Direct single-atom/cluster interactions induce electron decoupling to promote the oxygen reduction reaction

Nitrogen-doped carbon-supported transition metal single atoms (TM-N-C) catalysts have demonstrated advanced oxygen reduction reaction (ORR) kinetics. However, the strong coupling of electrons between metal sites and the substrate results in suboptimal O 2 adsorption and activation behavior, which still needs to be addressed. In this work, we construct Fe-O-Fe electronic bridges between single atoms and clusters via an in situ cluster trimming strategy, effectively alleviating the electron confinement at single-atom sites and achieving optimized O 2 catalytic behavior. Specifically, in situ electrochemical experiments and theoretical analyses demonstrate that the optimized electron transfer capability not only provides thermodynamic advantages in the O 2 adsorption process and reduces adsorption resistance but also significantly activates the O O bonds, effectively breaking the trade-off between activity and stability. The target catalyst exhibited outstanding ORR catalytic activity (onset potential, E onset = 1.001 V; half-wave potential, E 1/2 = 0.945 V) as well as enhanced catalytic stability in practical zinc-air batteries (over 1500 h at 10 mA cm −2 ). The electronic bridge structure linking single atoms and clusters reported in this study unlocks new avenues for the rational design of next-generation TM-N-C catalysts. • In situ cluster-trimming enables direct single atom - cluster interaction. • Direct interaction decouples active site electronics, enhancing oxygen adsorption and activation. • DFT and in situ spectroscopy reveal boosted O O bond cleavage and 4e − ORR pathway. • The catalyst delivers over 1500 h of stability and high performance in practical Zn-air batteries.