Electronic Bridges-Stabilized Fe–Cu Twin-Sites Circumvent Scaling Relationship for Robust Acidic Oxygen Reduction
Shiyu Li, Huang Ji, Yan Jin, Shuang Li, Meihuan Liu, Hao Tan, Haiqing Zhou, Hui Su
Abstract
The acidic oxygen reduction reaction (ORR) as the soul process in proton-exchange membrane fuel cells, faces fundamental limitations due to linear scaling relations (LSR) among adsorption energies at active sites. This intrinsic constraint typically leads to trade-offs between activity enhancement and compromised selectivity/stability. Here, the second-shell coordination engineering was proposed to construct the heteronuclear twin-site FeCu (TW-FeCu) catalyst, that can directly cleave the O–O bond without formation of sluggish *OOH species to disrupt the LSR of intermediate adsorption and minimize the activation energy for O–O bond scission. This well-designed Tw-FeCu catalyst demonstrates superior activity with a half-slope potential ( E 1/2 ) of 0.841 V and 4e – selectivity nearly 100% in acidic media, demonstrating promising potential as the energy device of H 2 /O 2 fuel cells (515 mW cm –2 ). A series of characterizations revealed that second-shell Cu coordination enhances Fe charge distribution via an electronic bridge channel, thereby suppressing metal leaching, while simultaneously enabling a twin-site cooperative coupling pathway to accelerate reaction kinetics. This work establishes a rational design strategy for highly efficient atomically dispersed ORR catalysts that circumvent LSR limitations.