and Durable Oxygen Electrocatalysis
Shilong Zhou, Chao Chen, Jiawei Xia, Le Li, Xingyue Qian, Fengxiang Yin, Guangyu He, Qun Chen, Haiqun Chen
Abstract
Precisely designing asymmetric active centers and exploring their electronic regulation effects to prepare efficient bifunctional single-atom catalysts (SACs) is important for boosting the practical applications of zinc–air batteries (ZABs). Herein, an effective strategy has been developed by introducing an axial S atom to the FeN 4 active center, simultaneously assisted by pyrolyzing the graphene oxide (GO) sheathed zeolitic–imidazolate framework-8 (ZIF8) composite and constructing a three-dimensional (3D) porous framework with abundant FeN 4 S 1 moieties. This structure can accelerate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics owing to the modulated electronic redistribution and d -band center with a reduced energy barrier. The optimal S–Fe–NC/rGO showcases a lower voltage gap (Δ E ) of 0.64 V between both the ORR and OER half-wave potentials at 10 mA cm –2, highlighting the excellent bifunctional activities. The assembled S–Fe–NC/rGO rechargeable liquid ZABs deliver a power density of 154.05 mW·cm –2 and a desirable durability of >900 h. More importantly, the corresponding flexible solid-state ZABs exhibit considerable foldability.