Beyond Electronic Interaction: Ru Sub-Nanoparticles Reconfiguring Interfacial Water on Ru-Co Diatomic Sites for Accelerated Oxygen Reduction.

Synergy between metallic nanoparticles and single-atom sites offers considerable potential for developing advanced electrocatalysts. However, the synergistic mechanism in such complex architectures under operating conditions remains elusive. Herein, a two-step approach involving selective etching and co-confined adsorption was developed to precisely construct CoRu/RuNPs catalyst, featuring Ru-Co diatomic sites coupled with Ru sub-nanoparticles, which demonstrates excellent oxygen reduction reaction (ORR) performance with a half-wave potential of 0.91 V and a peak power density of 369 mW cm-2 in zinc-air batteries, along with outstanding cycling stability over 1350 h. Beyond modulating the electronic structure to weaken OH* adsorption on Ru-Co diatomic sites, the Ru sub-nanoparticles also induce an alternative thermodynamic pathway for enhanced ORR kinetics, in which interfacial water dissociate on oxyphilic Ru sub-nanoparticles and facilely supply protons to oxygen-containing intermediates on neighboring Ru-Co diatomic sites. This work not only advances the construction of synergistic active sites but also opens a new paradigm for designing advanced electrocatalysts by harnessing the interfacial environment beyond electronic structure modulation.