Advanced single-atom Fe catalysts via sulfur-mediated spin engineering for high-performance Zn-air batteries

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are central to renewable energy technologies, yet their sluggish kinetics and reliance on scarce noble-metal catalysts hinder large-scale implementation. Here, we demonstrate that sulfur (S) -mediated spin-state engineering of single-atom Fe catalysts establishes a direct structure-spin-activity relationship for bifunctional oxygen electrocatalysis. Optimal S coordination shifts the Fe centers to a high-spin configuration within a porous hollow carbon architecture. This spin-state modulation optimizes the adsorption energetics of oxygen intermediates, lowering kinetic barriers for both ORR and OER. FeS 2 NC-h exhibits outstanding OER and ORR activity in alkaline media, achieving a low potential gap (ΔE) of 0.63 V, markedly outperforming the commercial Pt/C+IrO 2 (0.79 V). In rechargeable Zn-air batteries (RZABs), FeS 2 NC-h enables an open-circuit voltage of 1.50 V, peak power density of 202 mW cm −2 , specific capacity of 812 mAh g Zn −1 , and exceptional cycling durability exceeding 1200 h with round-trip efficiency >58%. This work establishes heteroatom-enabled spin-state engineering as a powerful strategy to transcend traditional coordination optimization, offering a general pathway to noble-metal-free integrated oxygen electrocatalysts for sustainable energy conversion and storage. Download: Download high-res image (302KB) Download: Download full-size image