Breaking the Linear Scaling Relationship: Bioinspired Electronic Coupling in S-Bridged Fe-Fe Dual Sites for Efficient...

Dual-atom catalysts (DACs) provide a promising approach to overcome the linear scaling relationship that limits the activity of single-atom catalysts for oxygen reduction reactions (ORR). However, the lack of a direct electronic bridge between the two sites, along with the inherently localized character of transition-metal 3d orbitals, often hinders coherent electronic regulation and efficient orbital overlap with reaction intermediates. Herein, inspired by the natural iron-sulfur clusters, we design an S-bridged Fe-Fe DAC (Fe₂N₆-S/SNC). The sulfur bridge acts as an intrinsic charge-transfer channel, enabling strong electronic coupling between the Fe centers. Combined experimental and theoretical analyses demonstrate that this configuration promotes dynamic charge redistribution and enhances Fe 3d-S 2p orbital hybridization, which cooperatively optimizes oxygen intermediate adsorption and enhances the ORR kinetics. Consequently, Fe₂N₆-S/SNC exhibits outstanding alkaline ORR performance with a half-wave potential of 0.93 V, a kinetic current of 35.40 A g^-1, and a high turnover frequency of 2.49 e^- site^-1 s^-1. When integrated into an ampere-hour-scale zinc-air battery, it delivers a discharge capacity of 4.76 Ah and a peak power of 2.67 W. This work demonstrates a bio-inspired bridging strategy to create electronically coherent dual-atom sites, offering fresh perspectives on the rational design of high-performance DACs for energy conversion devices.